Your existing setup

Existing Tyre Width
Profile
Diameter
Existing Wheel Width
Offset
Measurement Guide
The Right
Numbers?

Your new setup

New Tyre Width
Profile
Diameter
New Wheel Width
Offset
Measurement Guide
The Right
Numbers?

Existing

New

Diameter 631.9mm 645.2mm
Circumference 1985.2mm 2027mm
Poke 42.6mm 100.7mm
Inset 122.6mm 140.7mm
Speedo error 0% -2.06%
Reading at 30mph 30mph 29.38mph
Reading at 60mph 60mph 58.76mph
Ride height gain 0mm 6.65mm
Arch gap loss 0mm 6.65mm

Popular 18" wheels

Compared to your existing wheel, this new wheel will have an inner rim which is 18.1mm closer to the suspension strut. The outer rim will poke out 58.1mm more than before.

Wheel Fitment Guide

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

Wheel Spacers and PCD Adapters
Will They Fit Measurement Guide