When do you really need new tires?

[Miss. Takes]

I just took my 2011 Camry in for maintenance which has 45k miles. I was told everything was good except they marked all my tires as red requiring urgent attention and said I needed 4 new tires and wanted to charge me about $800. Here are my questions:

1. When do I REALLY need to change my tires? The tires look completely fine to me, I know there is some wear on them, but I have certainly seen much worse on other cars getting along fine. What happens if I don't change my tires? I of course will change them if they are completely worn out, but they don't look that bad to me.

2. Is there a recommended time line on when I should be getting new tires? After a certain amount of years or miles?

3. How much should tires cost? Where is the best place to get them and have them installed?

4. Finally, I was told that my tires were rotated. What exactly does that mean? One of the tires has a missing hubcap and it is in the same spot, are they supposed to move front tires to back? Left to right? What does this service actually do and how do I know if it was actually done?

Sorry for such basic questions, I don't know anything about cars. Thanks very much for your expertise.

[geekette]

Here's a page on tread depth and recommendations on when to buy new.  If your wear bars are showing, they are about done.  Worn out tires might work just fine in dry weather, but cause you to lose control in rain. 

Cost of tires depends greatly on size, brand, and warranty.  The shop we use generally gives us a few to choose from.  My DH likes performance tires <sigh>.  I go for longevity.  And price.  I paid $500 for tires (with lifetime balance/rotate) for my HHR (slightly smaller than Camry tires, I believe), and they went on at right about 45k miles as well.

We have a shop we've trusted and used for decades, but warehouse stores might have good prices.  After one bad experience, I don't like the tire only stores.

Rotating is moving them front to back and/or side to side, depending on the tires.  The hubcaps have to come off to move the tires, so they probably just put them on where they were.  I hope they were balanced as well - you can sometimes see shiny new balance weights, but not when they're on the back side of the tire.  Routine balance/rotate keeps them from wearing prematurely, as will keeping them inflated to specs.

[Gone Fishing]

1.http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=51

2.As far as miles go-see #1.  If you drive very little you can age out a tire.  Although the little weather checks that show up are not a good indication.  Rule of thumb is that you might want to consider changing if they are over 10 years old.

3. You should be able to get a decent set of tires for a Camry for $400 or so total. I like to go for mid range tires in the 50-60,000 range.  If you can get 80%+ out of the wear rating you are doing pretty good. Mounting/disposal/balancing charges shouldn't be more than $50 of the $400 total.

4.Rotating is what it what it implies.  On a front wheel drive far with radial tires, that usually means swapping the tires front to back on the same side.  This helps even out wear on the tires and make them last longer.  The hubcap you mention was probably removed, set aside for the rotation, then reinstalled in the same position after the tires were rotated.  Generally I keep the tires with the most tread on the front, because they wear faster there, this does not mean you can run around with bald tires on the back, you risk losing control of the rear of the car if you try that. 

[Greg]

As the others have said there are wear indicators molded into the tread design.  Visit a tire store and ask them for their opinion, and ask them to show you on the tire why/why not.  If your tires are rotated regularly, the wear should be even front/back and all four may need replacing.

[PeachFuzzInVA]

Most of those Camry's came with 17" V-rated tires. $800 is not too incredibly bad if it includes the alignment and it's a good quality tire like a Bridgestone, Michelin, or Yokahama (all OEM tires on those vehicles). You can get El-Cheapo tires for it that won't last for less, but you'll just wind up spending more in the long run replacing the tires at a 2-1 rate versus putting a quality name brand tire on it. Toyota pushes a house brand called Nexen that you could do, but they won't last anywhere near as long. Also, Toyota does their tires buy 3, get the 4th for $1 probably 10 months out of the year, so if you're price shopping don't overlook them. I used to regularly have customers leave me thinking they could get a better price only to come back a few hours later when I was working as a service advisor at Toyota. Don't replace your tires until you hit 2/32" of tread. If you turn the steering wheel all the way one direction and look at the tread on the tires, you'll see bars in between the tread, those are called the wear bars and they're 2/32" tall. They are the manufacturer's way of indicating to you that its time to change the tires when the tire's tread is worn down even with them.

[Grateful Stache]

When it comes to car safety, don't be a mustachian: Be smart!

Seriously, tires are an incredibly important component to vehicle safety. At 45,000 miles, it is likely that they need replacement. Don't put you, your family, or others at risk.

Cheers.

[FrugalSpendthrift]

2. Is there a recommended time line on when I should be getting new tires? After a certain amount of years or miles?

There is no specific time line or mileage. It depends on how well they were taken care of, proper tire pressure, decent alignment, road conditions, weather.  Check tread depth, look for dry rot or other damage.  If you drive in conditions that are wet or snow, then more tread depth will give you more grip and be safer.

