RIM PROFILE

Rim profile is the shape of the wheel between the inner and outer kerb edges. It features a well which allows the tyre to be fitted to the rim. This is essentially a cut-out which gives the inside edge of the tyre somewhere to go when its outside edge is being fitted.

Most standard wheels have a shallow and progressive tyre well. This makes tyre fitting easy, but the way a tyre well ‘dishes’ can reduce the amount of space available to accommodate larger brake discs and calipers. Motorsport wheels tend to use an aggressive rim profile to maximise the amount of space inside the rim, but the downside to this approach is more difficult tyre fitting.

It’s worth noting how different applications attract their own rim profiles. In fact, there are standardised measurements for different rim profiles to highlight their compatibility with specific tyre sizes. The most common automotive rim profile is known as ‘J’ (hence a 7J alloy), but there are other designators applied to agricultural, motorcycle and heavy machinery wheels.