I noticed on another thread that trucks w/ stock tires are running 2000 rpm at 71-72 mph. I'm running 67-68mph at 2000 rpm. The only thing different I see is the other trucks have auto transmissions. I'm wondering if my rpms are calibrated incorrectly for the stock tires. What mph are others w/ stock tires getting? thanks.

 

you must have read my replies. mine is running right at 72MPH at 2000 rpms. i do have the 48RE transmission with 3.73 gears and have checked it with a gps so i figure it must be pretty accruate. don't know why the 6 SP would read any different?


britt

 

Easy answer - the 6 spd and the auto have different top gear ratios.

 

With my 315/70R/17 tires, 3.73 gear and 48re at 2000 rpms I at 78mph cruise set and level road.

The OD gear ratio in the 48re is 0.69:1. The 6th gear ratio in the NV5600 is 0.73:1. These are the listed ratios in the DR Service manual.

This would account for a different speed at the same engine rpm at normal cruising with the same rear end and stock tires.

 

I have the same set up, 3.73 rear end, 6 speed and OEM tires. At 2000 RPM I'm racing down the road at a neck wrenching speed of 67-68 MPH, so you are right in there.

Blair