At GMP Performance, we have spent years playing with wheel offsets. This experience helps us offer only the best and most technically sound solutions for wheel accessories. Wheel spacers and wheel bolts are the simplest way to improve the aesthetics of any wheel package. They can even make a car look lowered! There are a couple technical points that we touch on with each wheel spacer kit. Below is a quick description to help you achieve the proper spacer and wheel bolt fitment.

Wheel Spacers
Wheel Spacers move your wheels and tires outwards so they are more flush with the fender—instantly giving your vehicle the perfect stance. High end sports car manufacturers use every millimeter of fender space available in their design for the best looks and highest performance and so should you.

What spacers do I need?

Beveled/Chamfered Spacers and Vehicle Hub-Height
Certain wheel spacers have a beveled or chamfered edge to accomodate the vehicles hub height. The spacers are designed like this to accomodate hub-heights that may be taller than the width of the spacer. For instance, a 10mm spacer must have a beveled/chamfered hub-center for a vehicle with a 15mm hub-height.

The hub-height and beveled/chamfered spacers must be taken into consideration when fitting spacers because the OEM wheels have been designed for the vehicle specifically and the spacers must match so that the wheel will sit flush on the vehicle's hub. An improper bevel/chamfer fitment will cause a gap and may result in vibration. In addition, it may result in a wheel coming loose because the bolts cannot be torqued correctly. Below is an example of two bevel/chamfer variations:

Wheel Spacer Fitment Notes:

Vehicle wheel hubs must be cleaned prior to install. Over time, rust and corrosion can build up on the hubs of your vehicle. The spacers are sold for a very specific center-bore which is measured in fractions of a MM and any build-up will prevent a proper fitment. We generally clean the hubs with sandpaper if it has light build-up or even a wire brush for older hubs.

Wheel bolts
Wheel bolts are available in a wide variety of size, pitch, seat design, length and the appropriate lug wrench socket size. It is of utmost importance to measure the correct length for your wheel bolts. Most manufacturer's want 6-8 turns on a bolt. Be sure and measure the length of the bolt with the following diagram.

In addition, wheel bolts are available in either cone (Conical) seat or ball seat. This is a description on the mounting surface of the wheel bolt. The ball seat bolts also have a radius specified by each manufacturer. The radius must match in order to get the proper fitment.

NOTE: Keep a set of your vehicle’s Original Equipment lug nuts or bolts in the trunk just in case you ever need to use your factory spare tire, which must always be installed with the Original Equipment lug hardware.

Free Length
We refer to the "free length" as the measurement of the OEM wheel bolt that sticks out past the back of the wheel pad. To measure this, simply remove a wheel and insert a wheel bolt. Measure the bolt that protrudes from the back of the wheel. This "free length"is the amount of threads that will go into the hub of your vehicle. In order to get the correct bolt for spacers, you simply add the desired spacer amount to the free length of the OEM bolt to get the desired new bolt length. So if your OEM 29mm bolt has a freee length of 20mm, and you are adding a 10mm spacer, you need to 39mm wheel bolt. Additionally, if you are swapping to aftermarket wheels, be sure and check the "free length" on your OEM wheel bolts and make sure that you have the same amount on your new wheels. If not, you will need a new set of longer, or even shorter, wheel bolts.