Your Ultimate Tire Companion

Calculate exact internal air volume of any car tire in liters — useful for sealant, pressure planning, and size comparison.

Find out how much your speedometer reads off after a tire size change, and your real speed at any indicated speed.

Estimate the loaded rolling radius of any P-Metric tire — affects speedometer, gear ratios, and ground clearance.

Convert between wheel ET offset and backspacing in inches — essential before buying aftermarket wheels.

Compare front and rear tire diameters for staggered setups — checks AWD drivetrain tolerance (3% limit).

Find the minimum, ideal, and maximum rim width for any tire section width — prevents sidewall damage and blowouts.

Compare two P-Metric tire sizes side-by-side — shows diameter, sidewall, circumference, and speedometer difference.

Estimate the contact patch area (grip footprint) of your tire from load and inflation pressure.

Find the right tire pressure for cars, trucks, motorcycles, bicycles, RVs, and golf carts.

Instantly convert tyre pressure between PSI and kPa for UK, EU, and Australian vehicles.

Decode the DOT code on your tire sidewall to find the manufacture date and get safety warnings for tires over 6 years old.

Compare your spare tire diameter to your primary tires — critical for AWD and 4WD drivetrain safety.