You're most welcome! Again though, this is really a starting place (that is pretty close). Your truck may weigh more or less than the weight the tire manufacturer assumes for their table. You may also inflate your tires higher or lower than the cold inflation pressure they assume.
And, even speed has an effect! At 75 mph, the speed limit on the interstates here in AZ, the centrifugal force (and heat) on the tire will cause it to "expand" and increase its "rolling radius" compared to the same tire driven at a more sedate speed of say 55 mph. You can see this "radius expansion" quite easily when a drag racer does a "burnout" to condition his tires. Of course that is an extreme rotational speed, but there will be an effect like this even at lower speeds. This is one reason I don't care for the "measure one revolution of the tire on the driveway" method. I think the result will be low.
So, you are probably within about 2 mph of an "exact" value for speed and distance at 2483mm. If you can do a LONG run like I just did (for 70 miles), you can make it a bit more accurate for YOUR particular weight/speed/pressure setup.
- Jack
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