Behold: The NorCal mod for Chevy trucks. Shown is on a GMT900, but works on 800s too.
https://www.duramaxforum.com/forum/nor-cal-truck/69677-2007-5-2014-nbs-hd-large-fender-mod-step-step-pics.htm
The 'Burban runs (and clears) 295/65-18s, which is a 33" tires, with a 1.5" lift in front, and one in back.
The mod took one hour on the first side, and about 15 minutes on the second side.
BTW, talking about a tires width (265 or 285) without knowing its aspect ratio and wheel diameter, or overall diameter, is a waste of time.
Happy cutting and modding to all Chevy owners who check out that link...
:-)