Quote:
Originally Posted by jeongyun
I hope you adjust odometer reading when you calculate the MPG.
there's fairly large difference in circumferences between two sizes. about 4.5%
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If you didn't you still got about 25mpg. Since your tires are about 4.3% off, next time you fill up multiply your mileage by .957 like this; because your new tires are 95.7% the diameter as your old set.
260miles/10gallons=26mpg. - wrong
260miles*.957=252.2. 252.2/10gallons=25.2mpg
Although, if the old tires on the truck aren't the original size, find the original size and google search a tire size calculator to find out the percentage they're off. I have to do the same thing with my ford ranger except backwards cuz I put taller tires on to bring the rpm's lower while cruising.