Wheel Calculators
Three calculators for the numbers that decide whether a wheel and tire fit. Pick the one that matches the question you are trying to answer.
Which calculator do you need?
Use the fitment calculator when you have a current wheel and a new wheel and want to see how the outer edge, inner edge, backspacing and overall diameter change.
Use the offset calculator when you know the wheel width and ET and want to understand backspacing or the effect of a spacer.
Use the tire size calculator when the wheel size is staying the same and you only need to compare tire height, diameter and speedometer error.
| Calculator | Question it answers |
|---|---|
| Fitment calculator | Will this wheel and tire package fit compared with the current setup? |
| Offset calculator | What does this ET mean in backspacing, and what does a spacer change? |
| Tire size calculator | How tall is this tire, and how does it compare with another size? |
Open the fitment calculatorOpen the offset calculatorOpen the tire size calculator
What the calculators do not know
The calculators work from the numbers you enter. They do not measure your brakes, fender shape or suspension travel, and they do not confirm tire load rating or hardware. Use them to narrow a setup, then check the car.
Frequently asked questions
Are the calculators free?
Yes. They run in the browser and do not require an account.
Do the calculators guarantee fitment?
No. They show dimensional changes. Brake clearance, suspension clearance, fender clearance, load rating and hardware still need a physical check.