The Alloy Wheel Fitment, Tyre Stretch, Rolling Radius & Speedo Error Calculator

Insert your existing alloy wheel and tyre specs, and the desired size. The outcome is shown on the diagram.

Your existing setup

Existing Tyre
Existing Wheel

Your new setup

New Tyre
New Wheel
Your Results

Existing

New

Diameter
614.6mm
703.5mm
Circumference
1930.8mm
2210.1mm
Poke
50.9mm
56.2mm
Inset
126.9mm
96.2mm
Speedo error
0%
-12.64%
Reading at 30mph
30mph
26.21mph
Reading at 60mph
60mph
52.42mph
Ride height gain
0mm
44.45mm
Arch gap loss
0mm
44.45mm
Wheel Fitment Guide

Compared to your existing wheel, this new wheel will have an inner rim which is 30.7mm further away from the suspension strut. The outer rim will poke out 5.3mm more than before.

The strut shown in the diagram is for show only. Don't worry if the wheel looks like it fouls!

Bear in mind most tyre manufacturers vary slighty from the specs, and that it could be dangerous to run tyres on wheels they aren't designed to fit.

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15x6 ET20 (+-5mm) wheels
WORK Wheels
SSR Wheels
JR Wheels
Rotiform Wheels
Rota Wheels
Concaver
Motegi
Fuel Wheels
Bola Wheels
3SDM
7Twenty
2Forge Wheels
1Form
Niche
Autostar
Dare

Will They Fit - The No.1 Online Alloy Wheel & Tyre Fitment Calculator

Use our comprehensive online wheel size calculator to visualise different alloy wheels and tyre combinations. Calculate your offset, compare tyre stretch, rolling radius and more. Compare your new and existing setup and our tool will show you key measurements for accurate wheel and tyre fitment.

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