Originally Posted by
tarwheel
Width depends on the rims, which accounts for much of the variation.
Yes, but if you always use the same rims, you've eliminated that variable. For example, I have a 700x37 Conti that measures 34mm wide, and a 700x32 Vittoria that's 33.5mm. Both were mounted on the same rim, and inflated to their respective max psi. That discrepancy is not due to the rim(s), but the fact that one company's tire is undersized.