Hi, I don't want to be a pain, but would you mind sending me a pic of your truck now? I can't seem to find any pics with the 1.25" leveling kit, plus those new tires you got on. I go in for an oil change in the next week or so and was thinking of asking the dealer to install the leveling kit. Did you install yours or have someone install it for you?
If you do end up putting the 265/70/17 tires on, can you please send a pic and comment on how your truck rides after install please? I am wanting to do the same thing when my tires start to wear down. I have the 265/65/17 and want a little bit more tire size without adding a leveling kit and such. From reading everything on here, it sounds like the 265/70/17 should fit in with no rubbing, but I have read conflicting stories about it.
As far as the warranty question you have, why not just call your dealer and ask if it will void the warranty?