Factory 17″ setup

Factory H2 wheels are 17×8.5” , ET+18, and Backspace 5.5” the standard tires are 315/70/17 which is about 34.4” overall diameter.

You can also jump to 37” on factory height, with the same wheels, to a 37×12.5 tire. If you notice any rubbing on tight corners, you can probably crank the factory torsion keys to add a bit of lift.

Aftermarket 17-18 setups

One measurement to consider ALWAYS is Backspace. Ignore Offset, when it comes to best fitment. Factory backspace is 5.5″, so any wheel with 5.5″ or lower up to 4.5″ maybe 4.25″ (probably on a lifted).

If you’re going with 9″ wide wheels on 17s or 18s with factory height and 315/70s, you’ll then find many brand wheels/types with different offsets ranging from +12 to -12. (for reference, see table below). Anyways most if not all 8-lug (8×165.1mm) wheels for Hummers have the Offset & backspacing done for you. The guide is a reference if you’re thinking on adding spacers.

*Quick note: Spacers reduce Backspace . e.g. adding a 1″ Spacer with a current 5″ Backspace, will give you a final 4″ backspace (pushing the tires further out).

Spacers also subtract Offset, so a1″ (25mm) spacer, on a ET 0 (offset) wheel will result in ET -25, but wouldn’t that then increase Backspace too? See it gets confusing if you do the calculations with Offset, which isn’t important. Always factor Backspace! here’s a good tool for testing (Calculator)

Depending on your setup, suspension components, fenders etc.. The more you push out, the more risk of hitting fenders and added load on suspensions. Too much negative offset, and inner tires/ wheels will hit suspension components, brakes etc.. Here’s where that graph below can help you calculate.

I’m on stock height, and went with 17×9 Black Rhino Primm wheels with ET 0 & 5″ backspace. That pushes my tires out by 24+mm , about 1″ further out.

Aftermarket 20 setups

You can run 20×9 or 10″ on stock height, as long as you stick with an overall tire diameter of 35-37″. Those would either be 325/60/20 for 35″ or 37×13.5 (Calculator) going for larger wheels, just requires you to recalculate height clearance, overall tire diameter, and backspace size.

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