Free Tire Size Comparison Calculator
The tool people actually need: will this size change height, width and speedometer — and is it inside 3%?
- The tire rests on the ground, so half of any diameter change goes downward and only the other half lifts the vehicle.
- A diameter one inch larger raises the vehicle half an inch, and takes half an inch of fender clearance away.
- That same change shifts the speedometer and revolutions per mile, because the tire covers more ground per turn.
- Width is a separate problem: a wider tire can rub even when the diameter is perfect.
What it does
Compares two sizes on every dimension that matters: diameter, width, sidewall, circumference, revs/mile, plus the change in ride height (half the diameter change).
How to use it
Enter the size on the car now and the size you are considering. You can paste complete sizes. The drawing is to scale: taller and wider tires are actually drawn taller and wider.
How to read the result
Shops generally like diameter within 2% of stock. 2–3% is a common stretch with a speedometer check. Over 3% often needs a lift, rolling the fenders, or a re-gear — and it is outside what we mark as generally accepted. Width is a separate clearance problem: a wider tire can rub even when diameter is perfect.
What this does not calculate
The 2% / 3% bands are industry practice, not law. We cannot see your fenders, lift, control arms or mud flaps. The scale drawing is the two tires only — it is not your wheel well.
Does not simulate rubbing, alignment, load index, or whether a specific brand in that size exists.
Questions
- Why is 3% the usual limit?
- Around 3% overall diameter is where speedometer error, ABS/traction calibration and fender clearance start to stack up. Many installers will still do 2–3% with a warning. Past 3% is a modification, not a swap.
- Does a taller tire raise the truck by the full diameter change?
- No. Ride height changes by half the diameter change — one sidewall. A tire 1" taller raises the body about 0.5".
- What about stretching a tire on a wide rim?
- This tool compares tire sizes, not how a given tire sits on a rim. Use Recommended rim width for that.
Related tools
- Tire Size Chart — Metric & InchesCommon sizes by rim diameter — metric, exact inches, and a link to run the numbers.
- Free Tire Size CalculatorPaste a size. See the real dimensions — not just the numbers on the sidewall.
- Speedometer Error CalculatorTaller tire: you are going faster than the needle. Shorter tire: you are going slower.
- Plus Sizing CalculatorBigger rim, shorter sidewall — without accidentally lifting or lowering the car.
Estimate — not a fitment approval.
