# What is the difference between a road bicycle tire size 700 x 23c and I 700 x 23 [duplicate]

I've been riding road bikes for years but really wasn't too aware that there appear to be two different tire sizes, for example a 23C and a 23. ( 700 x 23. And 700 x 23c )

• Presumably thats 23c in the title - a 203c tire would be gigantic. Commented Jul 14, 2015 at 2:36
• sheldonbrown.com/tire-sizing.html Commented Jul 14, 2015 at 3:07
• Use the ISO 5775 sizes (23-622 in your case) whenever possible. It makes every size unique and denotes the important dimensions, not some theoretical outer diameter or some such. Commented Jul 14, 2015 at 6:07

700x23 and 700x23C and 700C x 23 and 700x23c and 700x23c all mean the same size of tire.

• And they are the same as ISO 23/622. Commented Jul 14, 2015 at 2:49
• (And also the same rim diameter as "29-inch" tires.) Commented Jul 14, 2015 at 2:50
• Back in the dark ages the idea was that 700 (mm) was the outside diameter of the wheel with the tire mounted. The 23 (also mm) was the size of the tire (more or less the diameter of cross section). And the 'C' was the size of the rim. There used to be 'A', 'B', and 'C' rims (and maybe also a 'no letter' rim). Roughly speaking A rims went with skinny tires, B with medium tires, and C with "fat" tires. Apparently the fat tires won. The idea was to keep the OD of the wheels similar, the problem was the rim diameter changed and it was a pain adjusting brake shoes if you changed wheel size.
– dlu
Commented Jul 14, 2015 at 3:02

They are indeed the same size of tire. For some reason, the "c" gets shuffled about, sometimes being put after the 700, sometimes being put after the tire width (in this case, 23mm), etc.

Peruse Sheldon Brown's Tire Cribsheet, and if you want lots of fun facts about tire sizing (including the difference between French standards and ISO standards), read Sheldon's article on Tire Sizing.

• Take a look at the way I edited your code (click on the edit link) to see how to code URLs so that you have a more meaningful link.
– dlu
Commented Jul 15, 2015 at 1:53
• No problem at all! Just thought you might be interested. If you just put in a URL Stack Exchange just "does the right thing" but if you want to you can also fancy them up without too much trouble.
– dlu
Commented Jul 18, 2015 at 13:25