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Discussion Starter · #1 ·
Is my math right? I'm trying to find out my actual mileage per gallon, taking into account larger tires.

Formula I am using:

Speedometer Adjuster (with oversize tires)
(New Tire Diameter / Old Tire Diameter) * Speedometer MPH = Actual MPH

So for me its:

(35"/31") = 1.129

1.129*55mph = 62.095

To figure out my adjusted mileage, I got 263 miles (unadjusted on stock gearing, according to odometer) to my last tank of gas.

so that is 263 * 1.129 = 296.927 miles (adjusted)

Divide that by 16.3 gallons it took to fill up tank,

296.927/16.3 = 18.216 miles per gallon. (adjusted)

Man, my odometer/speedometer are way off.
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