4x4ord wrote:
I don't remember exactly what I said on the other thread but it seems to me that I might have told you that if your tac and speedo are right your tires are low on air or bald and need replacing. With 235/80 r 17 tires and 4.10 gears your engine will be running very close to 1910 rpm at 70 mph. It looks like your speedo and gps agree ... I'm sure your tires aren't worn out, so my guess is that your tac is off.
In my experience, most tachs aren't dead on. They are generally off by 50 rpm or so versus my app that is reading from the ECM in just about every vehicle I have owned from my Ram to my old Fords. As with speedo's or most anything manufactured, they are on a bell curve and can be off +/- a few percent.
