Michelin uses tire sizes that are unique to Michelin. The 265/75/22.5 tire made by other tire compaines is almost identical in overall diameter, 38.2" vs. 38.5," and approximately .2" diameter wider. Rev per mile for the 255/80/22.5 is 541, for the 265/75/22.5 - 537 rpm. No speedometer/odometer change or adjustment required.
(These specs are from a Goodyear site but very close to Bridgestone and Continental/General.)
'07 Winnebago Journey 34H, ISB-02, MH2500
Toad - '08 Ford Taurus X
Blue Ox, Aventa
US Gear UBS