I've always called the ones you describe adapters as they have their own lugs, I guess as long as they don't modify the lug pattern they are spacers.

When looking for some for my truck the thinnest I could find was around 1.5" with lugs so I tried the spacers without lugs but once I tried them the lugs are just to short.

I was looking to space my wheels out around 1/2" for a better looking stance but have not done anything to date. I was thinking about changing the lugs to longer ones but have not decided what direction to go just yet.

Neal

 

There has been a lot of discussion over the years on spacers. The thought was to not change the length of the studs. That length is set by manufacturers for a reason, tensile strength, etc. The reason correct spacers with their own lugs or adapters as you called them only go so short is because they have to hide for a lack of better terms the factory studs and lugs. I wanted mine pushed out quite a bit due to the offroad flares I installed which was why I went with aftermarket wheels. That is the safest bet to push your wheels out, changing backspacing/offset with new wheels. Obviously much more expensive but also safer in my book.