I have a 4/6 drop on my 08 ecsb and lookin at a set of 22's, i still have my fenders in the front, should i run a +15 offset or +30, im tryin to keep them from rubbin inner fender, and i dont wanna hit the outter fender

 

+30
also a narrower tire wont rub.

 

Aight thanks

 

I have a 22x9" with a +31 offset.
lowered 3/5 with fender liner still in. I do get a little rubbing when turning lock to lock, but not enough to damage anything. I also get a little rubbing on the top of the fender well when hitting large bumps, but again not too bad. I'm running a 305/40/22 tire, and I believe if I had something closer to factory size, with this offset, I'd never have any issues at all.
Theses are the wheels that I have:
22'' Chevy LTZ Texas Machined Wheels New Rims GMC Yukon Silverado | eBay