Tire/Wheel Combination Calculator

This page will calculate the comparison of two tire/wheel combinations.

Change any one of the "Initial Information" parameters to see the affects.

Initial Information
Current Planned
Section width (millimeters):
Tire aspect ratio:
Wheel diameter (inches):
Wheel width (inches):
Wheel offset (mm):
Fitment Results
Current Planned
Tire height (inches):
Ride height difference (inches): - N/A -
Tire width difference (inches): - N/A -
Tire rollout (inches):
Wheel/Tire Aspect Ratio (%):
Wheel diameter difference (inches): - N/A -
Wheel width difference (inches): - N/A -
Wheel offset difference (mm): - N/A -
Wheel Inboard increase (inches): - N/A -
Wheel Outboard increase (inches): - N/A -
Tire /w Wheel Inboard increase (inches): - N/A -
Tire /w Wheel Outboard increase (inches): - N/A -
Effect on tire track (inches): - N/A -
Effective Gearing Results
Current Planned
Wheel rpms at mph:
Actual speed with new tire/wheel combination:
Speedometer Error (%):
Engine rpms with differential gear and transmission gear ratio:
Effective differential gear ratio:
Effective 1st gear ratio with a ratio:
Effective 2nd gear ratio with a ratio:
Effective 3rd gear ratio with a ratio:
Effective 4th gear ratio with a ratio:
Effective 5th gear ratio with a ratio:
Effective 6th gear ratio with a ratio:
Effective Reverse gear ratio with a ratio:


FORMULAS:

tire height = wheel diameter + (2 X (section width / 25.4) X (aspect ratio / 100))

rollout = tire height X PI

wheel rpm = (vehicle speed / 60) X (5280 / (rollout / 12))

engine rpm = wheel rpm X rear gear ratio X transmission gear ratio

255/50-17
255 Section Width Total width of the tire at the sidewalls in millimeters. This is measured from the outside of the sides of the tires when mounted and not the tread or rim width.
50 Aspect Ratio Percentage of the section width that is the sidewall height. For this example the 255mm section width multiplied by an aspect ratio of 50 gives a sidewall height of 127.5mm
17 Wheel Diameter Wheel diameter at the tire mounting surface in inches.
Authored by Rick Tolan.
Copyright © 1998 by Tolan-Hoechst Family.
Last Updated: