285s on 18"????

[jtcain02]

Just bought a 2017 Silverado with RC 2" blocks in the front and some kind of 1" block in the back.  Dealership couldn't tell me what kind it was.  Anyway, it has the Goodyear Fortitude 265/65/18 on it now which shows a 31.5"x10.7" tire.  At full lock, there is barely enough room between the inside of the tire and the UCA for me to fit my finger.  Apprarently the individual that owned it before me had larger tires on it as well because you can see where they rubbed the UCA.  My question is, how are you all running 285s if there is barely enough room for the 265? I even see where some are running up to a 305 without rubbing. Am I missing something??? I was going to try the 295/65 Duratracs but there is no way I have a full inch there to play with. I'm wanting to go with the 285/65 or 285/70, but it really looks that would rub...