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Tyres and Wheels

5 tools

Which Tyres and Wheels tool do you need?

ToolWhat it answers
Tire Comparison CalculatorOverall diameter of a metric tire is the rim size plus twice the sidewall, where sidewall = width × aspect ratio.
Tire Diameter CalculatorOverall tire diameter equals the rim diameter plus two sidewalls, where each sidewall is the section width times the aspect ratio.
Tire Pressure CalculatorTire pressure changes with temperature because the air inside is a fixed volume of gas.
Tire Rotation ChartFront-wheel-drive cars with non-directional tires use the forward cross: fronts move straight back, rears cross to the opposite front.
Tire Size CalculatorA metric tire size like 225/45R17 means a 225 mm section width, a sidewall 45% of that width, and a 17-inch rim.

All tools

Tire Rotation Chart

Find the tire rotation pattern for FWD, RWD, AWD or 4WD with non-directional, directional or staggered tires, plus the odometer reading when the next one.

Tire Comparison Calculator

Compare two metric tire sizes side by side: overall diameter, sidewall height, revolutions per mile and the speedometer error a size change causes.

Tire Diameter Calculator

Convert a metric tire size such as 205/55R16 into overall diameter in inches and mm, plus sidewall height, circumference and revolutions per mile.

Tire Size Calculator

Decode a metric tire size such as 225/45R17 into sidewall height, overall diameter, circumference and revolutions per mile, or compare two sizes.

Tire Pressure Calculator

Work out how a tire's gauge pressure changes when the air temperature moves, in psi or kPa, using absolute pressure and Gay-Lussac's gas law.