Tire Size Calculator
Compare two tire sizes side by side: diameter, width, sidewall, circumference, gearing effect and speedometer error.
Alignment Toe Converter
Convert alignment toe between inches, fractions and degrees, at the tread or the rim, total or per wheel.
Gear Ratio Calculator
Cruise RPM at any speed, your effective ratio after a tire change, and the gear that gets the feel back.
Wheel Offset Calculator
Offset to backspacing and back, plus a side by side compare of two wheel and tire setups before you spend a dime.
Lug Pattern Finder
Bolt pattern, thread size and lug seat type for popular trucks and SUVs.
Wire Color Finder
Factory radio wire colors by year, make and model, with what each wire actually does.
Amp Wire Sizing Guide
Power and ground gauge, fuse size and speaker wire, figured from wattage and run length.
Engine Displacement Calculator
Cubic inches and liters from bore, stroke and cylinder count. Settles the bench racing arguments.
Compression Ratio Calculator
Static compression from bore, stroke, chamber volume, gasket thickness and deck height.
Carburetor CFM Calculator
The carb size your engine actually needs, from displacement, RPM and how the vehicle gets driven.
Fuel Injector Calculator
Injector size in lb/hr and cc/min from your horsepower goal, fuel type and duty cycle, for gasoline, E85 and methanol.
How these tools are built
The calculators run the standard published formulas, the same ones in the gear vendors' and carb makers' catalogs, and each page shows its math so you can check it.
The finders are different. Factory data like wire colors and lug specs is researched vehicle by vehicle from installer and fitment sources, cross-checked where a second source exists, and labeled when it rests on one. Where a verified answer does not exist, the tool says so instead of guessing. A wrong wire color costs someone an afternoon; we would rather show a gap.
Built and maintained by Pistons & Ink, the company behind Car Show Logic, Wrench & Lens and Whip Watchers. If a tool saves you a return or a re-order, that is the whole business model: you will probably be back.