I recently checked the fuel mileage of my 91 Montero with 33x12.5 tires (14.7 mpg). I was pretty bummed until I realized that this is not accurate since the number of miles traveled with 33ö tires is not accurately reflected by the odometer.

Has anyone devised a conversion factor to correct the fuel mileage when driving with 33s? Would the same conversion work on the speedometer? IÆm assuming it would.

Thanks

1991 Montero LS, fading red paint
Front and rear limited slip differentials
95 SR Rear Springs, torsion bar crank, 137,650 miles
33x12.5 ProComp Mud Terrains, Bushwacker Fender flares
3 litre V6 with new heads