Discussion Starter · #1 ·
I am trying to figure out what yall's rpms are at 60 mph with what gearing. I wanted to compare it to mine to see if my torque convertor is slipping.
The math says 1,940 RPM.60 MPH has my engine turning approx 1900-2000 RPM. That's with 245/75/16 tires, 4:10 rear.
The math shows that your speedo is off by a coupla MPH. You should see about 1,525 RPM at 60 MPH but only about 1,475 RPM at 58.I have been running 1525rpm's for 58mph with the 265/75r16 with the 3:55 rear end in the van.
The rpms in what the scangauge would be showing, +/-.
Is the math right?
Most tire size calculators, including that one, are off by a few percent. They assume the tire really is 245mm wide, and that the sidewall is 75 percent of 245mm, and that the wheel diameter at the bead is exactly 16". But tire makers don't make their tires to the exact numbers assumed by the tire size calculators.