Originally Posted by RanJerEDGE
a 235/75 15 tire is 28.9" in diameter
63360 in/mi / Pi*D = 697.85 rev/mile
and for the 31 = 650.58 rev/mile
and the speed doesn't matter
That's the theoretical revs/mile. The true revs/mile is usually different because actual computed circumference is not necessarily the same as rolling circumference. Also, most "31-inch" tires are actually a little smaller than the sidewall size designation might imply.
For the most accurate number, it is best to use the measured
data from the manufacturer's website. BFG site lists 30.7" diameter and 677 revs/mile for the 31x10.50R15 A/T KO used on the LII and 677 is exactly the number that my LII had in the PCM from the factory.