double the price of regulars, and not DOT legal in the US, I believe our Canadian brethren they are legal for.
Used them off road in the us logging. Except they were 1/2 links turned upside down and welded to the cross rail.
Use, those ^^ are generally intended for off-road use. They work well to grab tree roots and buried rocks for traction assistance on log roads, in wet or icy conditions. Even necessary sometimes in extreme angle climbs on dry, dirt conditions when there are buried things to grab on to.
Not sure about Colarado? In WA it's 4 for tractor (each outer drive tire) and one outer tandem tire (drag chain).Oregon is the same Except 2 chains (1 on each side of trailer)
I used to live in Portland and would loathe driving my car on the highway after it snowed because of all the pebbles flying everywhere. I would literally stay off the freeway for a week until all the pebbles got washed over to the shoulder. Used to piss me off.