I've had a few people contact me about these 1" wheel spacers as they wanted to know if they would work on a set of aftermarket wheels. The following will help illustrate why they work with factory wheels and what you will have to look out for if you choose to buy new wheels.
First up, this photo will show how the heads of the factory lug bolts stick out about 3/16" past the surface of the 1" wheel spacer. This can be a real problem and one that will prevent the proper installation of your wheels IF they don't have the means to clear the bolt heads.
As you can see here, the factory Trailhawk wheels have deep recesses next to the mounting holes and they provide the clearance the bolt heads need for proper installation.
If you choose to run a wheel that does not have recesses like the factory wheels have, you will want to get a set of 1.25" wheel spacers.
The following photos show how a set of 1.25" wheel spacers will keep the bolt heads below the mounting surface of the spacer.
For those of you who are interested in purchasing these 1.25" Wheel Spacers, I bought mine off of eBay and they came from a company who makes them in California. As in, the USA! Here is a link that should help you out: