For those who would like to push the wheels out several millimeters to adopt bigger suspension components, 12mm spacers will be a good idea. Countlessly successful practical cases prove that wheel spacers are exactly safe if you get a quality set and installed them correctly. Genuine 12mm spacers are made of top-quality material with the best machinery. Before leaving the factory, they have undergone a series of safety tests to eliminate any possible quality issues. So, you can always trust genuine wheel spacers.

Apart from the quality, proper fitment is essentially important. Make sure you have at least 12mm (1/2″) of wheel gap. Take a straight edge and place it against the outermost part of the rims/tires, then measure from the outside wheel to the fender line to see how much space you have available. If the value is above 12mm, then using 12mm spacers is very safe. If not, you may change to thinner spacers.

What 12mm Spacers are Safe BONOSS Forged Lightweight Plus Wheel Spacers for BMW G20 (4)

What Aluminum 12mm Spacers Do I Need?

There are various 12mm spacers that exist on the market. Most of them are made of steel or aluminum. Different materials perform differently. For most sports cars, SUVs, aluminum wheel spacers are safer than steel ones. Steel wheel spacers are strong but also heavy. The heavier weight will dampen acceleration, agility, and fuel efficiency. In the same conditions, steel will corrode a little faster than aluminum. A rusted wheel spacer means an awful risk.

On the other side, aluminum 12mm spacers are much better in corrosion resistance. Due to the property of aluminum alloy, the aluminum wheel spacers are protected by the naturally occurring oxide film, which brings them incredibly resistant to corrosion. This means they are not easy to corrode or oxidate which makes them safely work for long-term use. What’s more, under the same volume, aluminum 12mm spacers are much lighter than steel alternatives (on average, steel will be 2.5x denser than aluminum). It means that those aluminum spacers would add much weight to your vehicle. When it comes to wheel spacers, of course, a lighter one is far better than a heavy one.

What 12mm Spacers are Safe BONOSS Forged Lightweight Plus Wheel Spacers for BMW G20 (2)

What 12mm Spacers are Safe BONOSS Forged Lightweight Plus Wheel Spacers for BMW G20 (1)

Do I Need Extended Wheel Bolts for 12mm Spacers?

As a rule of thumb, a set of new extended wheel bolts is necessary to safely secure your 12mm spacers. If you are using 12mm spacers with factory wheels, then figuring out the proper size of longer wheel bolts will be easy. Simply add up the 12mm and the stock bolt length, the result value is the length of the extended bolts. Quality extended wheel bolts can add safety as well as maximize the appearance of your wheels.

BONOSS forged grade 12.9 extended wheel bolts are made of high-strength SCM440 alloy steel. The grade 12.9 means the minimum tensile strength of the wheel bolts is 1,220 MPa. And most originally equipped wheel bolts are grade 10.9 (about 1,040 MPa). The stronger the bolt is, the more force it can withstand more force before breaking. Changing to higher grade wheel bolts improves safety.