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Wheel Size

Wheel Size Explained:

Alloy wheel sizing is generally a simply science, width and diameter. All alloy wheels have 2 main measurements these are always shown in imperial sizes as inches and also tend to always be written in the same way. If you look on the Race and Road website or on an actual alloy wheel you will see the following example of measurement 7.5x17”.


The first is the measurement of the wheels width. The width of an alloy wheel is measured from the inside of the rim where the tyre fits the wheel. So if you measure a 7.0” wheel from outside edge to outside edge you will find it measure 8.0”, but if you measure from bead seat to bead seat, where the tyre sits, you will see it measures 7.0”.

The second is the measurement of the wheels diameter. Again the measurement can be deceiving is you were to measure a 17” alloy wheel on the outside from its furthest point to point it will measure around 18”. As with the width of the wheel the diameter is measured from the points at which the tyre sits on the wheel.
This rather confusing information can be cleared up a little by looking at the alloy wheel cross section diagram below.

Alloy Wheel Size Explained - Technical Help

Why Fit Bigger Wheels?

Apart from the obvious aesthetic improvements by fitting larger alloy wheels there are other advantages. By fitting larger alloy wheels you generally benefit from greater widths and clearances. This can mean, more direct steering responses, better road holding and much improved cornering. This is due in part to the wider than standard wheel but also the reduction in un-sprung weight from OE steel wheels. Other major advantages from weight reduction are improved fuel economy and safer braking. Having a width increase means you have greater clearance with in the wheel to fit larger brakes. Race and Road can tailor make alloy wheel and tyre packages to suit you and your vehicles requirements. See our “On Car Viewer” to get an idea of the sort of package that would suit your vehicle. This will show the range of sizes and style suitable for you vehicle.

All this information may seem a lot to take in but don’t worry Race and Road will deal in full with the technical side of your purchase.


For more information relating to the offset of our products, please contact us.

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