The Wheel Fitment, Tyre Stretch, Rolling Radius and Speedometer Error Calculator

Insert your existing wheel and tyre specs, and the desired size, and 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
656.8mm
656.8mm
Circumference
2063.4mm
2063.4mm
Poke
38.9mm
46.6mm
Inset
138.9mm
156.6mm
Speedo error
0%
0%
Reading at 30mph
30mph
30mph
Reading at 60mph
60mph
60mph
Ride height gain
0mm
0mm
Arch gap loss
0mm
0mm
Wheel Fitment Guide

Compared to your existing wheel, this new wheel will have an inner rim which is 17.7mm closer to the suspension strut. The outer rim will poke out 7.7mm 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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17x8 ET55 wheel options
WORK Wheels
SSR Wheels
JR Wheels
Rotiform Wheels
Rota Wheels
Bola Wheels
Fuel Wheels
3SDM
Concaver
7Twenty
BBS
1Form
Niche
Autostar
Dare
Motegi
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