[Sid Hoffman]

Read the size off the side of the tire and post it to the forum.  At least then we know what you're working with.  There's a variety of trim levels for the Camry, but if yours has accessory wheels or some sort of appearance package that changed out the wheels for a different size, then that is the size you'll need to be looking for.  Hence, why I would rather know what size tires you currently have instead of what trim level the car is.

For example, the stock Camry LE with standard wheels is 215/60-16.  I'm seeing some mail-order tires as cheap as $250 in that size, but they pretty easily run up to and beyond $400 for the bigger brand names with longer treadlife warranties and better handling/noise qualities.  You'll likely not see pricing like that at a tire shop, since they usually quote prices as mounted & balanced, which is usually at least another $25/wheel.  So easily you're at $500 for just the tires, mounted and balanced.  It would also be good to at least get a front wheel alignment, and potentially a 4-wheel alignment if there's abnormal wear on the previous set.  That's another $80-120 or so.

Lastly, you may add road hazard insurance, which can be another $7-10 per tire, but is basically an insurance policy so if you get a flat tire that cannot be repaired with a standard patch/plug kit, they will replace 1 or 2 tires, as dictated by wear.  For example, if the tires are already half worn, they need to do 2 tires so they are even left to right.  If you live in an area where flats are common, that can be handy insurance to have.  Otherwise you can pass.  I always pass and only twice have I gotten an unrepairable flat in probably my last 200,000 miles of driving.  I'm pretty sure paying out of pocket for tire replacement has still put me ahead of where I'd have been with free tire replacement, but for how cheap the hazard insurance is, it might be handy.

So bottom line, if you're rolling the standard LE tire size, you can probably have it done at an independent shop perhaps as cheap as $500 for all 4, mounted & balanced with at least a front-end alignment.  I can easily see it being even more (especially from a dealer) for the brand-name tires and a 4-wheel alignment.  $800 isn't robbery, but you can almost certainly save by getting off-brand tires from an independent shop and doing only the front-end alignment.

[Joel]

When it comes to car safety, don't be a mustachian: Be smart!

Seriously, tires are an incredibly important component to vehicle safety. At 45,000 miles, it is likely that they need replacement. Don't put you, your family, or others at risk.

Cheers.

I second this.

[SweetTPi]

I agree on the safety first issue.  On the whole 'when' aspect, well, I have no idea- I didn't notice mine until I found myself slipping sideways while driving uphill in the rain.  So, I'd say about 1000-2000 miles before that point!  Your ability to stop is only as good as how well your tires can grip the road, which is compromised when they wear out.  It is even more dangerous in poor weather.

As for new tires, I don't know where you are, but if you have a good warehouse around it may be worth looking into.  On Costco's site, http://tires2.costco.com//, you can select your car, and they'll have what tire sizes you need, and give a quote online.  You can call around to various local shops and get quotes, too.  Ask for not only the tire cost, but the cost for installation.

I just bought Yokohama all-season tires for my Corolla (which has a different tire size, note) and it was $500 or so.  I did not have an alignment done (should I have?).

[Gone Fishing]

When it comes to car safety, don't be a mustachian: Be smart!

Seriously, tires are an incredibly important component to vehicle safety. At 45,000 miles, it is likely that they need replacement. Don't put you, your family, or others at risk.

Cheers.

I second this.

This is the exact reason why you need to educate yourself on cars, houses, insurance, etc.  It is the easiest sales pitch in the world to take an uneducated person, tell them they are in danger, then sell them some overpriced fix to make them "safe" again.  Or you could just take their advice, because, as we all know, car repair shops are all as honest as the day is long.  At minimum, always get a second opinion.  I'm sure you will be fie to drive a mile or two down the road to another shop.  I have a "second opinion" threshold of about $200 for anything I feel I don't understand.     

[CDP45]

Costco! I think tires are super critical, luckily the technology is great to keep the cars on the road and not slide like in the past...The stickier the tire, the less chance of skidding and the faster stopping.

[ShortInSeattle]

I have 4WD and the tire people told me that if I need to replace one (due to damage) I need to replace all four because 4WD "auto-magic-nonskid-computer-thingy" requires all four tires be the same circumference.

True, or bogus?

[PeachFuzzInVA]

I have 4WD and the tire people told me that if I need to replace one (due to damage) I need to replace all four because 4WD "auto-magic-nonskid-computer-thingy" requires all four tires be the same circumference.

True, or bogus?

AWD or 4WD? I've seen transfer cases destroyed in AWD vehicles with tread depth differences as little as 1/8". The last transfer case I replaced was $3000 in a Nissan Murano because of this very issue.

[PeachFuzzInVA]

It would also be good to at least get a front wheel alignment, and potentially a 4-wheel alignment if there's abnormal wear on the previous set.

