Key Measurements & Other Things You Need to Know Before Buying Wheel Spacers

Many gearheads look to wheel spacers to increase the track width of their vehicles—and that can be advantageous for a handful of reasons.

For starters, wheel spacers can improve tire-to-chassis clearance. And that’s particularly beneficial for off-road trucks and SUVs that are fitted with oversized wheel/tire packages, where an extra fraction of an inch can mean the difference between serious tire damage and a fun day of trail riding.

a pair of Summit Racing Wheel Spacers
Summit Racing Hub Centric Billet Wheel Spacers are designed to increase the track width of the vehicle to improve clearance and feature a prominent lip in the centerbore to keep the wheel in perfect alignment with the axle or bearing hub. (Image/Summit Racing)

In addition to suspension clearance, many racers who are installing big brake kits look to wheel spacers so they’re able to fit a larger caliper into the wheel to improve their braking performance. And wheel spacers also come in handy to maintain your vehicle’s footprint when running narrower tires than stock.

Regardless of the reason, it’s critically important to understand a few things before buying a good set of wheel spacers.

What Are Wheel Spacers?

Wheel spacers go between the mounting surfaces of the wheel hub and the axle flange, and maintain the bolt pattern of the vehicle. In other words, wheel spacers are sandwiched between the wheel and hub.

hand holding two wheel spacers near rear wheel of a car
A wheel spacer simply fits in between the wheel and the mounting surface. These particular ones pictured here are relatively thin 1/8 inch universal spacers used to compensate when narrow snow tires replace this car’s wider summer wheels during the winter. (Image/OnAllCylinders)

The key thing to note, is that a wheel “spacer” keeps the lug pattern of the wheel consistent. If you want to change your car or truck’s lug bolt pattern (or even the lug count), then you’ll want to check out a set of wheel “adapters.” (It’s worth pointing out that most wheel adapters do add to the overall track width of the vehicle as well.)

It’s also important to know that wheel spacers can get pretty thin relative to a wheel adapter, with options available down to around 1/8 inch. Conversely, wheel adapters and some wheel spacers can easily run well over an inch thick.

wheel lug adapter mounted on a drum brake
Though the difference is subtle, this wheel adapter is changing a 5 x 4.75 inch lug pattern into a 5 x 5 inch bolt pattern. (Image/Jim Brightly)

Some Things to Know About Wheel Spacers

For starters, since wheel wheel spacers push the entire wheel/tire package out away from the vehicle chassis, you may run into clearance/rubbing issues with the car or truck’s inner fender. In extreme cases, you may need to trim back the fender and surrounding sheetmetal for ample clearance.

Another important point to consider is that, with the wheel moving off from the OE mounting flange, you’re now relying more on your wheel studs and lug nuts to carry the weight of the vehicle. For this reason, many wheel spacer manufacturers recommend a conical seat lug nut, as opposed to a flat shank washer lug nut design.

conical seat lug nut illustration
(Image/Summit Racing – Craig Artzner)

Speaking of lug nuts, there’s also a chance that your current wheel studs won’t be long enough any more to ensure enough thread engagement on the lug nut. So you’ll definitely want to double-check the length of your wheel studs when ordering wheel spacers.

Long story short, to ensure the best wheel spacer fitment, you’ve got to measure, measure, and measure.

How to Measure for Wheel Spacers

One of the best methods we’ve discovered to test and measure for the best size wheel spacers is to use a stack of ordinary hardware store washers on the wheel studs. (Alternatively, if you have a bunch of thin wheel spacers laying around your shop, you can use those in lieu of washers.) *

Starting with a modest stack of washers for a baseline, bolt the wheel on. Then, you test the side-to-side steering movement with the vehicle in the air. Next, slowly lower the vehicle and check for clearance/interference with the suspension compressed and settled to ride height. Gently bouncing and swaying the vehicle when it’s on the ground can be beneficial here too.

From there, you can add/remove washers to fine-tune the exact wheel spacer width you need.

* This is just for TEST FITTING only! Hopefully it’s obvious that you should never, ever, ever drive your car with a stack of washers or spacers on your wheel studs—ever.

stack of washers on a wheel stud for wheel spacer size test
Stack some washers on your wheel studs, bolt-on the wheel (temporarily!), and then test to ensure everything fits. Add/remove washers as needed to dial-in the perfect stack height, then measure it—voilà, you’ve got the correct wheel spacer width you need. As an added bonus, this method will also tell you if you’ll need longer wheel studs as well. (Image/OnAllCylinders)

Ordering the right size wheel spacers for your vehicle also means that you’ll also (obviously) need to know your wheel’s bolt pattern too—AKA, its lug pattern. If you’re not sure how to do that, read this: How to Measure Wheel Bolt Pattern and Backspacing

Again, if you want to change your wheel flange/hub bolt pattern, but don’t want to go through the task of swapping axles, a wheel adapter may help in certain scenarios.

Next, you’ll want to measure your hub pilot, to ensure the wheel spacer’s centerbore will be able to fit over it. See what we mean in this photo:

an illustration of how to measure & fit wheel spacers
(Image/Summit Racing – Craig Artzner)

Finally, you want to make measurements of all the things that could interfere with the movement of your specific wheel/tire combo. We alluded to it earlier, but understand how much clearance will be gained at the chassis—and how much will be lost inside the wheel well against the inner fender.

And make sure to account for wheel movement and articulation too. Remember, the front wheels will turn inside the wheel well, and all four will move up and down as the vehicle encounters bumps and dips in the road.

Again, the stacked washer trick outlined earlier can help here.

rear view of an AMC eagle SX4 with wheel spacers
This vintage AMC SX/4 is running wheel spacers that push the tires out away from the vehicle chassis. Though it’s an awesome look, note the strategic placement of the large fender flares—a necessary modification to keep muck and rainwater from being thrown up from the tires. Check out more of this rally-inspired AMC here. (Image/OnAllCylinders)

The good news is, wheel spacers are often available in many different widths for all of the common applications. So when you do finally determine the correct size you need, you’ll have no problem finding the best wheel spacers for your vehicle.

And when the right size wheel spacers are installed properly, they’ll deliver years of hassle-free service.

You can get a closer look at the pros and cons of wheel spacers and wheel adapters in this video with our pal Carl from Summit Racing:

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