[Zedn]

Leroy, I beleive the tyre width (ie 315) relates to the tyre being on a particular size rim not on its own. I would expect if you put both those 315 tyres on a 10" rim they would be the same width as the bead will blow out to seal on the rim. I have the sumitomo on an 11" rim and they measure about 313mm. The shape of the wall will make a difference from that angle as the actual tread width may vary, but the width of the tyre is the width for guard clearance.