Dear Mweyand619,
I recently ordered 25mm simple hub-centric spacers for my back wheels. There are 2 paths you can take with wheel spacers. One is a spacer that has the studs pressed in and bolts to the factory studs, OR a simple spacer that uses the existing factor studs.
FYI, the studs on our Challengers are M14x1.5 thread, 50mm long (~2") (5x115mm bolt pattern). There is a limit to how wide a spacer you can use until you exceed the number of threads on the stud. The rule-of-thumb is typically a minimum of 1.5 x the bolt major diameter for the number of threads. For M14 bolts that works out to 21mm of thread length. For a 1.5mm pitch that's 21/1.5 = 14 threads. I don't know how many threads are available for the nut on a factory wheel, but would presume it's at least 14. Maybe on another posting someone knows the amount of available thread on the factory wheels. Let's say it's 25mm on the factory wheels. Then you could use a simple 11mm hub-centric spacer, not change a thing, and still be safe.
Once you go much wider, like I did, you need to use either the popular one piece adapter that bolts to the existing hub, or a simple hub-centric spacer.
Pros of the 1 piece adapter is you can just bolt it on, have a range of spacing options and can change it to a different size, or bolt pattern.
Cons of the 1 piece adapter, which are debatable, is how well the studs stay pressed into the 6061-T6 aluminum. There are stories of race cars that had wheels break or come off because the studs in these spacers failed. I think that is pretty rare, and for a street car it's probably not an issue. Another con is that you are using twice the number of nuts to hold your wheel on.
Pros of the simple hub-centric spacer is it does not have the press in studs, doesn't bolt on and comes off easily with the wheel.
Cons of the hub-centric spacer is it requires that you put in new wheel studs to accommodate the extra thread needed. Another con is the replacement stud spline diameter and length need to be identical to the factory stud you are removing. Dorman sells a huge variety of wheel studs, so finding a match is possible. Another con is the studs can get bent because they are so long. All the bending force is toward the end of the stud. I expect that with long studs (>3.5") this could be a big issue, but again it depends on the application.
With that said, I went with the cheaper, simple hub-centric spacer and bought longer wheel studs to replace the factory studs. IMO, a 1" longer stud is not going to be an issue for the street.
Wheel Adapters, Wheel Spacers, Hub Rings, and much more! | Motorsport Tech sells them.
Very Best,
Green Man
