Wheel spacers.
Wheel spacers will work, BUT you HAVE to be careful. If yu get spacers that are too wide, you wont have enough bolt for the lugnut to hold on to. I've never had it happen, but I'm sure having your wheel come of on the interstate would be bad.
I have a set of spaver, but they are only 3/16" wide. They are to keep my front tire from rubbing the sway bar when turning. They are thin enought to have enough thread left.
I have also seen spacers that bolt onto the hubs and then have a new set of bolts to attach the wheel. These would probably work, but I'n not sure about extra stress on the suspension, or steering geometry changes. Ask a mechanic. They might know. Hope this helps.