Use our speedometer calculator to find the differences in speedometer reading and actual speed when changing to a tire size other than stock.
Speedometer calibration, or knowing how fast you're going, can be pretty important. We all know a ticket is about the biggest buzz kill on earth! So if you're about to get bigger tires than stock or already have them installed, its time to calculate your true MPH. Your speedometer is reading how many revolutions your tires are making not how fast they are spinning. When you go to bigger tires the circumference of the tires is larger, meaning the distance around the tire is longer. Thus, with each revolution you are traveling further than before. Therefore your actual speed is higher than your speedometer reads. Or lower if you have gone with a smaller tire than stock. Our speedometer calibration calculator will get you the answer you are looking for. Enter your original tire size, your new tire size, and then play with the miles per hour to see how much faster you are going at different speeds.
If you would like to see more speedometer calibration speeds at a time, visit our tire size comparison page to compare different metrics of tires and get multiple speedometer calibration readings at once.