Wheel & Tire Calculators
Compare current and proposed wheel and tire dimensions. See changes in diameter, sidewall, inner clearance, outer position, scrub radius and speedometer reading on scaled diagrams, in millimetres or inches.
Wheel Offset Calculator
Compare a current and proposed wheel/tyre setup and see exactly how the geometry changes.
Tire Size Calculator
Compare two tyre sizes side by side - diameter, sidewall, circumference and speedometer effect.
Alternative Tire Sizes
Find standard tire sizes, including different wheel diameters, that keep overall diameter within a chosen tolerance of a starting size.
Wheel Spacer Calculator
See how a wheel spacer changes your effective offset and how far the wheel moves outward.
Scrub Radius Calculator
See how much a wheel offset or spacer change shifts your scrub radius from a known baseline.
Gear & RPM Planner
Compare road speed and engine RPM across six transmission gears using tire diameter and axle (final-drive) ratio.
Speed / RPM Converter
Convert road speed to engine or driveshaft RPM, or RPM to road speed, from tire diameter and one gear ratio.