The 265/75R22.5 is almost identical in revolutions per mile, 541 for the 255 and 537 for the 265. I replaced mine with Bridgestone R250's, 265/75 R22.5 last spring, have about 10,000 miles on them and did not notice any change in handling or ride. The speedometer error, if any, is negligible.
2007 Winnebago Journey 34H
Toad, '08 Ford Taurus X
Blue OX, Aventa
US Gear UBS