Wheel & Tire Calculators
Choose the measurement you need: tire size, wheel offset and backspacing, clearance, or speedometer error. Each tool explains its inputs, directional results and limitations.
Choose by task
Changing wheels and tires
Wheel & Tire Fitment CalculatorOpen calculator for Wheel & Tire Fitment CalculatorChanging only the tire size
Tire Size Comparison CalculatorOpen calculator for Tire Size Comparison CalculatorConverting offset and backspacing
Wheel Offset & Backspacing CalculatorOpen calculator for Wheel Offset & Backspacing CalculatorComparing inner clearance and outer wheel movement
Wheel Poke & Clearance CalculatorOpen calculator for Wheel Poke & Clearance CalculatorAdding spacers
Wheel Spacer CalculatorOpen calculator for Wheel Spacer CalculatorDecoding one tire's dimensions
Tire Size CalculatorOpen calculator for Tire Size CalculatorChecking speedometer change
Speedometer Error CalculatorOpen calculator for Speedometer Error CalculatorExploring sizes for a larger rim
Plus Sizing CalculatorOpen calculator for Plus Sizing CalculatorConverting a tire size
Tire Size ConverterOpen calculator for Tire Size Converter
All calculators by category
Related entries, such as offset and backspacing, share one tool. See the methodology for conventions.
Complete Fitment
1 tools
The whole setup: wheel position, tire dimensions and speed effects together.
Wheel & Tire Fitment Calculator
Compare the dimensional changes between current and proposed wheel and tire setups.
Wheel Fitment
3 tools
Understand wheel width, mounting position, backspacing, spacers and edge movement.
Wheel Offset & Backspacing Calculator
Convert wheel offset and backspacing with measured overall width, or compare two wheel positions.
Wheel Poke & Clearance Calculator
Compare inner and outer wheel-edge movement relative to a reference setup.
Wheel Spacer Calculator
Calculate effective offset and the dimensional effect of spacer thickness.
Tire Size
2 tools
Read a tire specification or compare the dimensions of two sizes.
Tire Size Calculator
Calculate tire width, diameter, sidewall, circumference and revolutions from one metric size.
Tire Size Comparison Calculator
Compare two tire sizes and their dimensional differences.
Speed & Geometry
1 tools
Estimate speedometer changes from tire diameter; complete tire geometry lives in Tire Size.
Speedometer Error Calculator
Calculate the relative speed change caused by a different tire diameter.
Conversions & Upgrades
2 tools
Translate size notation and explore dimensional alternatives for larger wheels.
Plus Sizing Calculator
Explore nominal tire-size alternatives when changing rim diameter.
Tire Size Converter
Convert metric and flotation tire notation in both directions, with explicit rounding and equivalence limits.