You can adjust the axle track of your car with wheel spacers. Wheelspacers, also called wheel adapters or spacers, are fitted between the wheel rim and the hub. More precisely put, they are fitted over your car’s holding bracket. Wheel spacers are used to create extra clearance between the wheel and the wheel hub assembly. This way, spacers increase the distance between the wheel and the wheel hub assembly and thus increase your car´s axle track. This distance between the rim and the hub is called the offset and is expressed in ET value (millimeters). Wheel spacers matches with a vehicle’s bolt pattern and fit over the existing studs, allowing the wheel to be mounted normally.
Wheelspacers are often used when you want to install larger tires. Besides the obvious benefit that they help give your car a unique look, wheelspacers also help to increase vehicle performance because the vehicle´s handling improves. In addition, wheelspacers also make it possible to install larger brakes. When you want to install larger tyres and rims to your car, and you do not use wheel spacers, there is a chance that the wheel will start rubbing.
What is the offset (ET-size)?
When you want to install other rims to your car which are wider than your initial ones, you need to take the offset into account. Offset is the distance from the hub mounting surface to the centre line of the wheel, to the wheel's true centreline. It is measured in mm and can be either positive or negative. A positive offset means the hub-mounting surface is closer to the outside edge of the wheel, while a negative offset means the hub-mounting surface is closer to the inside edge of the wheel. Effectively, offset value says something about how deep the hub goes into the rim, or how close the rim sits to the hub assembly components. Basically, at the centre line we are at 0mm or 0 offset. 0 Offset refers to the mounting surface being lined up with the centre line of the wheel. If we move toward the hub/away from the face, we are going into negative offsets. If we move toward the face/away from the hub, we are looking at positive offsets. For example, if a wheel's mount is 35mm away from the centre line it’s at +35 offset.
The next two things you need to understand are back space and front space. Back space corresponds to how far the back of the wheel will go in. Preferably without rubbing on the suspension. Front space is essential to know how far the wheel comes out from the hub. In this case, you don't want it to come out past the fender.
Practical applicability? The ET number indicates how many millimetres the centre line of the wheel deviates from the wheel hub. The lower the ET, the more the rim sticks out. You can use wheel spacers to adjust the ET size. With spacers the ET size of the wheels is lowered (!) and the wheels are placed further outside. A wheel spacer 10 mm thick will lower the ET value by 10.
The offset is stamped on a wheel as an ET value, which refers to the German phrase Einpress Tiefe. To get things clear, offset is the same as Einpress Tiefe. The ET size is also called IS-value, and both are the same as offset.
What wheelspacers do I need?
In addition to offset, you also need to take bolt pattern (also called bolt circle) and the diameter of the wheel hub (also called center bore) into consideration. The wheel hub diameter is important to ensure that the wheel spacers fit around the hub. Next to wheel hub,you need to pay attention to the bolt pattern. The bolt pattern refers to an angement of the lug holes and the centre of the wheel. And in this case also the assembly of the wheel spacers to the hub. The bolt pattern is represented with two numbers; the number of lug holes x the distance between them across the centre of the wheel also called the pitch circle diameter (P.C.D.). P.C.D. is the diameter of the circle which passes through the centre of all the studs, wheel bolts or wheel rim holes. A correct bolt pattern is essential in order to assemble the wheel spacers to the hub. The bolt pattern is specific to a vehicle and can’t be changed. It has to be the exact same pattern on the wheel. Wheel spacer specifics are often referred by lug holes, bolt pattern and center bore diameter. Wheel spacers 4 x 100 - 57.1, for example, refers to 4 lug holes, the diameter is 100 mm and the center bore diameter is 57.1.
Please, also pay attention to the length of the wheel nuts and bolts. If you are installing wheel spacers, it is recommended to use longer wheel bolts. Because of the increased width, less thread will remain using the same bolts decreasing the locking strength. In some cases,you will also need spigot rings. Spigot rings ensure that the wheel spacers are better secured and the wheels are better held in place. With some wheel spacer kits, centring rings are included.
Buying new wheelspacers
Buying new wheelspacers or wheel adapters is quick and easy at Winparts. You can easily filter using specifics such as hub hole diameter, bolt pattern and the desired offset. At Winparts you will find H&R wheel spacers, but also from Autostyle and TPI. You can also find other accessories for your wheels such as wheel nut covers, tyre stands, tyre repair and tyre pressure and profile gauges.