What is the difference between aluminum and steel spacers?

When shopping for wheel spacers, one of the material choices you will encounter is between aluminum and steel. Both materials are used in quality spacer manufacturing, but they have meaningfully different characteristics that make each better suited to certain applications. Here is a breakdown of how the two materials compare across the factors that matter most for wheel spacers.

Aluminum Spacers

Aluminum is by far the most common material used in aftermarket wheel spacers for trucks and SUVs, and for good reason. The combination of properties aluminum offers makes it well suited to the demands of wheel spacer applications across a wide range of use cases.

The most significant advantage of aluminum over steel in a wheel spacer application is weight. Aluminum is significantly lighter than steel, which means aluminum spacers add minimal unsprung weight to the wheel assembly compared to an equivalent steel spacer. Unsprung weight is the weight of components not supported by the vehicle's suspension, and keeping it as low as possible is beneficial for ride quality, handling responsiveness, and the suspension's ability to follow the road surface. For most truck and SUV owners, the weight difference between aluminum and steel spacers is a practical benefit that makes aluminum the default preference.

Aluminum also has excellent natural corrosion resistance due to the oxide layer that forms on its surface when exposed to air. This makes aluminum spacers well suited to year-round use in climates where road salt, moisture, and other corrosive elements are a regular concern. Quality aluminum spacers are typically made from billet 6061-T6 aluminum, which is a specific aluminum alloy that offers an excellent combination of strength, machinability, and corrosion resistance and is widely used in aerospace and automotive applications where structural reliability is important.

One consideration with aluminum spacers is that aluminum is a softer material than steel, which means it requires careful and proper installation to avoid the risk of galling or thread damage at the hardware interfaces. Using the correct torque specification, proper lubrication on threads where recommended, and always using hand tools rather than power tools helps ensure aluminum spacers are installed correctly and maintain their structural integrity over time.

Steel Spacers

Steel spacers offer greater raw tensile strength than aluminum spacers of the same dimensions, which makes them a consideration for extreme heavy duty applications where maximum structural strength is the priority over weight savings. In applications involving very heavy loads, extreme off-road use with large impacts, or other conditions that put unusually high stress on the wheel and hub assembly, the higher strength of steel provides an additional margin of structural integrity compared to aluminum.

Steel is also more resistant to deformation under very high clamping forces, which can be relevant in applications where extremely high torque values are used. For the vast majority of truck and SUV applications including daily driving, towing, hauling, and recreational off-road use, however, quality 6061-T6 aluminum spacers provide more than adequate strength and the weight and corrosion advantages of aluminum make it the more practical choice.

The trade-offs of steel spacers are meaningful for most applications. Steel is significantly heavier than aluminum, adding more unsprung weight to the wheel assembly. Steel is also more susceptible to corrosion than aluminum without proper protective coatings, and in environments with road salt, moisture, and harsh conditions, steel spacers that are not adequately protected can develop rust over time. Rusting hardware and spacer surfaces can make future removal more difficult and in severe cases can seize the spacer to the hub or the wheel studs.

Which Material Is Right for My Setup?

For the overwhelming majority of truck and SUV owners, quality billet 6061-T6 aluminum spacers are the recommended choice. They provide ample strength for all but the most extreme applications, offer meaningful weight advantages over steel, and handle the corrosive conditions of year-round road use better than steel without requiring additional protective treatment.

Steel spacers are worth considering for very specific heavy duty applications where extreme strength is the primary concern and weight is not a significant factor. For standard lifted truck builds, stance modifications, and recreational off-road setups, aluminum is the practical and well-proven standard choice.

Quality and Machining Matter More Than Material Alone

Regardless of whether you choose aluminum or steel, the quality of the machining and manufacturing is just as important as the material itself. A poorly machined spacer of either material can introduce runout or imbalance into the wheel assembly, affect the hub-centric centering of the wheel, or have inadequate thread engagement at the stud holes. Choosing spacers from reputable manufacturers with documented material specifications and quality standards is always the right approach, and the team can help recommend quality options for your specific application.

Have Questions About Spacers for Your Setup?

If you have questions about spacer materials, sizing, or which option is right for your specific vehicle and intended use, the customer support team is happy to help. You can reach out through the Contact page on the website and a team member will be glad to assist.