With bigger wheels is your mileage meter off, so that when it shows 100 miles have you really gone 101 or so? Do you get better mileage because the circumference of the wheel is more, or is it worse mileage? Just checking. Ron

 

With a larger wheel/tire combination, your car will go further with each rotation of the wheel (larger diameter = larger circumference = longer distance traveled per revolution). This means that your odometer will report a number that is LESS than the actual mileage traveled by a small amount.

Imagine this scenario:

You have 15s with 195/60 tires and replace them with 17s with 225/50 tires (not that you would, but for this argument, let's pretend).

The total diameter of the 15s, including the tires is 24.2126 inches; the cirumference is 76.06613 inches.
The total diameter of the 17s, including the tires is 25.85826 inches; the circumference is 83.23612 inches.

Assuming 100mph for 100 miles, to make the figuring easier, your 15s would rotate 833 times. while you 17s would rotate only 780 times, about 94% of the number of rotations of the 15s. Because your speedometer relies on counting rotations (not neccessarily of the wheels, but the tranny - the relationship is direct however), your speedometer would read 94mph when you are actually travelling 100mph.

Did that make ANY sense?

 

And to answer your original question, you would travel 100 miles when your odometer only says 93.

 

See, told you MCO people were the smartest!!!!!! (...but I am probably not one of them. )

 

IQQMINI,Thanks.....Brilliant. Would your engine strain more, therefore giving you worse gas mileage?

BTW I have 17'' wheels and love them. Ron.

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