The choice of alloy wheels is overwhelming. You can only hope to maintain an overview if you’re able to distinguish the individual models from each other. This is where the rim designation comes in. You can use it to clearly identify rims from different manufacturers and figure out which one fits to your car. But what do the individual numbers and letters in the rim designation mean? We’ve summarized the most important terms for you here to make it easier for you to choose the right wheel.
Take a closer look: letters and numbers
The rim designation is a raised digit-letter sequence providing information about the wheel rim dimensions, the bolt circle, and the composition of the rim flange. It is located around the wheel hub hole or on the spokes. But if you aren’t used to reading rim designations, the cryptic letter and number sequences are more likely to cause confusion than to give you an “aha!” moment. We’ll explain the individual key numbers of the rim designation with an example: the RIAL LUCCA in polar-silver:
8.0 x 18 OS45 5 x 112 PCD
The value of 8.0 indicates width of the rim in inches, meaning the area between the rim edges on either side.
In our example, the rim diameter is 18 inches.
OS refers to the wheel offset. It determines the distance from the flange to the center of the wheel and, thus, the position of the wheel in the wheel well. In this case, the offset is 45 millimeters.
PCD stands for the pitch circle diameter. This is the circle of holes in which the alloy wheel’s wheel bolts are mounted. Our example wheel has 5 mounting holes for wheel bolts. The number of these holes must correspond to the number of holes in the vehicle’s wheel hubs. Last but not least, our example wheel has a bolt circle diameter of 112 millimeters. Again, the figure for the wheel must match that of the vehicle.
If you’d like to learn more, check out our previous article on the composition of a wheel rim. It explains all the terms like bolt circle, rim width, and other components in more detail.
Your safety comes first
Did you find the perfect wheel? Then the first thing to do is ensure that the wheel rim designation corresponds to the manufacturer’s specifications. You can see which wheels are approved for your car – i.e. which wheel dimensions are permitted – in the vehicle’s owner’s manual.
You should always pay special attention to key figures such as the diameter of the bolt circle and the number of mounting holes when making a purchase. If they don’t match, the alloy wheel cannot be properly and safely mounted on the hub. Selecting the right offset is also enormously important for driving safety since it can influence the car’s track width and steering geometry.
We support you with your selection
Our Wheel Configurator helps you keep the search for the ideal alloy wheel as straightforward as possible. After just a few clicks, it provides an overview of all the wheels that can be mounted on your vehicle.
Now you’re more than well equipped. With our tips in mind, nothing stands in the way of your new alloy wheel purchase.