About WheelSignal
WheelSignal is a small set of free calculators for drivers, enthusiasts and people doing their own vehicle research. The aim is simple: understand the numbers behind your wheels.
What the calculators do
- Tire size calculator: Sidewall, diameter, circumference and revolutions for any metric size, with a side-by-side comparison and speedometer difference.
- Wheel offset calculator: See how a new width, offset or spacer moves the inner and outer wheel edges relative to the hub.
- Fuel cost calculator: Trip fuel and cost in L/100 km, km/L, US or imperial MPG, with tolls, parking, cost per person and a two-vehicle comparison.
- Gear ratio calculator: Theoretical road speed at a given RPM, or RPM at a given speed, across every gear, with a speed-versus-RPM chart.
How they work
Every result comes from numbers you enter: tire size markings, wheel widths and offsets, fuel economy and prices, gear ratios. There is no vehicle database, VIN lookup, live fuel-price feed or product catalogue, so nothing is assumed about your vehicle.
Each calculator page explains its formulas and assumptions and includes a worked example. Unit conversions use exact definitions, such as 1 inch = 25.4 mm, 1 mile = 1.609344 km, 1 US gallon = 3.785411784 litres and 1 imperial gallon = 4.54609 litres. The calculation code is tested against values worked out independently by hand.
The calculators run in your browser. What you type is not sent to WheelSignal or anyone else.
How to use the results
Results are nominal, theoretical estimates intended for understanding and comparison. Real tires, wheels and vehicles vary. WheelSignal does not check fitment, clearance, load ratings, legal compliance or safety, and it is not a substitute for the vehicle manufacturer’s information or advice from a qualified professional.
Funding
The site is free to use. It currently shows no advertising and contains no affiliate links. If that changes, this page and the privacy policy will say so.
Spelling
Page addresses use the American spelling “tire”. In the UK, Australia and elsewhere it is written “tyre”; the calculators work the same for both.
Last updated .