SJx408

Looking at getting a set of 18x10 Forgestar F14's for my 96 Z. Car is lowered 1.8 inches or so and I'm prepared for mods like fender rolling or the use of a BFH to massage my fender wells. Adj. PHB and LCA's with relos are on the way. In the future I plan on running a BBK a la C6 or c6Z06 style or any other option so long as they are larger and stop better than the tiny stock brakes it has now. Reason I mention all this is because it is crucial for getting the correct offset. Plan is to be able to rotate these for mainly road course and auto x days with occasional street use so a square setup is what I'm choosing again in 18x10. However, I'm having trouble with the offset, some dealers I've spoke to suggested something along the lines of +38 to +42. I just figured I would ask around and see what other people are running and hopefully find a couple users with the same wheels and see what sizes they run. Tire choice I will be 275/35R18 Toyo R888's, just throwing that out there to see if it seems like a reasonable size for these wheels. Thanks in advance for any replies. I'd really like to pull the trigger on these soon.