TireCalculatorPro

Tire Size Calculators

Free tire size calculators — compare sizes, convert measurements, calculate diameter, pressure, volume, speedometer error, and more.

Tire Size Comparison Calculator
Compare two tire sizes side by side — diameter difference, speedometer error, and fitment compatibility.
Tire Size Converter
Convert between metric (225/45R17) and standard inch tire sizes instantly.
Tire Diameter Calculator
Calculate the overall diameter of any tire from its metric sidewall code.
Gear Ratio & RPM Calculator
Calculate how a tire size change shifts your effective gear ratio and RPM at speed.
Tire Size Difference Calculator
Find the diameter, height, and width difference between any two tire sizes.
Rim Width Chart by Tire Size
Look up the recommended rim width range for any tire width from 155mm to 355mm.
Speedometer Error Calculator
Calculate exactly how much your speedometer reads fast or slow after a tire size change.
Tire Size by VIN Lookup
Look up the OEM tire size for any vehicle using its 17-character VIN number.
Wheel Offset & Backspacing Calculator
Calculate wheel offset and backspacing — and see how changes affect track width.
AWD Tire Size Tolerance Calculator
Check if your tire size difference is within safe limits for your AWD system.
Plus-Size & Winter Downsize Calculator
Calculate plus-one or plus-two upgrades, or find the right downsize for winter wheels.
Tire Pressure After Size Change
Find the correct inflation pressure after switching to a different tire size.
Tire Aspect Ratio Calculator
Calculate sidewall height in mm from any tire's aspect ratio — and compare across series.
Tire Sidewall Height Calculator
Calculate exact sidewall height in mm for any tire size — e.g. 225/45R17 = 101mm.
Tire Height Calculator
Calculate total tire height in inches or mm, compare two sizes, or find all metric sizes matching a target height.
Tire Diameter & Gear Ratio Calculator
See how changing tire diameter shifts your effective axle ratio and top speed.
Tire Diameter to RPM Calculator
Calculate engine RPM at any road speed for a given tire diameter and gear ratio.
Tire Diameter Chart
Reference chart of overall diameters for 200+ common tire sizes in mm and inches.
PSI to kPa Converter
Convert tire pressure from PSI to kilopascals (kPa) — with pre-computed common values.
Bar to PSI Converter
Convert bar to PSI for European tire pressure gauges and placards.
Tire Pressure by Vehicle
Find the manufacturer-recommended tire pressure for 200+ vehicles by make and model.
Cold Weather Pressure Drop Calculator
Calculate how much tire pressure drops per degree of temperature fall.
Tire Pressure Chart by Tire Size
Recommended inflation pressures for common passenger, SUV, and LT tire sizes.
Load Range Inflation Guide
Correct inflation pressure for each tire load range — C, D, E, F, and G.
Tire Air Volume Calculator
Calculate air volume inside any tire in litres, gallons, and cubic inches.

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Frequently Asked Questions