Did your lift also level your truck? If not, you could pick up a leveling kit, and get up to another 2.5 inches that way..... If it did, an add a leaf in the back in combination might help. But, since you are rubbing on steel..... you may need to get different rims.

 

Do you know the backspacing on the rims you have, and do you have any pictures or can you take a picture of exactly were it is rubbing

It sounds like its more of a rim issue and wheel spacers might help if the bs is too much

 

Wouldn't spacers just make the problem worse? Sounds like his tires already stick out too far.....