Just to follow up on this, the Camry's, and most modern fwd vehicles, require adjustments at all 4 corners. Believe it or not, you can adjust the toe in the front of the vehicle and actually watch the settings in the rear change as you're adjusting the front. Be wary of your local tire shops and mom and pop type shops that just "set the toe and let her go," as there's more to doing an alignment than that. The shop I work at now, we actually load the vehicle with 150lbs worth of sandbags to simulate a driver in the vehicle to ensure that the alignment is as accurate as possible. Make sure you ask for the before/after printout when they do the alignment. Any reputable shop will offer it up.

[m8547]

I have 4WD and the tire people told me that if I need to replace one (due to damage) I need to replace all four because 4WD "auto-magic-nonskid-computer-thingy" requires all four tires be the same circumference.

True, or bogus?

It's probably a good idea to have matched tires (at least pairs) on any car. You may be able to get the new tire shaved down to match the old ones? I don't know if that's a thing, but it should be. I'm sure tire stores want to sell you four new ones instead, though.  If it has a full size spare you could include that in the rotation from the start (look up the pattern), and then if you damage one you still have four tires that are all the same. But really, I think destroying a tire is very rare. Plugs for little holes are common, but I think passenger car tires (good ones at least) are engineered to rarely blow out because the result is more catastrophic than on a big truck that has 17 other tires if one blows out (as long as it's not one of the front two).

By this same logic I turn down any extended warranties when buying tires. Last time the one they offered me cost 10-15% of the cost of the tire. I figure I have far less than a 10-15% chance of destroying a tire beyond repair over the life of them.

[Greg]

I have 4WD and the tire people told me that if I need to replace one (due to damage) I need to replace all four because 4WD "auto-magic-nonskid-computer-thingy" requires all four tires be the same circumference.

True, or bogus?

For cars like Subarus with full time AWD it's true. 

[Primm]

I have a corner that I go round in my car at a particular speed. If I slide round in a controlled fashion my tyres are fine. If the back end starts to slide out more than it should, I get new ones. :)

[guitar_stitch]

I have 4WD and the tire people told me that if I need to replace one (due to damage) I need to replace all four because 4WD "auto-magic-nonskid-computer-thingy" requires all four tires be the same circumference.

True, or bogus?

AWD or 4WD? I've seen transfer cases destroyed in AWD vehicles with tread depth differences as little as 1/8". The last transfer case I replaced was $3000 in a Nissan Murano because of this very issue.

I can verify this.  My AWD Honda Element is now FWD because I failed to rotate tires often enough.  Burned up the clutches in the rear diff.

[dragoncar]

If you do need tires, check out this slickdeal:

http://slickdeals.net/f/7238156-discount-tire-direct-coupon-motor-wheels-tires-100-off-400-or-more-w-stackable-rebates-free-shipping

[Sid Hoffman]

AWD or 4WD? I've seen transfer cases destroyed in AWD vehicles with tread depth differences as little as 1/8". The last transfer case I replaced was $3000 in a Nissan Murano because of this very issue.

True, and it came up recently on another messageboard recently:

AWD and 4WD vehicles.....a tale of caution regarding tire diameter and system damage

[DarinC]

Well, it can, but in that case it looks more like crumby design/maintenance.

http://forums.vwvortex.com/showthread.php?7037139-AWD-and-4WD-vehicles-a-tale-of-caution-regarding-tire-diameter-and-system-damage&p=86266662&viewfull=1#post86266662

[RWD]

I just took my 2011 Camry in for maintenance which has 45k miles. I was told everything was good except they marked all my tires as red requiring urgent attention and said I needed 4 new tires and wanted to charge me about $800. Here are my questions:

1. When do I REALLY need to change my tires? The tires look completely fine to me, I know there is some wear on them, but I have certainly seen much worse on other cars getting along fine. What happens if I don't change my tires? I of course will change them if they are completely worn out, but they don't look that bad to me.

2. Is there a recommended time line on when I should be getting new tires? After a certain amount of years or miles?

3. How much should tires cost? Where is the best place to get them and have them installed?

4. Finally, I was told that my tires were rotated. What exactly does that mean? One of the tires has a missing hubcap and it is in the same spot, are they supposed to move front tires to back? Left to right? What does this service actually do and how do I know if it was actually done?

Sorry for such basic questions, I don't know anything about cars. Thanks very much for your expertise.

Everything you could possibly need to know about tires:
http://www.carbibles.com/tyre_bible.html

1) You should replace tires when they are 6 years old (by date stamp) or have less than 3 mm of tread depth. From that link: "at 1.6mm, despite still being perfectly legal, the stopping distance is increased by 40% in the wet over tyres that have 3mm of tread left."

2) Don't worry about miles, just age and tread depth is fine (see #1 answer).

