Quote:
Originally Posted by Sid 6.7
There is a difference of 3.19% in the rolling diameter of the new tires from the old. So multiply your trip mileage by 1.0319 to get your actual mileage traveled.
|
Thanks!!
I knew there had to be some math/engineering wizards out there. 
After plugging your adjustment into my spreadsheet, I show that my last tank was
37.947 MPG and my average since the new tires is
36.729 MPG.
I hope that it improves, and I think it will since I'm now adjusting my speed for the speedometer error and getting lower rpms on the highway.