Lot's of owners have two sets of wheel & tires; One set for summer and one set for winter. Since you live in Colorado you guys see a lot more snowfall than most other areas. It probably wouldn't be a bad idea to have a dedicated winter wheel set-up with some Blizzaks.
As
@Stbentoak mentioned: Find the cheapest set of wheels that you know will fit and put the best snow tire on there you can! Or even better, cruise FB marketplace, eBay, and craiglist for lightly used wheels OEM or aftermarket.
I don’t think 18’s will clear…they might though. Seemed pretty tight w/ the 20’s on there. The big thing is the 28mm offset and the spoke shape to clear the caliper…check it, but it may be marginal.
I had wondered this as well. With the '21 + T1XX models having the larger 4-piston front calipers I'm not sure an 18" rim will fit. I believe that currently when you are building out a '21 + Tahoe/Yukon/Escalade the smallest diameter wheel you can get is a 20". Even building out an Yukon AT4 or Tahoe Z71 model they have standard 20" wheels.
That being said a the Sierra AT4 and Silverado Trail Boss model trucks have 18" wheels and they have the same front 4 piston brake set up as the SUV's. So if you're dead set on 18" wheels you could find some AT4 or Trail Boss take-offs and I'm sure they'd work. Out of curiosity I looked at the Chevrolet Silverado WT's (Work Trucks) and they come with 17" wheels. I wasn't able to confirm if the Silverado Work Trucks have the 4-piston front brakes as standard, but I would be very surprised if they didn't.
