the toolbox
calculators for people who do their own math.
quick answers for wheels, gears, compression, and unit conversions. free, no login.
tire size calculator
compare tire sizes, check wheel fitment and stretch/bulge, calculate offset and clearance, and convert metric ↔ flotation.
gear ratio & speed
speed in every gear at any rpm, rpm at cruise, and the diff ratio to restore gearing after a tire change.
displacement & compression
engine displacement from bore and stroke, plus static compression ratio from chamber, gasket, deck, and piston specs.
wheel offset & backspacing
convert offset to backspacing and frontspacing, and see how a spacer changes effective offset and poke.
unit converters
torque, pressure and boost, temperature, and AFR ↔ lambda.