Tyre Lab: Size & Pressure

Know your tyres. Own the road.

Tyre Lab brings a tyre size calculator, tire pressure converter and wheel size comparison into one clear, offline toolkit for motorists, cyclists and 4WD owners.

COMPARE TYRE SIZES

Enter original and alternative metric sizes to compare nominal diameter, sidewall height, circumference, revolutions per kilometre and ground clearance changes. See how a different diameter affects estimated speed at the same speedometer reading. Switch between km/h and mph.

BUILT FOR BICYCLES, TOO

Compare bicycle ETRTO sizes such as 40-622 and 47-622. Bicycle geometry is an approximation; measured rollout is more accurate for cycle computer calibration.

CONVERT PRESSURE INSTANTLY

Convert PSI, kPa and bar as you type. Copy a conversion and choose your preferred dashboard unit.

RECORD YOUR OWN READINGS

Enter readings from your pressure gauge and see them in a clear dashboard with an entry timestamp. These are manual records, not live TPMS or temperature data. Colours identify wheel positions, not safe pressure levels.

KEEP YOUR FAVOURITE SETUPS

Save up to 12 tyre size comparisons in your garage. Calculations and local presets work offline, without an account. Loading a setup clears old pressure readings so you can enter fresh measurements.

UNDERSTAND YOUR LOAD

Read guidance on cold pressure, manufacturer limits and tyre/rim compatibility. Compare measured loaded mass against a manufacturer-specified total mass limit. This is a mass difference check, not a pressure or individual tyre-capacity calculator.

USE THE RIGHT SOURCE

Tyre Lab does not recommend inflation pressures. Follow the vehicle placard and manufacturer guidance for your exact tyres, rims and loading. Nominal size comparisons do not establish safe fitment or legal approval. Speed estimates assume calibration for the original tyre and exclude existing instrument error. Links to NHTSA, Schwalbe and Continental provide further reading and require internet access.

Recent changes:
First release: metric and bicycle ETRTO comparisons, speedometer estimates, circumference and clearance calculations, pressure unit conversion, manual readings, local garage presets and sourced load guidance.