Lew,
The taller the tire the more it will effectively raise your gear ratio. Example per Isky Ratio Computer;; 25" tall tires with 3:10 gears would let your crusie at 60MPH at 2400RPM. 28" tall tires would lower that to just over 2100RPM. I run 235/60 which when mounted are 25" tall with 3:27 gears and in 5th gear I can cruise at 70 at 1900RPM. Should have gone to a .8 split in the transmission incstead of the .6.
Edit:: The above calculations are based on a straight 1 to 1 drive ration, not the overdrive 5th gear. My 60 MPH speed with the 3:27s is at 2900RPM. I have ran the car through the CHP
radar testing setup at several speeds ranging from 50 to 90 and all have been right on the mark to the exat RPM and MPH when we did the math.
Ron
