I work at a dealer ship and I just installed a 6" Skyjacker lift on a 2007 Chevy 3/4 HD. Lift turned out fine but the tire the customer picked didnt work so well. He got some 18X9 with a 4.5 BS and a set of Toyo Open Countrys 325/65/18. Needless to say it has some major clearance issues . Skyjacker suggests a 4" BS on 16" Rims and a set of 315/75/16. The customer wants to stay with 18" Wheels, what tire size if any could we go with to prevent from haveing to clearance so much of the Fender and Bumper. If there isnt a tire for that 18" what other wheel/tire combo would work. Thanks for the help guys.
Shawn

The difference in the two tires you mention is less then a half inch in width. Height wise they are about the same. Your issue may have been just the backspacing. Here is a pretty good tire calculator so you can play with different sizes. The width of the rim will also have some effect on how they fit.

http://www.miata.net/garage/tirecalc.html