NACvicSi

The stock Del Sol tire size is 195/60/14, but I'm currently running a 205/50/16. The tire size is 3.58% larger over stock per:
http://www.1010tires.com/TireSizeCal...?action=submit

I log my MPG on the fueleconomy.gov website, but seeing as the new tires are over sized I will have an incorrect reading. Would I simply take my mpg traveled, say 300, and multiply that by the 3.58% to get the miles to add? IE:

300 X 3.58% (0.0358) = 10.74

10.74 + 300 = 310.74 actual miles

Would this be the correct way. I'm fairly sure it is, but figured I would double check.

toyomatt84

iTrader: (1)

Actually, you use the circumference measurement difference, not the diameter difference. So, in your case, that would be 3.703%.

NACvicSi

Ok so go with the circumference difference and the rest was correct?

toyomatt84

iTrader: (1)

Yeah, to make it simpler just add the circumference difference + 1 and multiply it by the mileage covered.

Your example:
300 miles x 1.03703

Its the same as adding 300 and 3.703% of 300 together.