3) I usually research and buy my tires from Tire Rack. They will ship them directly to your preferred installer. Prices will vary based on the type of tire and size. I've found you can usually get good tires for normal cars for less than $100 each. The cheapest place to install tires may not be a dedicated tire shop. In my area my usual auto repair shop was cheaper than the tire shops. Call around for quotes. I'd expect less than $20/tire for all mounting/balancing/fees.

4) Rotating tires is taking the wheels/tires off and putting them back on a different hub of the car. It's done for wear balancing. Depending on your car and tires the rotation pattern will be different. Directional tires can only be swapped with the other tire on the same side. Staggered tires (wider in the back than front) can only be swapped across the same axle (not sure how useful that would be though). As mentioned you'll want to keep a closer eye on the relative wear if you have an AWD/4WD vehicle. Tire tread depth gauges are quite cheap and you'll be able to measure whether your front or back tires are wearing faster (it'll likely be your front tires wearing faster on a Camry) as well as which part of the tires (which can help detect alignment and inflation pressure problems).


Don't neglect your tires. I cheaped out years ago and didn't replace the rear tires of my wife's car since they still had some tread left, opting to only replace the fronts. She fish-tailed around a corner in the rain and totalled the car. Saving maybe a couple hundred bucks on tires cost me at least $1000 in the value of the car, the driving confidence of my wife, and who knows how much in insurance. It's particularly important that your rear tires are not significantly more worn than the fronts.

[Sid Hoffman]

Don't neglect your tires. I cheaped out years ago and didn't replace the rear tires of my wife's car since they still had some tread left, opting to only replace the fronts. She fish-tailed around a corner in the rain and totalled the car. Saving maybe a couple hundred bucks on tires cost me at least $1000 in the value of the car, the driving confidence of my wife, and who knows how much in insurance. It's particularly important that your rear tires are not significantly more worn than the fronts.

Side note: You are always supposed to have your good tires in the back.  Tire shops will do this by default if they even halfway know what they're doing.  Reason is that understeer is far safer than oversteer, as your wife learned the hard way.

Also side note, it's very true about aquaplane resistance dropping dramatically when you're down around the legal limits.  The 1.5mm listed is about 1.9/32".  In the US, they usually quote 2/32" as the legal minimum.  3mm would be about 3.8/32" of tread.  Most tires ship with around 11/32" of tread depth.  In parts of the Southwest where you may only get 10-20 days of rain, and especially if you're a work from home or retired person you can probably get away with driving down to the legal limits since you have the ability to simply choose not to drive when it rains.  For normal people, yeah, replacing the tires well before they hit the wear bars (legal limit) is a good idea.

If you pick up calipers with a feeler gauge at the end, you can measure the tread depth yourself pretty quickly and accurately.  That would be in line with the do it yourself nature of a mustachean, although digital calipers are easily a $50 tool if you're buying a nice, brand name one.  I see cheap mechanical ones on Ebay like this one for $17.  Being mechanical, it may not be quite as accurate as the digital ones, but still more than good enough for tire depth.  Plus since it's mechanical, you won't be replacing the batteries all the time like I've done for my digital calipers over the years.  Even though I rarely use it, the stupid batteries run down on their own after a few years even packed in the foam case outside the instrument. 

[RWD]

If you pick up calipers with a feeler gauge at the end, you can measure the tread depth yourself pretty quickly and accurately.  That would be in line with the do it yourself nature of a mustachean, although digital calipers are easily a $50 tool if you're buying a nice, brand name one.  I see cheap mechanical ones on Ebay like this one for $17.  Being mechanical, it may not be quite as accurate as the digital ones, but still more than good enough for tire depth.  Plus since it's mechanical, you won't be replacing the batteries all the time like I've done for my digital calipers over the years.  Even though I rarely use it, the stupid batteries run down on their own after a few years even packed in the foam case outside the instrument.

I have a very basic tire tread depth gauge, something like this (you can probably find a similar one even cheaper in an auto parts shop):
http://amzn.com/B0002STSQM

[Rural]

I have a bunch of basic tread depth gauges:


http://betthearm.com/wp-content/uploads/2012/03/Penny-2007.jpg

[GardenFun]

I have a bunch of basic tread depth gauges:


http://betthearm.com/wp-content/uploads/2012/03/Penny-2007.jpg

Good one!  Was going to post the same item. 

Uncle always said to put the top section of the penny in the tread and "if you can see Lincoln's head, you don't have enough tread".  Crazy how that stuck with me.

[Sid Hoffman]

I have a very basic tire tread depth gauge, something like this (you can probably find a similar one even cheaper in an auto parts shop):
http://amzn.com/B0002STSQM

That certainly is cheaper, although with calipers, you'll find yourself using them to measure all sorts of stuff, mainly round things or objects you can't easily get a ruler in to with enough precision to know what you need to buy for replacement parts.  If you are only interested in tire tread depth, I guess the specialized tool is the cheapest way to go.  With calipers, you can use it for other DIY stuff too, assuming you do enough DIY stuff to ever need calipers.  :)

[Runge]

I have a bunch of basic tread depth gauges:


http://betthearm.com/wp-content/uploads/2012/03/Penny-2007.jpg

Good one!  Was going to post the same item. 

