Originally Posted by
Pop N Wood
That is why car tires are specified by profile as well as width. 245x60 tires do have a larger diameter than 225x60 series tires. To keep the same height you need a lower profile.
Here is a good reference for the circumference (hence diameter) of bike tires by size.
https://www.cateye.com/data/resource...ENG_151106.pdf
A 700x25c tire has a diameter of 2105/3.14 mm while a 700x32c is 2155/3.14 mm
Just for funsies, a 245/60 and a 225/60 can have the same diameter. You left out the third variable in car tire measurements which is the wheel size. The 245 or 225 mentioned are the tire width. The 60 is the sidewall height expressed as a percentage of the tire width. a 245/60R16 is the same diameter as a 225/60R17.