RPMs of the engine will not be directly affected by the tires as such but the speed/milage will.
Indeed... but the speedo has been BROKEN since I bought my Pathy.. but the bigger the tire.. the less revolutions..hence the at 3,000rpm in 5th (before I fixed studs n added headers n all) I was doing 65mph with the 235/75/15 tires... then I was very close at 2,900rpm @ 65 with the 29's.. now.... who knows! I THINK I am doing ABOUT 65 @ 2,800rpm with the 31's....
These are the days I wish we had ONE STOCK VEHICLE to test with... :sniff: