Adjusting for 315/70/17
 

I went to the dealer today and adjusted my speedo.
Didn't seem to have an actuall tire chart for it so had to do the math.
Measured wheel travel that came to 8 feet.
5280/8 came to 660.

I have seen on here people saying 601.
Why would mine be so different?
Is the math wrong?

Because that circumference seems to be incorrect for a 315/70R/17 tire. 601 is the BFG rpm specification for the 315/70R/17. Tire calculator I use says circumference is 107.9 inches (8.9xxx feet). I used the 605 rpm from another owner that verified with GPS. Mine is as close as you can get. Try this link.

http://www.1010tires.com/TireSizeCalculator.asp

BF Goodrich spec sheets

http://www.bfgoodrichtires.com/asset...rain_ta_kd.pdf

The BFG website has the tire rotation numbers for all of its tires. Most people just look it up there and use that. Of course, in reality, it varies a bit depending on air pressure, tire wear, etc.

Sorry my memory sucks. Stock was 657 and he set it to 621.
They are arguing with me that I am wrong. I am taking them in the bfgoodrich chart and the calculater results.

Fun Fun

I went with 605, and it seems to be real close. If i am doing 70, the speado says 71....close enough