I have a 2003 silverado z71 with stock 2010 wheels with 265/65r18 tires. I am planning on getting a 2-2.5" leveling kit, whats the biggest tire I could fit without any modifications? a 285/70r18 or a 285/75r18?? also what would be the best/cheapest leveling kit that would work. Any advice is appreciated, thanks.