Machined discs that mount between the wheel hub and wheel, pushing the wheel further outward to widen the vehicle's track.
Wheel spacers are machined aluminum or steel discs that sit between the wheel hub and the wheel itself, effectively moving the wheel outward from the hub face. The result is a wider track (the distance between left and right tires), which can improve handling by increasing stability and reducing body roll. Visually, spacers give the car a wider, more planted stance and fill out fender arches that might otherwise look empty with stock offset wheels.
Spacers come in two main types: bolt-on spacers (which use extended lug studs or the vehicle's existing studs) and hub-centric spacers (which include a machined center bore matched to the hub diameter). Hub-centric spacers are preferred because they ensure the wheel centers on the hub rather than on the lug bolts, reducing vibration risk. Slide-on spacers pressed against the hub and secured by the wheel's own lug nuts require sufficiently long studs and are generally considered higher risk for daily driving.
Thickness matters. Small spacers (5-10mm) are relatively low risk on properly engineered hubs. Large spacers (25mm or more) stress wheel bearings and may require extended-thread lug bolts. Safety depends on quality, installation torque, and regular torque re-checks. High-quality brands like Eibach, H&R, and Spidertrax are preferred over cheap unbranded units.