Join the Car Talk Community!

Does putting bigger wheels on your car make the speedometer...

RSS
Dear Tom and Ray:


Does putting bigger wheels on your car make the speedometer read faster or slower? I've got a bet on this.
Jim

RAY: The speedometer will read slower, Jim. The speedometer reading is based on how many times the axle turns. With bigger wheels, the axle will turn fewer times to cover the same distance, so the speedometer will think the car is going slower.

TOM: If you don't believe us, put on some larger wheels, bring your car up to the "speed limit" on your speedometer, and drive through your favorite local radar trap (preferably with a smile and a wave). I'm sure the nice police officer will be happy to confirm that you were, indeed, going faster than your speedometer led you to believe. In fact, you'll even get a written confirmation of this should you need it to settle the bet.
Tags (Browse All)

You must be logged in to leave a comment. Login / Signup
Support for Car Talk is provided by:

Donate Your Car,
Support Your NPR Station

...and get a tax break!

Get Started

Find a Mechanic


Go



Submit


Rocket Fuel