"Let's buy the more expensive ones and save some cash." This line is always a lie unless it's you trying to sell the wife on a Jeep part or the wife trying to sell you on some new curtains. Just because you are saving more money doesn't mean you are spending less.
Well, in our case, it did. We knew that we were going to be swapping axles in our '94 YJ, and we knew that we were going to end up running a 5-on 5.5-inch bolt pattern when we were done. That was the easy part. The hard part was that we were also putting a new set of rims and tires on it to replace our old ones. We did the math, and a set of wheel spacers came out cheaper than a set of rims. Once we added on the cost of mounting and balancing, it was a no-brainer.
We ordered a set of the Spidertrax Off-Road 1 1/4 -inch wheel spacer/adapters (PN WH-004) and put them on our YJ. This allowed us to go from the stock 5-on-4.5-inch bolt pattern to the 5-on-5.5-inch that we were aiming for. However, there are other reasons to run spacers, and not all spacers are adapters. While it's perfectly OK to do this at home, there are a few things to look out for.
There is a lot of buzz about the spacers being bad for wheel bearings or ball joints, but it just isn't so. The wheel spacer acts just like a rim with less backspacing would. Of course, once you start talking about 3- or 4-inch spacers (for 6 or 8 inches of track width increase) that's another story.
Regardless of what spacer you get, don't get any kind of cast unit. Also, never stack spacers to get the width you want. Figure out what width you need and order spacers for that application. Find a unit that has been spun or machined out of 6061T6 or equivalent aluminum stock.
Pay attention to track-width changes from the spacers. In our case, we went to a wider rim with a wider tire and used spacers to fit them. Our YJ ended up almost 10 inches wider from the outside of tire to outside of tire. Of course, we are swapping axles and will deal with the excess width at that point, but if we weren't, we'd have to run a 12-inch flare to cover the tires.
Hub-centric is another big buzzword in the market of wheel spacers. While it is true that for some vehicle manufacturers it matters, for a Jeep it can also be a burden. For example, the Spidertrax spacers are so well made that our rust-and-paint-covered front hubs didn't fit inside the spacer easily. We had to scrape off a ton of paint and rust in order for them to fit. Jeep wheels are lug-centric or located by the lugs. Any good spacer for a Jeep will also be lug-centric at the minimum. Centering on the hub can be beneficial when running larger tiresand/or wider spacers to keep stress off the lugs.
Possibly the most important thing with any wheel spacer is to tighten it down to the specified torque. Too much torque, and it might crack or strip out the lug. Too little, and your wheel could fall off when driving. So follow the approved tightening pattern until all the lugs are tight. Then, after 50 to 100 miles check the spacers again. Yeah, it sucks, but it's better than the wheels falling off.
Another benefit we got from the Spidertrax spacers was the ability to see exactly where the tire was going to end up in the wheelwell when flexing and turning. We are looking to cut some junkyard axles down for this YJ and were undecided what width we wanted them to be when we were done. Now that we've run these spacers for a while with the tires we are going to be using, we know exactly how wide of an axle we want.
Keep spacers in mind next time you are looking to swap axles, rims, or tires. Whether it's so you can bolt up different rims and tires or just to figure out what width axles you want to run, they can save you money in the long run by not having to do things twice.