Widest tie on a 18 x 10.5 rim?
 

What's the widest Nitto tire you can fit for the rear? 295/35,315/35?

well..u can fit a 315/35 on a 17x10.5 inch tire...so prolly a 315/30x18

the only downfall of 18" tires is that they are mad $$$$$$$$$$$$$$$$$$$$

Can anyone tell me if a 315/30/18 Nitto would work with no clearance issues?

315 fits no problem.