When taking a closer look at tuned sports cars, we can often notice that many vehicles seem to utilise a wheelbase that is wider than the factory-produced model. This is achieved by the use of spacers, helping to push out the wheel and car tyre. What are car spacers and how do they work? Read more about car wheel spacers’ pros and cons and understand what changes their use implies.

part of wheel close-up

Wheel spacers influence the car’s profile and proportions. Many feel such a change makes a vehicle appear much more compact and aggressive. From an aesthetic point of view, certainly, the use of spacers ensures a car stands out from its peers.

From a driving perspective, an extended wheelspace also improves the car’s handling. In other cases, you may also find that car wheel spacers are a necessity. For instance, when you need to install larger brakes, spacers are used to generate this extra room. They can also be useful when the offset of a selected wheel is too high or deep.

In these cases, the spacers help provide a safe distance between the braking system, specifically the calipers and discs, and the suspension system.

wheelbase comparisonAn example of how a vehicle can look with the addition of wheel spacers

How to check the maximum spacer width?

If you want to know the maximum spacer width, the easiest and most effective method is to measure the distance between the edge of the wheel arch and the tyre. This will provide you with the maximum safe distance between the car tyre and the hub, thus giving you the maximum size of the spacer.

However, you should also consider leaving some gap between the tyre and the car’s bodywork. As a result of this, spacers with the exact same width as the distance measured - using the formula above - should not be used. Because of this, you should always consider the tyre width and size of the models you are using. 

wheel spacer measurementSpacer width measurements

How to install wheel spacers?

The wheel spacer diameter must be adjusted to the diameter of the hub, as the hub sidewall and the side of the spacer must form a coherent whole that is flush and smooth. Remember that the formation of visible indentations in this area, resulting from a difference in diameters, is unacceptable.

Similarly, the bolts of the spacers screwed into the hub must not protrude above the surface of the rim. When screwing longer bolts into the hub, make sure that there is no risk of damaging the elements already inside the hub, such as the ABS sensors.

Ultimately, the wheel spacer must be fitted loosely to the hub and no significant levels of resistance should be evident.

wheel spacer mountingOnce installed, the spacer diameter must be flush with the diameter of the existing hub

What kind of bolts are needed for wheel spacer installation?

When installing wheel spacers, you must ensure that the bolts are correctly screwed to the hub, thus fitting the wheel on the spot. Many experts claim that this condition is only met if at least 10 to 12 mm of the screw thread is screwed into the hub socket. If the bolt is not screwed in this way, there will be a risk of a thread failure.

The recommended screwing depth, as well as the number of turns for a range of screws with different thread pitches, is present below. Please remember that the number of turns also applies to any nuts used.

  • M12x1.25 = at least 8 turns = approx. 10 mm of thread
  • M12x1.50 = at least 6.5 turns = approx. 10 mm of thread
  • M12x1.75 = at least 6.5 turns = approx. 12 mm of thread
  • M12x1.25 = at least 9 turns = approx. 12 mm of thread
  • M14x1.50 = at least 7.5 turns = approx. 11 mm of thread

According to various automotive experts, the selected bolt length for pass-through spacers should be longer, by 50% of the spacer’s width, than standard variants.

proper bolt length for installing wheel spacersNew bolts need to be longer than your existing ones

How to choose the right spacer type

A wide range of types of wheel spacers can be installed in virtually any car, as long as the individual needs of the vehicle owner are taken into account.

The car width, for instance, can be increased from 5 to 90 mm on each side. For such a wide selection of sizes, various solutions can be applied.

Here, we will go through different types of wheel spacer constructions, which may help you in making the correct decision when looking for a solution appropriate for your car.

Type 1: Pass-through spacers without a centring collar

Known as “pass-through spacers”, these options do not have a centring collar. Due to their low thickness, the rim is centred on the centring collar of the hub. Such spacers should be fitted with the use of bolts which are longer than the standard options.

wheel spacer without centring collarAn example of installing pass-through spacers without a centring collar

Type 2: Pass-through spacers with the centring collar

If you decide to extend the car’s wheelbase by 6 mm or more, a wheel spacer with a centring collar should be used. This is necessary because the hubs’ centring collar gets covered by the spacer itself.

It is essential to use adequately longer bolts during this installation. In terms of length, these bolts should have an additional amount equal to 50% of the spacer width. Do not use standard bolts, as these will not be long enough!

wheel spacer with centring collarAn example of installing pass-through spacers with a centring collar

Type 3: Spacers fastened to the hub

Spacers fastened to the hub, also known as hubcentric wheel spacers, offer more opportunities for wheelbase extension. This product is supplied with the bolts needed to mount the spacer to the hub, rather than relying on the standard bolts.

Apart from the bolt sockets, the spacer has threaded holes which are used to mount the wheel - this time using the standard bolts.

wheel spacer fastened to hubAn example of installing typical spacers fastened to the hub

There is also an alternate, namely a more developed version of this spacer type. In this variant, the threaded holes (normally used for bolts) are replaced with pins which the car wheel is then mounted on. Such solutions can be used to extend the wheelbase by up to 90 mm.

alternative wheel spacersAn example of installing alternative spacers fastened to the hub

PCD changing spacers

You should also be aware of a specific type of spacer known as PCD changing spacers. Due to the ability to change the spacing of the bolts, these spacers are used on wheels with a non-standard pitch circle.

The installation and design, however, does not differ much from the construction of a normal hub-fastened spacer, as discussed above.

What are spacers made of?

The most typical materials used for the construction of spacers are aluminium alloys, similar to that used in car rims, alloy wheels and hubcaps, as well as magnesium alloys.

Additionally, the surface of a spacer is also hardened via anodisation, a surface treatment for metals. It involves electrolytic production of a thin oxide film, significantly increasing the hardness and scratch resistance of the material. The use of light alloys also reduces the weight by up to 70%, when compared to traditional steel counterparts.