[CronusTRD]

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.

 

[elgecko]

Looks mathematically sound to me.

 

[mudferret]

Yup, mathematically sound. Being a bit of a stickler for % diff calcs though, I'd say you're off by -12.9%, same shit.

 

[elgecko]

...and for the fuel economy calculation you can also go:

263 / 16.3 = 16.135 mpg

then 16.135 mpg x 1.129 = 18.216

 

[CronusTRD]

Cool..truck does better than I thought.

Not bad for Stock gears and 35" tires