18s are fine as long as you buy what has been proven to work. you are not the first to buy stuff from custom offsets and then end up having problems. if anything, you should go straight to the manufacture and buy direct instead of going through a 3rd party that obviously has no idea of the fitments of what they are selling.
my thread details the wheel and tires used, methods, and why:
In this thread, I will be detailing the info regarding the tire choice, suspension choice, and trimming needed. Note: My procedure involves irreversible modification to the truck, so consult a professional of your choice and proceed at your own risk. This thread is to SHARE HOW I DID mine and...
5thgenrams.com