Wheel adapter or spacer Tips: Recommendations from a former ASE master mechanic and tire shop operator:
When shopping for wheel spacers or bolt pattern adapter/spacers, avoid anything over 2" thick because things happen to the geometry of your steering and wheel bearing/front end wear increase rapidly the farther your wheels are out spaced beyond factory engineered design specs. Especially when already running reverse offset wheels to begin with such as the off-road community regularly does.
Try to find spacers or adapters that are forged CNC alloy, hard-coat anodized to prevent corrosion and are centric to index off of the axle flange center hub. Or at minimum, the wheel center hole on factory wheels if possible. Most of the time you can't use the aftermarket wheel center hole since it is usually machined larger than stock for the wheel to fit several makes and models of vehicles.
Always try to get adapters/spacers that have high grade studs and lug nuts designed for high sheer strength and resistance to cross-thread. Metric grades are usually over 10.9 to 11.x or more and S.A.E. are usually over premium Grade 8 for studs AND the lug nuts for safety reasons. You don't want a wheel to fall off while driving or in traffic, especially a front wheel on the interstate as it puts you and the motoring public in great danger. A bouncing loose wheel in traffic can kill you or another motorist considering many off-road wheel & tire combinations weigh well over 100 Lbs.
Always re-torque after 500 to 1000 miles on new installs AND at normal tire rotation intervals thereafter.
Most adapter and spacer makers state on their website and in the paperwork that it is recommended to use thread locking compound such as Loctite to prevent the adapter or spacer lug nuts from coming loose.
Remember it's the clamping force that holds BOTH the wheel adapter AND wheel to the vehicle, along with help from the index hub if using centric type spacers or adapters. It is not easy to check the adapter lug nuts since one must remove the wheel to get to them for a check. Make sure they are re-checked for proper torque after 500 to 1000 miles and that the thread lock compound is thoroughly cleaned off any that were loose and then re-applied, then they are re-torqued if found to be loose. Any that were loose, inspect for galling or abrasion damage to parts from possible movement that could lead to premature future failures.
There are images all over the web of catastrophic failures due to improper torque or failure to keep adapters checked and properly tight. The results of a failure to comply with these guidelines set forth by the manufacturers of spacers can be deadly.
Be safe. Think smart and do the job properly from the start as if peoples lives depend on it.
Who knows, the life you save may be that of your own.......
RR