Uncle always said to put the top section of the penny in the tread and "if you can see Lincoln's head, you don't have enough tread".  Crazy how that stuck with me.

I use a quarter to tell me when it's time to start really keeping an eye on things and setting aside money for new tires, after that I'll use the penny trick to tell me when to pull the trigger as well as paying more attention and care while driving.

[frugal_engineer]

When it comes to car safety, don't be a mustachian: Be smart!

Seriously, tires are an incredibly important component to vehicle safety. At 45,000 miles, it is likely that they need replacement. Don't put you, your family, or others at risk.

Cheers.

I second this.

This is the exact reason why you need to educate yourself on cars, houses, insurance, etc.  It is the easiest sales pitch in the world to take an uneducated person, tell them they are in danger, then sell them some overpriced fix to make them "safe" again.  Or you could just take their advice, because, as we all know, car repair shops are all as honest as the day is long.  At minimum, always get a second opinion.  I'm sure you will be fie to drive a mile or two down the road to another shop.  I have a "second opinion" threshold of about $200 for anything I feel I don't understand.   

Best advice on this thread.  If you aren't educated on a topic with safety implications, its SO easy for someone to convince you that unless you buy something from them you're being "unsafe".

Tires can absolutely be dangerous if they're in bad shape, but you need to educate yourself enough so you can smell BS when its wafting your way.

[Grateful Stache]

I can verify this.  My AWD Honda Element is now FWD because I failed to rotate tires often enough.  Burned up the clutches in the rear diff.

Damn... I have a CR-V, so I'm curious... Can it be fixed?

[BlueMR2]

I can verify this.  My AWD Honda Element is now FWD because I failed to rotate tires often enough.  Burned up the clutches in the rear diff.

Damn... I have a CR-V, so I'm curious... Can it be fixed?

I'm sure it can.  I know Subaru and DSM owners that have had the same problem.  In those cases it's normally a $1500 transfer case replacement.  If it happens to be a rear diff that bites it (like from driving too many high speed miles on a spare tire), that's just $1000.

[TrulyStashin]

Don't neglect your tires. I cheaped out years ago and didn't replace the rear tires of my wife's car since they still had some tread left, opting to only replace the fronts. She fish-tailed around a corner in the rain and totalled the car. Saving maybe a couple hundred bucks on tires cost me at least $1000 in the value of the car, the driving confidence of my wife, and who knows how much in insurance. It's particularly important that your rear tires are not significantly more worn than the fronts.

+ 1,000

In August of 1985, two weeks before our senior year of high school, my cousin Paul was driving home from church in the rain.  He braked and because the tires were bald, he lost control and crossed the center line of the road. 

He died in the resulting head-on accident. He was 17.

Not replacing tires and not doing tire maintenance is a perfect example of cheap, not frugal.  Don't be a sucker for performance tires, but spend the money on a set of good ones and then keep them properly inflated and rotated.

[m8547]

+ 1,000

In August of 1985, two weeks before our senior year of high school, my cousin Paul was driving home from church in the rain.  He braked and because the tires were bald, he lost control and crossed the center line of the road. 

He died in the resulting head-on accident. He was 17.

Not replacing tires and not doing tire maintenance is a perfect example of cheap, not frugal.  Don't be a sucker for performance tires, but spend the money on a set of good ones and then keep them properly inflated and rotated.

A lot of things have gotten better since 1985:
-Cars are built to keep the occupants safer, and they have better airbags, etc.
-ABS in many cars helps prevent major loss of control (It became common in the late 2000s and became mandatory in 2011)
-Newer cars with stability control actively try to keep the car moving in the direction the driver intends. They can't prevent all skidding and can't make up for bald tires, but they do a good job of reducing the impact. IIRC, stability control decreases single-car accidents by 25%. Stability control was phased in in the past few years and became mandatory on 2012 and newer vehicles, and it's been mandatory on SUVs for a while. If you live in a snowy climate, I highly recommend it, even though it can get in the way of normal winter driving sometimes.

Even with all that technology, you still need safe tires, though. Electronic aids can only mitigate the problem, and I hope no one would ever rely on their airbags as a substitute for keeping the vehicle in safe condition.

[eyePod]

When it comes to car safety, don't be a mustachian: Be smart!

Seriously, tires are an incredibly important component to vehicle safety. At 45,000 miles, it is likely that they need replacement. Don't put you, your family, or others at risk.

Cheers.

^^^owns stock in Michelin...

[more4less]

You don't really need tire depth gauge - just use tire wear indicator.

