I hope this is the rightr place to post this question.

For anyone with an LLY/Allison running 265"s; How many rpm's @ 65 mph? and @ 70 mph?

And the formula is:

RPM = mph(OD ratio x rear gear ratio) x 336 / tire height

OR

RPM = 70 (.71 x 3.73) x 336 / 31.8
= 70 (2.6483) x 336 /31.8
= 62288.016 / 31.8
RPM = 1958.743

RPM = 65 (.7 x 3.73) x 336 /31.8
= 65 (2.6483) x 336 /31.8
= 57838.872 / 31.8
RPM = 1818.83

this should be purty close assuming OD ratio is .71, rear gear ratio is 3.73, and tire height is 31.8.
JP