4-6 drop with 22's help

[bhump]

My newest addition to my family of Silverados has a 4-6 drop with 20X8.5 wheels and I just bought 245/45/20 for the front and used 275/45/20 out back and no rubs. I am thinking of trading off the 18's and tires from my Z71 in order to get some 22's for my 02 with the 4-6. The wheels I want to trade for are the T.I.S. TS07, it is a 22X9.5 with a +18 offset. Does anyone know what offset I need in order to keep from rubbing the fenders with 255/30/22 tires? I dont want to lose the 18's off of my Z just to turn around and resell the 22's.

[Thundare]

Well if your gonna put bigger tires on a Truck, you will probably need a small lift on it. 2-3 INCH should do it