Until it's on the same level as the rest of the thread you're safe. Worn tires don't really affect grip on the dry or wet road (I'm pretty sure cousin Paul's accident would have same outcome with new tires). However, bald tires really increase risk of aquaplaning (esp. on higher speeds) - the channels on tire's thread are designed to let water escape from the zone of contact with the road. When tire is too bald (or you're going to fast) through a puddle water doesn't have enough time to escape you end up going on the surface of water instead of asphalt. Especially dangerous on highway speeds.

So my advice to you - check tire wear indicators on all tires. Also note the wear, it should be even on every tire. If tire worn in the middle, probably your tire pressure is too high. If tire worn on ends - pressure is too low. If tire is worn on inner or outer side then you need to check your alignment. If front are worn much more than rear - you forgot to rotate tires (do it every 10k miles, or better 5k).
If rain season is coming, change tires.
You don't have to buy top brands (Michelin, Yoko or Bridgestone) - there are bunch of really good brands (Falken, Toyo, Kumho) which offer much better value without any compromises in quality. Used tires aren't worth it, unless you're trying to sell car and it has bald tires.

[RWD]

You don't really need tire depth gauge - just use tire wear indicator.

Until it's on the same level as the rest of the thread you're safe. Worn tires don't really affect grip on the dry or wet road (I'm pretty sure cousin Paul's accident would have same outcome with new tires). However, bald tires really increase risk of aquaplaning (esp. on higher speeds) - the channels on tire's thread are designed to let water escape from the zone of contact with the road.

Even down to the wear indicator is less safe than 3 mm. I already posted this in this thread, but it seems it merits reposting:
"at 1.6mm, despite still being perfectly legal, the stopping distance is increased by 40% in the wet over tyres that have 3mm of tread left."
http://www.carbibles.com/tyre_bible.html

That is not anecdotal or guesswork, they went out and tested it. 40% increased stopping distance in the wet is not something to scoff at.

Good news is that the recommended 3 mm is approximately double the wear indicator, which still makes it fairly easy to use to eyeball if you need new tires (based on tread depth).

EDIT: This is also supported by TireRack:
"However in spite of the legal minimums, Tire Rack recommends that drivers expecting to experience wet conditions consider replacing their tires when they reach 4/32" of remaining tread depth. Tire Rack's tests have shown how shallow treads reduce wet braking traction and increase stopping distances"
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=163

[more4less]

Interesting. I don't really understand what causes this difference though.

[RWD]

The total volume of the channels/grooves is larger with more tread depth, hence it can handle more water while still keeping the tread in contact with the road.

[BlueMR2]

Interesting. I don't really understand what causes this difference though.

It all depends on how much water.  Full tread depth is even better than 4/32 if the water is deeper.  If the surface is just damp, no standing water, slicks will outperform any grooved tire.  However, if there's any standing water, the depth of the grooves becomes VERY important.

I had a set of tires that still had over 3/32 on them, but I went hydroplaning.  Expressway was just damp, UNTIL we got to a section with a blocked drain...  All of a sudden there was considerable standing water.  I hit it and skated across, ending up in a different lane from the one I started in, but still pointing the right way and didn't hit anything.  Another guy wasn't so lucky.  He hit the water, panicked, tried to correct, and spun out ultimately ending up in the ditch.

[more4less]

I'm not talking about aquaplaning, but the difference in braking distance.

PS: Also, why slicks outperform threaded tires? I know they do, but why? Friction depends on pressure and area of contact. But area cancels itself in formula (twice more area means half less pressure). Any physics majors around here? :)

[MattC]

So yeah, there are a few variables here for deciding when to replace tires:
1.  How likely are you to encounter a hydroplaning condition.  The less rain you encounter or if you know your route and it never accumulates water would lead me to run down the tread further.
2.  How likely are you to encounter snow.  Obviously deeper tread is better in the snow.
3.  ESC, ABS and rollover risk.  ESC and abs as well as a vehicle less likely to roll will make your vehicle better able to handle tire slippage.

And in any case, you're supposed to put your tires with the deeper tread on the BACK.  If a vehicle hydroplanes in the back but not the front, that's really bad since if you brake, the back can swing around, and you can roll. 

All of that said, for the no esc and no abs compact car driving in the northeast I do, I'll run my tires a little below the wear bars in the summer, but replace them a little before the wear bars in the winter, or get snow tires on.  If I drove a '90's Ford Bronco, I'd replace tires early at 4/32.  If I drove a new compact car (esc, abs), I'd let them go almost bald probably.  Regarding the Tire Rack wet stopping data, if a 40% increase in stopping distance would cause you to get in an accident, you're driving too aggressively, whatever tires you're using.

