What Is a Wheel Spacer, Wheel Adapter and Aluminum Wheel Spacer?

Literally, wheel spacer is a device to space the wheels outward from the wheel hub, and wheel adapter is a device for wheel adaption. They both are aftermarket accessories.

The wheel spacer is mainly, a) to move the wheels outward for wider stance and flush looking; or, b) to move the wheels outward for space for the upgraded calipers or etc; or, c) to adjust the offset of the wheels. And the wheel adapter is mainly to fit the wheels with different wheel sizes or different wheel bolt patterns from the original wheels. In practice, people may not seriously tell the name difference between the wheel spacer and the wheel adapter. Sometimes, when saying a wheel spacer, it refers to a wheel adapter in fact if to speak like a book.

Although in some markets, the relevant laws and regulations must be considered, and many people may still wary of the wheel spacer and wheel adapter out of various reasons, they are getting popular and offer a common, easy and safe way to make the vehicle wheels fit properly, and they are also beneficial for performance.

Wheel spacers and wheel adapters are normally made from steel or alloy aluminum, like alloy aluminum 6061 t6, 7075 t6 or other grades. Since the alloy aluminum has light weight and the it ensures the strength and reliability (if the grade is correct and true forged), the most in the market are aluminum wheel spacers and aluminum wheel adapters.

Based on the vehicle’s wheel fastening manners and the wheel spacer’s or wheel adapter’s thickness/width, different types/designs (of wheel spacers or wheel adapters) are made. The typical ones are,

1)  The Slip-on. Under such a type/design, 3mm and 5mm are most seen thickness/width. There are also a few 7mm, 8mm and 10mm. These wheel spacers have not centric lip to center the wheels. The wheels need to be centered by the wheel hub.

2)  The Bolt Type. Under such a type/design, the wheel spacer needs to be installed to the wheel hub by extended wheel bolts or extended wheel studs. 10mm to 25mm are the most seen thickness/width in the market. There are also some 3mm and 5mm for special purposes, and a few 7mm, 8mm, 30mm, 35mm. Different from the Slip-on ones, these wheel spacers have centric lip to center the wheels.

There are mainly two different kinds of wheel hubs. The first one, for example, the most European brand cars, the wheels are to be fastened by wheel bolts to the threaded bolt holes on the wheel hubs. Under this situation, when adding a bolt type wheel spacer, the wheel bolts need to be extended. The other, for example, the most American brand cars, the wheels are to be fastened by lug nuts to the pre-pressed wheel studs on the wheel hubs. In this case, when adding a bolt type wheel spacer, the original wheel studs normally have to be replaced by the extended ones.

3)  Stud type. The Stud type wheel spacers or wheel adapters have pre-pressed studs on them. They are to be fixed to the original wheel studs by open-end lug nuts provided together. The wheels are to be fixed onto the pre-pressed studs on the wheel spacers or wheel adapters by wheel lug nuts which normally need to be managed by the users. The thickness/width in the market is from 15mm up to 4” under this type/design.

4)  Inserted Nut Type. Wheel spacers or adapters under this type/design have nuts pre inserted on them. They are to be fixed to the threaded bolt holes on the wheel hubs by bolts provided. The wheels are to be secured to the pre inserted nuts on the wheel spacer or adapters by wheel bolts which need to be managed by the users. The most seen thickness is from 25mm to 50mm. There are also some thinner ones like 20mm, 23mm and thicker ones like 55mm, 60mm, 70mm, 75mm, 80mm, 90mm and even 100mm and 110mm.

5)  Bolt to Stud. Similar as the Stud type, the wheel spacers or adapters have pre pressed studs on them. Wheels are to be secured onto the pre-pressed studs on the wheel spacers or adapters by wheel lug nuts which need to be managed by the users. What’s different from the Stud type is that, the wheel spacers or adapters under this type/design are to be fixed to the threaded bolt holes on the wheel hubs by bolts provided. These wheel spacers or adapters offer the possibility of fastening the wheels to the wheel hubs with threaded bolt holes instead of pre pressed studs by desirable wheel lug nuts. The wheel spacer or adapter thickness from 15mm up to 4” can be seen in the market under this type/design.

6)  The Racing Derived. Wheel spacers under this type/design are based on the Slip-on or the Bolt Type but with even lighter weight.

The key parameters for a wheel spacer or wheel adapter are:

a)  Material. For example, 6061 t6, or 7075 t6, or steel, or any other;

b)  Type/Design;

c)  Bolt Patterns, including the bolt pattern for wheel hub side and it for the wheel side;

d)  Center Bore (for the wheel hub side);

e)  Wheel Centric Lip (if applicable);

f)   Thickness/Width (normally refers to per wheel);

g)  Extended Bolt Size (if applicable);

h)  Stud Size (if applicable);

i)   Mounting Bolt Size (if applicable);

j)   Mounting Lug Nut Size (if applicable);

k)  Finish Color (like anodized color or etc)