Need hybrid tires for my "mountain" bike

[Mother Fussbudget]

Back-in-the-day I could work on my bicycles myself.  Today... I'm not so sure.
I won *woot!* a free 17" Marin ING Direct branded mountain bike in a raffle.  It has 21 speeds, great shifters, etc.
But the tires HUGE, VERY THIN walled, and have a skinny high-tech adapter that never seems to hold air.  I want to swap the tires out for something more hybrid-like (and add a polo/banana seat to make it a little more like my old 1970-ish Sears Screamer). 

Any ideas / links to actual tires/tubes I could buy and install myself - greatly appreciated.

The rims say:  "Double wall 622x18  6061-T6"
The tires say:  "Alex", "29x52 / 52" and "40  622  700x38C"

[NoraLenderbee]

Back-in-the-day I could work on my bicycles myself.  Today... I'm not so sure.
I won *woot!* a free 17" Marin ING Direct branded mountain bike in a raffle.  It has 21 speeds, great shifters, etc.
But the tires HUGE, VERY THIN walled, and have a skinny high-tech adapter that never seems to hold air.  I want to swap the tires out for something more hybrid-like (and add a polo/banana seat to make it a little more like my old 1970-ish Sears Screamer). 

Any ideas / links to actual tires/tubes I could buy and install myself - greatly appreciated.

The rims say:  "Double wall 622x18  6061-T6"
The tires say:  "Alex", "29x52 / 52" and "40  622  700x38C"

You can use 700x38C or 35C tires. Here's a thread about it:
http://forum.mrmoneymustache.com/ask-a-mustachian/i-need-road-tires-for-my-29-er-mountain-bike/msg275744/#msg275744

The valve is part of the inner tube, not the tire. Does it look like this one?
http://commons.wikimedia.org/wiki/File:Presta_valve_close.jpg

That is a Presta valve. The other kind is the Shrader valve, which is the same as the kind on car tires. You can't just replace a Presta tube with a Shrader tube because the Shrader valve is bigger, and it won't fit through the valve hole on the rim. You would need to drill out the valve hole. Or you could practice using the tubes you have until you get the hang of it. Presta valves hold air better than the other kind. But there is a technique to it.

[Mother Fussbudget]

Yes, I have Presta valves, and the Presta valve adapter for my pump. 
BUT... I hate dealing with those things - I'm going to drill, and move to the classic SV's. 

And thanks for the link to the earlier thread - that answered my question(s).

[GuitarStv]

If you have 18 mm rims a tire between 28 and 37 mm should work fine.  FWIW, I find that 32 mm tires are a great compromise for road usage.

If you're looking for particular brands that are decent:

Panaracer Pasela TG (http://www.amazon.com/Panaracer-Pasela-Tire-Wire-Bead/dp/B001CN5IRO/ref=sr_1_11?s=cycling&ie=UTF8&qid=1409184573&sr=1-11&keywords=panaracer+pasela+tg)
Shwalbe Marathon Plus (http://www.amazon.com/SCHWALBE-Marathon-Plus-Smart-Guard/dp/B00FM3LYC8/ref=sr_1_11?s=cycling&ie=UTF8&qid=1409184646&sr=1-11&keywords=schwalbe+marathon+plus)
Continental Touring Plus (http://www.amazon.com/Continental-Touring-Reflex-Bicycle-700x32/dp/B002SQZZDG/ref=sr_1_1?s=sporting-goods&ie=UTF8&qid=1409184689&sr=1-1&keywords=continental+touring+plus - Note, continental tires are actually sized a little smaller . . . so a 32 mm is about a 30 mm in reality, you might want to go one size up)

These tires are pretty tough/flat and puncture resistant, available in 32 mm, and roll well.  As far as tubes, just get tubes that match the tires you're buying (32mm tubes for 32mm tires) and make sure that if you have really deep rims you get a tall valve so that it'll fit through the rim.