Bicycle tire codes
 

I need to replace the tires on my bike.
The code on the tires reads 700x38C
The problem is that I am finding tires with only 700x38 - no C at the end.
And in most models of tires (such as on sites like Nashbar) 700x38 's are hard to find. 700x32, 700x36 are more common.
Must I stick with exactly 700x38C?
Thanks

No, as long as the tires are 700 x something, they will fit on your wheel. You probably want to stay fairly close to 38, so 700x32 or 700x36 would work just fine.

700 is the nominal circumference of the wheel. Originally there were 700a and 700b sizes as well as 700c, but these have long been obsolete. All modern 700 wheels are 700c. The other number is the width of the tire, as long as its close, there will be no problems.

As usual, there's an excellent Sheldon Brown article that explains the details: http://sheldonbrown.com/tire-sizing.html

The "700x38C" is actually a bit of a misnomer as the "C" in 700C refers to the rim diameter but it's all the same thing. Bicycle rims are pretty tolerant of variations in tire width (the "38" means a 38 mm wide tire) so anything in the 32 to 38 range will work fine.

Read the Sheldon Brown article mr_antares referenced. It's an excellent primer on the confusing and odd-ball nomenclature of bike wheels and tires and the system (ETRTO/ISO) developed to make some sense of it.

As said above, most likely anything that says "700 X xx" should fit, unless you have a weird old french bike or a GT Hybrid from the mid '90s.
There are different 700s - 700A, B, and D, however, these are extremely rare.

The only thing you should avoid is picking tires narrower than your rim, so 32, 35, 36, 38 will be 100% fine.

Incidentally, in my experience, 700 X 38 is a pretty common size for hybrid or trekking tires - but I have seen very few 700 X 36 tires in my life. Is there a particular make or model of tire you are looking for?

I'm searching for a cheap set of tires (Nashbar for example has 2 for $20) that are good for wet weather.
My bike is a road bike.