Engine/Transmission (1994 - 1998) RPM's at 70mph ?

[pete97]

What should the RPM's be for my truck at 70mph? Just wondering. 5spd, stock tires, 3. 54's. Thanks Pete

 

[BigPapa]

Pete,



At a TRUE 70mph I'm right or a little below 2250. At indicated 70mph I'm just over 2000. These rpm's are a little higher than they were with the auto. I do have some 3rd Gen wheels with the factory BFG's. I think they're awful close to the same dimensions as the factory 16"'s.



Scott

 

[J Shocik]

When I'm doing 70, the tach shows 2000. My truck is mostly stock,& I'm running 265/75's on it instead of the factory 245's.

 

[EKlem]

With 245/75/16's, I spin 2100 rpms according to the tach at a true 70(according to gps). There is about a 2 mph discrepancy between my factory odometer and the gps with the gps reading lower. I noticed on my old truck that as the tread wore down and the tire had less circumference so the speedo became more optimistic that the discrepancy between the speedometer and gps increased.



You can actually do the math based on gear ratios and tire size to get the theoretical rpms that you should be spinning. You can do a google search and come up with all sorts of online gear ratio calculators.

 

[pete97]

Thanks for the info. This was the first time I had the truck on the interstate at 70mph since a converted to the 5spd from the Auto.