[RWD]

PS: Also, why slicks outperform threaded tires? I know they do, but why? Friction depends on pressure and area of contact. But area cancels itself in formula (twice more area means half less pressure). Any physics majors around here? :)

I imagine it's because the contact between tires and roads are not a perfect physics equation. More area is probably more stable to changes in road surface and more likely to find grip. In addition, you have to consider suspension geometry. When your suspension is compressed the camber of your tires changes. This is also why wider tires outhandle skinny tires.

Regarding the Tire Rack wet stopping data, if a 40% increase in stopping distance would cause you to get in an accident, you're driving too aggressively, whatever tires you're using.

Perhaps, but it is easy to imagine scenarios where improved braking performance could be the difference in avoiding an accident even if you were not driving aggresively. A vehicle running a red light in front of you or an animal jumping out from the side of the road come to mind. If you were driving on a closed circuit then driving conservatively would be sufficient, but there are too many variables in the real world.

The more Mustachian ones among us should be replacing tires based on age instead of tread depth anyway because they aren't driving much. I drive less than 3,000 miles a year on my daily commute, so my tires should have only about 18,000 miles or so on them when I need to replace them based on age (6-year shelf life).

[BlueMR2]

So yeah, there are a few variables here for deciding when to replace tires:
3.  ESC, ABS and rollover risk.  ESC and abs as well as a vehicle less likely to roll will make your vehicle better able to handle tire slippage.

Rollover risk would be my #1.  If you're driving an Explorer, CR-V, or any other high, tippy vehicle, it's critical to not ever lose a tire.  You basically have to treat your car tires the way motorcycle riders treat their tires (any failure can be disasterous).  For sports cars, there's not much concern as the probability of rolling is really low.  In one particular race I went over a bump, departed the ground while the car was rotating, and landed traveling sideways without rolling.  In comparison SUVs/crossovers can easily rollover in the simplest of skids.

[FarmerPete]

I have a Honda Element that blew a tire last spring.  Discount Tire gave me the AWD requires wheels to be withing 1-2/32 speech.  I was shocked to see research that it's true.  I did see that Tirerack will shave a tire down for you.  Unfortunately I didn't learn about that until after I had 4 brand new tires.  It might suck to buy a new tire and immediately wear it down to 50% tread, but if it's that or 4 new tires, it's probably a good deal, unless they give you a real good trade-in on your used tires.

I've got a tire tread depth gauge that I use.  It was dirt cheap.  I've used pennies in the past, and that works good enough for most people.  Since I rotate my own tires, I like to check wear side to side and a penny doesn't do it for me accurately enough.

[ender]

When it comes to car safety, don't be a mustachian: Be smart!

Seriously, tires are an incredibly important component to vehicle safety. At 45,000 miles, it is likely that they need replacement. Don't put you, your family, or others at risk.

Cheers.

I am very mustachian when I purchase new tires.

I buy them from Sam's Club, for a considerable amount off what they would cost elsewhere.

[PeachFuzzInVA]

You don't really need tire depth gauge - just use tire wear indicator.

Until it's on the same level as the rest of the thread you're safe. Worn tires don't really affect grip on the dry or wet road (I'm pretty sure cousin Paul's accident would have same outcome with new tires). However, bald tires really increase risk of aquaplaning (esp. on higher speeds) - the channels on tire's thread are designed to let water escape from the zone of contact with the road. When tire is too bald (or you're going to fast) through a puddle water doesn't have enough time to escape you end up going on the surface of water instead of asphalt. Especially dangerous on highway speeds.

So my advice to you - check tire wear indicators on all tires. Also note the wear, it should be even on every tire. If tire worn in the middle, probably your tire pressure is too high. If tire worn on ends - pressure is too low. If tire is worn on inner or outer side then you need to check your alignment. If front are worn much more than rear - you forgot to rotate tires (do it every 10k miles, or better 5k).
If rain season is coming, change tires.
You don't have to buy top brands (Michelin, Yoko or Bridgestone) - there are bunch of really good brands (Falken, Toyo, Kumho) which offer much better value without any compromises in quality. Used tires aren't worth it, unless you're trying to sell car and it has bald tires.

It looks like the inaccuracy of the worn tires not having any effect on grip on wet roads has already been corrected, but please don't ever try to tell anybody there's any similarities between a Falken/Kuhmo quality tire and your top brands such as Michelin and Bridgestone because it's simply not true. To put things in perspective, while in college, I worked for Tire America. They put out a company-wide memo that we were no longer to sell or install Falken/Sumitomo/Kuhmo on any luxury brands. Why did they do this? Simple, the quality of the tires weren't meeting the expectations of the customers. They did not ride, handle, or wear like the better brands. Over time, most of our sales staff stopped selling them on anything for these same reasons. I would recommend them on very small compact cars as they tend to be quite a bit easier on tires than your larger cars, but under no circumstances would I put any of those brands on anything bigger than an Ford Focus. By that point, you're just going to wind up replacing them when the other tire would have only been halfway through its life, ultimately costing you more money in the long run anyway.

