Would someone explain wheel sizes.
If I am not mistaken, the wheels on my Trek 520 touring bike are 700C. There are no markings, and of course, no documentation of any kind. I assume 700 means 700mm, so 700 / 25.4 = 27.56 inches.
If I measure the rim however, its diameter is approximately 25.1 inches.
If I buy Continental tires, the size is 28 inch, but I have to buy 27 inch Bontrager tubes.
To make matters worse, per this link, tires come in sizes of 26, 27, and 28 inch, and size 700.
How can I determine my wheel size, and are these various sizes interchangable. Also, is the 'C' suffix important, and what does it mean?
Of course the tires are marked, but I am under the impression (per the dealers comments) that Continental marks their tires differently than everyone else. Also, the tire markings don't help for ordering a new wheel.
With so many tire sizes available, how can I know if I am using the correct size.
After reading the various answers here, I should explain that my confusion on this matter stemmed from the fact that I used to work as an auto mechanic. In the auto industry, car tires are based on wheel size, 13", 14", 15" etc, and there is no possible way to mount a 15" tire on a 13" rim for example.
So when I saw all these different tire sizes, I assumed they all required a different wheel size, but in fact, there is essentially just one wheel diameter for my type of bike, which they refer to as 700C, which is actually 622mm.
I also initially assumed that the C referred to the wheel's width, but that isn't true either. The C is apparently just antiquated terminology.
So at least in theory, I can mount a 26", 27" 28" or 29" tire on my 700C (622mm) rim. I just need to verify the width of the tire is suitable my wheel width, which is what Sheldon Brown's article explains.
Also, I measured my Continental tires, which are marked as 28 inch. They actually measure 27 inches (fully inflated), which must be why my dealer calls their sizing non standard.