Site information

A measuring tool. Not a guarantee.

Fitment North is a free public calculator for wheel offset, wheel width and tyre size. It shows how declared geometry moves, in millimetres, so you can see the change before you buy.

What Fitment North is

It is a geometry aid for drivers and fitment professionals. You enter the sizes on the wheel and tyre, or use a comparison page that already holds those sizes. The site then calculates position, clearance movement, rolling diameter and an estimated speedometer difference from those numbers alone.

Local, manual calculation

The public calculator runs in your browser. The wheel and tyre values you type are not saved in browser storage and are not sent to Fitment North unless you separately submit a partner request. There is no live vehicle-database lookup on this free public version. If licensed lookup is added later, that change will be described before it is switched on.

What the numbers cannot prove

A calculated change is not a guaranteed fit. The tool does not inspect brake clearance, suspension travel, hub bore, fastener seat, load or speed ratings, bodywork or modifications. Confirm the exact setup with a qualified retailer or installer before ordering or fitting parts.

Who it is for

Drivers comparing a current setup with a proposed one, often on a phone beside the car, and professionals who need a clear millimetre answer without forum guesswork. There is no account and no charge to use the calculator.

Questions

Write to support@fitmentnorth.com. Partner introductions and coverage applications use the forms on the calculator and partners pages.

Last updated: 13 September 2026