As far as the slicks/traction thing, it's very simple also...more surface area = more friction = better traction.

[Mr.Foostie]

Too much paranoia and not one reference to buying used sets of tires.  Silly people trade their cars all the time and in snow belt areas especially, people often have two full sets of tires and rims.  Look on Kijiji or Craigs List, search for the tire size and vehicle and you may find tires on rims that are a direct fit requiring no remounting.  I purchased one nearly new set of Michelin all-seasons on rims for $80, total steal and best deal ever.  In the summer I bought a full set of very good Michelin X-ice winters on rims for $200.  I have bought a couple of sets of nearly new Bridgestone Blizaks and Goodyear Nordics mounted on rims all in the $200-$400 range.  By the time one was to buy tires, rims, mount them and pay the taxes, those deals are all in the 10%-50% range of what new tires cost.  There is no safety difference there, they were all good safe tires.  I also don't wear them out very fast, I run dedicated summers and dedicated winters so the wear is split, there is little to be saved by compromising and using all-season tires in the cold and snow if that applies.  That's my bit of safety paranoia, run the right type of tires for the season, the difference is huge.

For summer and all-season tires there is a lot of advertising hype, look at customer reviews on the web etc.  The hyper inflated prices of the well advertised "super safe" super expensive tires  are not worth it.  I have had better experience with cheaper Korean made tires, e.g. Hankook and Falken.  The uber expensive super safe tires with high mileage ratings have hard rubber compounds and my experience is that they suck in the rain, spinning very easily etc.  I have never really found Costco to be very competitive on this front in modern history, they sell the uber expensive brands at a slight discount, not a good overall value proposition in my opinion.

There are always a millions opinions about tires, mustachian bottom line, look for very good used ones before looking at new and don't get sucked into the safety advertising hype...

[RWD]

Too much paranoia and not one reference to buying used sets of tires.  Silly people trade their cars all the time and in snow belt areas especially, people often have two full sets of tires and rims.  Look on Kijiji or Craigs List, search for the tire size and vehicle and you may find tires on rims that are a direct fit requiring no remounting.  I purchased one nearly new set of Michelin all-seasons on rims for $80, total steal and best deal ever.  In the summer I bought a full set of very good Michelin X-ice winters on rims for $200.  I have bought a couple of sets of nearly new Bridgestone Blizaks and Goodyear Nordics mounted on rims all in the $200-$400 range.  By the time one was to buy tires, rims, mount them and pay the taxes, those deals are all in the 10%-50% range of what new tires cost.  There is no safety difference there, they were all good safe tires.  I also don't wear them out very fast, I run dedicated summers and dedicated winters so the wear is split, there is little to be saved by compromising and using all-season tires in the cold and snow if that applies.  That's my bit of safety paranoia, run the right type of tires for the season, the difference is huge.

We already had a thread recently on used tires... Whether you buy used or new tires is only tangentially related to when you need to replace your tires.
http://forum.mrmoneymustache.com/ask-a-mustachian/used-tires-20473/

For summer and all-season tires there is a lot of advertising hype, look at customer reviews on the web etc.  The hyper inflated prices of the well advertised "super safe" super expensive tires  are not worth it.  I have had better experience with cheaper Korean made tires, e.g. Hankook and Falken.  The uber expensive super safe tires with high mileage ratings have hard rubber compounds and my experience is that they suck in the rain, spinning very easily etc.  I have never really found Costco to be very competitive on this front in modern history, they sell the uber expensive brands at a slight discount, not a good overall value proposition in my opinion.

I think you're confused if you think the higher mileage rated tires are advertised as "super safe". Performance is typically inversely related to tire life.

There are always a millions opinions about tires, mustachian bottom line, look for very good used ones before looking at new and don't get sucked into the safety advertising hype...

I've tried to limit my posts on tires to facts and not opinions. For example, less tread means decreased performance in the wet. This has been tested and proven by multiple sources.

[gimp]

Some of you put way too much thought into how to save a few dollars on safety-crucial equipment. Buying nearly brand new tires on wheels for $80 is an exception, and even then, you better know how to do more than just look at the tread to decide how decent the tires are.

I'm a simple man. Grand touring, all-season, H or V are fine, though if V is an extra $4 I'll take those. Around 4-500 for a set plus installation. I routinely drive over a thousand miles a day through all sorts of weather; I like to drive fast, and around corners, too. I would not trust that to a used set of tires to save a few bucks.

I also find that saving 50% on tires means you're replacing them more than twice as often... and you're spending money on the mounting, too. Unless you mount your own tires, and who does that? Even most tree-shade mechanics I know, who have no problem with wheels, won't mount the actual tires on the wheels.