There are a lot of theories floating around about the use of wheel adapters and spacers and their safety. Here are a few facts and thoughts that will help you make your decision whether to use them or not.
There are 2 primary uses for adapters:
- The first and most common use is to change the bolt pattern. Adapters are available that will change a 5-4.50″ to a 5-4.75″ or to a 5-5.00″, or the other way around. There are several companies that make adapters that can offer about any combination within reason. There are also adapters that will change a 4 hole pattern to a 5 hole. Changing a 5 hole to a 6 hole is pretty much out of reason. The drawback to using adapters is the thickness required to make them work properly. The minimum thickness required is about 1.125″ (depending on the length of your studs). This will move your mounting surface out 1.125″ and could cause some fender clearance problems.
- The second use is if you need to move your wheels out from the existing mounting surface. Adapters are available that have the same bolt pattern (i.e. 5-4.50″ to 5-4.50″). Adapters are the best way to accomplish moving your mounting face out. Adapters can allow you to move the mounting face from 1.125″ up to 2.500″. Anything over 2.500″ would require a little engineering, design and load calculation.
How they work:
Adapters are machined with a P.C.D. drilled with lug holes (60 deg. Conical Seat) (see TECH Stuff 4) to accept an open end lug nut. There are studs inserted in another P.C.D. between the lug holes (see drawing). The adapters are installed on the vehicle with lug nuts and tightened to the proper torque (TECH Stuff 4). Make sure the vehicle studs or lug nuts do not extend past the mounting surface of the adapter. The adapter becomes an extension of your original mounting surface. Then mount your wheel and tighten it to the proper torque.
Spacers have gotten a bad rap over the years. Some of the stuff is well deserved, but for the most part, spacers are not a bad thing and if used properly are a very useful tool to make your wheels fit properly. A spacer over 0.313″ (5/16) is not recommended. That makes it tough when you need to move the wheel out from 0.313″ to 1.125″. That’s no man’s land (between a spacer and an adapter). Oh well.
There are three basic rules to consider when using spacers;
- Always make sure you still have proper thread engagement of your lug nut and stud (TECH Stuff 4) after you have mounted the wheel on the vehicle with the spacer.
- Choose a spacer that has a lot of mounting surface. There are spacers being offered that are a “fit all” (4, 5 & 6 hole) type. These look like a piece of Swiss cheese and work about as well.
- Also make sure the material is adequate (billet aluminum is best – pot metal is worst).
Adapters and Spacers can be very handy tools that can help you get just the look you’re trying for with the wheels on your Rod. When used properly, they are safe and reliable.