i own a 2016 tahoe z71 with a leveling kit and with tires 285/65/R18 on factory rims now i want to install a 1 inch wheel spacer but they told me i have to trim the hub bolts and i want to install a wheel spacer that not more than 2 inchs and without bolt trimming
This depends on your wheels. Take one off and look at the back. Are there divots or voids in between the lug holes? On most stock wheels there are. If so, measure how deep they are. Then measure the length of the stud from the brake rotor to the tip. The spacer will need to be thicker than the length of the stud minus the depth of the divot.
Example:
I run a stock 18" wheel that has 3/4" divots in the back. My lug studs are 1-3/4" long. I could run a 1" spacer without trimming.
Notes:
I deem it wise to leave a little wiggle room, so I would run at least 1-1/4.
At least (I think a little more than) 1/4" of your lug studs are just the rounded tip. You can trim that off without losing any thread.