I just recently put a 6 Zone lift kit in my 2009 Duramax and put on the recommended 20 wheels with 35x12.5 tires and they don't come close to rubbing. ...

I just recently put a 6" Zone lift kit in my 2009 Duramax and put on the recommended 20" wheels with 35x12.5 tires and they don't come close to rubbing. There's a guy selling some 37x11.50 and I'm wondering if they'll fit since they're narrower. From what I've read, the size limit is due to rubbing when turning, so maybe these could be alright? Anyone tried it?

hard to answer. What is the wheel width and offset?

literally the easiest way to do it would be crank the wheels until its as close to touching the cab as possible. Measure that and do a little simple math. You would need roughly a full inch of clearance now to go up to the 37x11.5 if my quick math is right.

This is what they have listed in the installation notes for wheels:

20 x 9 w/ 5.75" BS
17 x 9 w/ 5-5.5" BS
18 x 9 w/ 5-5.5" BS
16 x 8 w/ 4.5" BS

I've currently got 20x9's on with 35x12.5 tires. The torsion keys are barely torque'd up too. I wouldn't mind having to do a little trimming, but I'd hate to buy these guys and find out it's not going to happen.

I'll try your method though, as I haven't seen any confirmations this will work anywhere else. Thanks.

They are always conservative on sizes, Do you have aftermarket or stock 20 inch wheels? I see that you said they put on the recommended ones so I assume they are 20x9 with 5.75"BS I think that may still be a positive mm offset?

see if you can get that measurement like I mentioned. If you have 1" when measuring this gap chances are you can fit them with little to no trimming. Them being 11.5" wide help more than you know.