Kind of surprised that nobody has mentioned date codes yet. Tires in the states will have a date of manufacture code molded into the sidewall. It is an oval shaped stamp with four numbers, such as 4016. The first two digits are the week it was built, as in the 40th week of the year, or roughly the first week of October. The second two numbers are the year, or in this case 2016. The important part of this information is that tires actually get too old to be safe, regardless of their wear, or lack of it. This is a huge deal with any RV, since most are used infrequently enough to ever really wear the tires out. As a result, tons of large expensive motorhome tires end up being replaced, with very little wear, and often hit the scrap pile looking nearly new, since they are seven, or more years old. There is some debate on what is too old, but most tire and vehicle manufacturers have limits available online. The seven year mark is pretty common. Old tires are prone to failure and loss of control of the vehicle, largely since they have lost their flexibility and tend to crack and fail. This problem can be much more severe in extremely sunny, hot climates. I blew a tire in the southwest, and just wanted to find a pair of used replacements to get me back to the home in PA. While searching at a used tire dealer, I found many examples of dried, cracked tires that looked about 20 years old, according to my past experience, but were only a few years old, and had suffered from a lot of UV damage. Since the MMM mantra is to use a vehicle as little as possible, older, potentially dangerous tires are probably a more serious issue that the average consumer faces.