The 225 is just a wee-bit stretched for my liking on the 8.5" fronts, but if you go any wider, you must drop the aspect ratio or else you will hit the suspension bolt. The problem with doing that, is load ratings.

I would love to go to a 235/35/18 but those are all SL rated tires... we had XL from the factory and I don't want to risk a blowout at 130+mph...

On the rears, you will need to upgrade to at least a 265, as the 255 on the factory 9" rim is at the limit of being stretched already. I would recommend at least a 275/35/19 to protect the rim of these beauties