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**truckster** · 11-03-2005, 04:10 PM

Here's the theoretical:

Tire size 265/75R16 should rotate roughly 650 times in 1 mile.

650 X 3.73 (diff. ratio) X .70 (final drive for 700R4) = 1683.5

At 60 MPH you should be travelling 1 mile in 1 minute, so your RPMs should be 1683.5.

Two possibilities: have you compensated your speedo gearing for oversize tires and for the drive ratios, and is your torque convertor locking?

11-03-2005, 04:10 PM	#6
truckster Senior Member Join Date: Jan 2001 Location: Orem, Utah Posts: 7,829	Re: My motor RPMs don't seem right Here's the theoretical: Tire size 265/75R16 should rotate roughly 650 times in 1 mile. 650 X 3.73 (diff. ratio) X .70 (final drive for 700R4) = 1683.5 At 60 MPH you should be travelling 1 mile in 1 minute, so your RPMs should be 1683.5. Two possibilities: have you compensated your speedo gearing for oversize tires and for the drive ratios, and is your torque convertor locking? __________________ I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson