got a truck with 3.23 gear and 29x15.5x15 M/Ts

they measure 27 1/2" tall...(do not know why its called a 29" tire?)

at 2000rpm its at 55mph

if I go to a 3.91 gear,what is the rpm going to go up to at 55mph?

what size tire would work the best with a truck and 3.91s for the street

318/360 heads/stock intake-Q-jet
258/264-.485/.485 lift 60710 voodoo roller cam
904 lock up with a stock HS tc

guess I am just asking if that tire is too small for a 3.91 gear

thanks for helping

This is an awesome tool... put together by a Moparts member but I don't remember who...

RPM Calc

Darren

http://www.f-body.org/gears/
This too if you don't know the height of the tire, but know the size

3.91 you can almost double the tach reading and be fairly close. IE: 3500 = 70 MPH.