I have a set (4)for my AT4 that I downsized from previous trucks with the V Bar. I haven't had to use them in the last 20 years but used to go sledding to BC and their roads could get occasional heavy snow or ice in the passes.
I'm not sure that you will need them in Colorado unless someone from the area recommends or requires them. A set of two should be enough unless you are pulling a big and heavy camper??
If you haven't used chains before you may want to put them on at home (practise) and make sure that if needed they are tight enough that they don't contact the fenders etc. when spinning.
Interesting. It's got specific tire sizes listed to not use chains. Are any of the factory sizes not listed here? My 20s definitely are listed in the do not use chains list. I did not recall this.
That is why I said that you should try them at home on a nice dry pad etc. start at the rear and tighten them properly so that the cross links don't flap or the chain is so loose that it moves from outside to inside or vice versa. Once you have the chain on rotate the tire while on a jack to check for clearance at the front especially. If the chain clears with some space you should be okay to use it at low speed to get out of mud hole or snow. You can do the same at the front if you are concerned about the clearance of either the front or the back you can make that decision at home not while laying in the mud or snow.
Yes I read the disclaimer in the manual when I bought the truck; my truck is the 22R 1500 CC AT4.
Those with taller than stock tires will be a non starter because there isn't sufficient clearance.
I have my 275/60R20 summer tires on now that are slightly taller and there is enough room on the rear axle, the front axle has 3" to the front of the fender and less towards the mud flap so it would be tight and you would have to use the chains at very low speed probably low range. Your vehicle so make your own decision.
On my stock 275/60/20s in the rear the closest thing is the leaf spring to the interior not front to back stuff. Be sure to check all sides and not on a Jack but down and loaded for clearance.