I recently got a pair of 1.5" wheel adapters for my truck for an aggressive stance and so my tires don't rub. When I put the spacer on the lugs stick out of the spacer. Can I leave these lugs sticking out about not even an 1/8" and rest the wheels on the if they rest flush against the studs with no wobble?

 

Look at the back side of the wheel. Many wheels have a hollow area on the hub between the holes. If yours are flat, you'll need to cut or grind down the length of the studs. I've used adapter/spacers on a couple of vehicles, currently have a set on my Jeep. I use nothing but model specific billet aluminum hub-centric adapters. The center hole fits the vehicle axle, and they have a wheel hub mounting flange. That makes them stronger and safer than the cheaper universal ones that only rely on the lug nuts to keep it locked on center. Also, be sure to put red Loctite on the lug nuts that are holding the adapters to the axle.