The truck has a 275/60/20 that a od of 33 and the 275/65/20 is a od of 34.1 that would only be half a inch on top and half inch on the bottom I've been reading that the 305/55/20 rub because of the width being 12.50 and the 275/65/20 is only 11 wide
It doesn't void your warranty..... No single mod you do to your truck can void your entire warranty. It's illegal for a dealership to even do that. Sure they might not warranty some front end parts that might fail prematurely because of the leveling kit (such as ball joints, bushings, etc) but that's just part of it. You gotta pay to play.
The warranty can only be voided if they can prove the mod (in this case a level kit) was the cause of the problem. So as I said, it doesn't necessarily void your entire suspension warranty either.
Before you reply back you should maybe do a quick search on the forum and see all the posts guys have written about mods and warranty. You will probably learn quite a bit about it and how the warranty act works.