Originally Posted by ANR62NV
With these two tires sizes ^^ the difference on his speedo would be -2.3% ..... Or "slower" than actual speed of vehicle .... Or 1.38 mph @60mph
If the OP doesn't want much change he'd have to go with a 265-35-18 which would give a difference of -0.1%
Not significant .....
Actually a smaller diameter reads faster, not slower.
There is also a pretty distinct gearing advantage with a <25" diameter on the 5spd.