Gearing Calculator
Ever wonder how far off your speedometer is with your new bigger tires? This info will only approximate your corrected speed and depends on the accuracy of tire size diameters (assumimg nothing but tire size has changed).
This calculator will get you back to a ratio that's closer to your original. Enter the values on the left and press Compute.
This formula is a nice way to get the tire diameter of those metric tires that are common on just about everything stock. For example a 265/75R16 would be around 31.6 inches tall. Enter the numbers into this form in the order you read them from the tire and press Compute.