Tire size with 1.5 leveling and1.75 adapters

I have a 09 titan se it's got the stock rims and right now cooper at3s 265 70 18. I have a 1.5 inch leveling kit along with 1.75 inch wheel adapters. It's about time for some new tires. As of right now with the wheel full turned I have maybe a half inch of clearance in the inner back of the wheel well. I really would like a wider tire, even with the adapters I'm still not flush with the flares I don't think. I know in can do the pinch weld mod, not sure how much space I can gain from it though. I really want to get the terra grappler 305 65 18 but don't want to spend all the money just to find out they don't fit. Rims or lifting isn't an option right now as just bought a house and am remodeling it and wife would kill me. Thanks alot