Installing wheels spacers is common within the tuning scene. They are a cheap and easy way to improve wheel fitment and increase the track width of your car. However, they are also a fast and easy way to ruin the geometry of your car and can badly affect your handling.

The Negatives

The main issue with a wheel spacer is that it moves the wheel to a wider position whilst the rest of the suspension arms remain in the same place. In particular, the king pin inclination axis remains in the same place. Therefore, fitting a wheel spacer moves the wheel outboard and alters the scrub radius of the car. It is important to know whether your car currently has negative or positive scrub radius and ideally how much it has. Fitting a wheel spacer will increase the positive scrub radius at the front wheels which has some unfavourable consequences.

If your car already has a bit of positive scrub radius then the wheel spacer will increase it. An increase in positive scrub radius increases the forces on the steering rack under braking conditions. Any bumps in the road will also be amplified through the steering wheel, making the steering jerky and more unpredictable. Twitching wheels when braking can cause the tyre to lose grip and ultimately can cause the wheels to lock up and slide. An increase in positive scrub radius also causes the wheel to gain positive camber when the wheels are being turned, reducing grip in corners on the front wheels and producing understeer.

If your car has the more favourable set up of negative scrub radius then installing a wheel spacer can cause bigger issues. The outward movement of the wheel can make a negative scrub radius become zero. This is the worst position for it to be in. A zero scrub radius can cause squirm. This is where a scrubbing action occurs on both front tyres in opposite directions which can create unpredictable handling in corners and can lead to understeer too.

Secondly, installing wheel spacers on a car increases the leverage on the wheel bearing. The larger the spacer, the larger the leverage becomes. This reduces the life of the wheel bearing as they are not made to take leverage forces and can therefore wear faster, increasing rolling resistance and power loss of the car.

Finally, the wheel spacer moves the wheel further away from the damper mounting point. This means that the wheel will have a larger effect upon the damper and will act upon it with more leverage. This effectively makes the spring and damper softer and less effective on the wheel. This means that the car can roll more on corner entry and exit and feel generally softer out on track or on the road.

The Positives

However, there are some positive aspects to fitting wheel spacers to your car that can prove beneficial. Moving the wheels outboard increases the track width of the car. The increase in track width also lowers the roll centre of the car and therefore increases the amount of cornering force that the car is able to carry through its tyres. Due to being able to manage an increase in cornering G force, it means that it is possible to corner at higher speeds.

Installing the spacer on the rear wheels means that the negative aspects take less effect because the scrub radius effects are not present at the rear wheels. Therefore if your car is suffering from oversteer then installing wheel spacers might be a quick and cheap way of reducing that.

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16 Comments

  1. Interesting read and backs up what I have said about wheel bearing pressure. Two things, one, will altering the offset of wheels do this same thing?
    And two, how would you suggest effectively increasing track width without compromising the handling?
    Thanks and look forward to your reply

    1. Hi Stig, thanks for the comment. Yes increasing your wheel offset without increasing the tyre width will act the same as a spacer. The best way we can suggest to increase track width is by installing adjustable length arms to move the wheel and hub assembly outboard, increasing track width. However, if you must be willing to check your geometry settings after doing this as further adjustments and modifications may be required when this is done. Thanks

  2. Hi. I have a Ford Focus year 2015, sligthly oversteering. Installing only on the rear wheels the spacers, 5mm or 10mm, can I reduce oversteer? Thanks.

    1. Hi Cesare,

      Thanks for your comment. Installing a wheel spacer could help with the oversteer as it will increase your rear track width helping with LLT. However, you would be better observing your tyre behaviour and trying to solve the oversteer by optimising rear camber, toe or damper settings.

      Thanks

      Suspension Secrets

  3. Hi. Thanks for reply. I see that my car has a rear track large 1559mm, front track 1544mm. Can be this one of the reasons for its oversteering behaviour? If I install spacers only on the front, in order to equalize the rear and the front track, can be a valid solution?
    Excuse me for my English.

    Regards.

    1. Hi Cesare,

      Installing spacers on the front will provide more track width and therefore likely reduce understeer and increases the tendency to oversteer. However, it is worth noting that installing spacers will affect multiple other aspects of your geometry so you should try to solve the problem using roll bars, dampers and geometry before installing spacers.

      Thanks

      Suspension Secrets

  4. Hallo,
    nice article there. One question: would a positive scrub radius of 7-8 mm on the REAR axle be noticeable or too much? Car in question is a BMW 6 series running 275/30/20 wheels with an original ET of 44 whereas the upgraded wheels would have an ET of 37. I guess for the rear axle this variance is not so problematic correct?
    Look forward to your advice. Thanks and Regards

    1. Hi Christian,

      Yes the effects upon the rear axle are not as bad as the front axle. The main negative for installing on the rear axle is the increased loading on the wheel bearing. However, you will benefit from increased rear track width.

      Thanks

      Suspension Secrets

  5. Are 15mm spacers go8ng to cause issues for my 2014 Audi RS5?

    1. Hi Mark,

      Wheel spacers will always affect geometry and alter handling and response slightly. However, the smaller the offset the less the effect so 15mm spacers wouldn’t cause too much of an issue.

      Also you wouldn’t feel the effects of a spacer as much with general road driving as you would out on circuit.

      Thanks

      Suspension Secrets

  6. I’ve mounted 10 mm Eibach spacers in the front of my BMW 3 series F31 (from 8×19 ET36 to ET26). I’ve noticed a fraction less understeer, maybe placebo effect. :). Could these cause some long term damage on my suspension, tires,…? Thanks.

    1. Hi Jan, thanks for the comment. The reduced understeer will be a result of the now wider track width across the front wheel which will reduce understeer slightly. The installation of the spacers will have altered your scrub radius which will alter how your wheel pivots. It will likely cause slightly more scrub to your tyres and make them wear faster when turning the wheel. However, it will take a while for a noticeable difference to occur.

      Thanks
      Suspension Secrets

  7. Wrong post, sorry. Thanks for the advice, suspension secrets. Grtz Jan

    1. Hi, i had stock 205/65r16 with 6jj 50offset alloys & tires, Now i have uograded to 215/65r16 with 6.5j 40offset alloy & tyres, the scrub radius of positive 8mm has increased, its a rear wheel driven toyota body on frame MUV will it affect the handling & what about suspension life, is it going to take a toil.

      1. Hi Jeevan,

        The increase of 8mm will slightly affect handling in that the feedback through the steering when applying brakes will increase. Furthermore, any bumps in the road pushing back on the tyre will be amplified through the steering wheel. The increase will slightly increase the load upon the wheel bearing too but this should be quite negligible.

        Thanks

        Suspension Secrets

        1. Thank you very much.

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