Quick question re: revolutions per mile

[EasyDriver]

Originally Posted by anonymous user

If my OEM tire (goodyear eagle ls) was rated at 880 revs per mile, and my new tire (hankook rs-2's) are rated at 915 revs per mile, then does that mean that i've been calculating my MPG's incorrectly?

So hypothetically lets say a round number like 400 miles on a fillup, of 10 gallons of fuel. This would net me 40mpg's.

So the ratio of the new tire (915/880= approx 1.03977% change) would change it to 400 milesx1.03977= 415.9 miles? So then that would change my MPG from 40 to 41.59?

What i'm trying to aSK is does the speedo recalibraTE for my new tires, or do i need to multiply it (1.03977) every tank in this case?

thank you!

http://www.miata.net/garage/tirecalc.html try this site for the info you want....