Got it, you if you had to chain up it would likely be on I-25 not I-70 in the mountains correct?
If so I would say it's extremely rare they would call a Code 16 on I-25. To be honest I'm a Colorado native and have never owned chains. Just good tires and 4WD and I am just fine.
But, that stretch from Colorado Springs to Denver (and vice versa) is madness. There are people who are just flat crazy along that stretch (I call it Road Rage Central) and will be doing 80 mph in a complete white out OR you have the person doing 10 mph in the far left lane. I avoid that stretch of highway at all costs and there are some alternate routes to do so.
You probably already know this but I-25 is a CDOT maintained highway and they use Mag Chloride on it. If you do have to drive on it during a snow storm, get your vehicle to a self serve car wash ASAP the next day and spray it off under and on top real good.
If you don't, it will eat your vehicle alive. I hate that crap.
Yeah. My wife and I are Colorado natives (Fort Collins and Broomfield). We are very familiar with that stretch and the chemicals they use for de-icing. Our problem really isn't in Colorado unless we go visit my aunt and uncle in Steamboat. Then chains are a must.
The OP was referring to SW Colorado around Durango. My parents lived in Cortez and Farmington for a while. So, I drove that area and up to Fort Collins for a good 4 years, and those roads can easily get closed down. I have actually been on Wolf Creek Pass when the gates were closed behind me. I didn't know until I made it down and the officer at the gate told me that no one was supposed to be up there. ...thanks for the advanced warning...
Our biggest problem now-a-days is the panhandle of Texas, Oklahoma, Kansas, and Northeast New Mexico (before I-25). Similar to the worst case scenario described earlier, on one trip we were North of Amarillo when a 65 degree day became a white-out snow storm with the highway being shut down at Dumas. I was able to traverse the opposite lanes of 287 after the Highway Patrol told us there was no one coming since it was closed. Myself and the Land Cruiser in front of us were the only ones to make it across the median and go the wrong way in the South bound lanes.
Last year we encountered enough snow and ice in and around Lubbock, TX to have most of the traffic sliding off the road. The biggest problem is that none of the surrounding states are as good as Colorado when clearing snow and ice from major roadways. I think Texas is actually the worst.
Are you guys just using chains on the rear wheels only?
At a minimum, they should be on the "drive" wheels. Even on our 4WD 4Runners, the drive wheels are considered the rear wheels. I carry chains for all 4 wheels.
I ski multiple days every winter in Colorado - have for 40 years - and I have never run into a chain requirement on I-70. That's not to say you won't run into it, but it's pretty rare for an actual chain law to be applied for passenger vehicles. As a previous poster said, if it gets that bad just park and wait it out, because you won't want to be on the road anyway.
The snow sock is a useful emergency thing to have in your vehicle. It's cheap, easy to put on, takes up little space, and is fairly effective on ice. From what I understand they are pretty much a one-time use item, as they wear very quickly. They also aren't all that effective on deep snow - for that you need good tread or real chains.
But honestly, CDOT does an awesome job of staying on top of the major roads in the mountains, and if you're willing to wait a few hours you won't need chains or snow socks unless you are traveling secondary roads.
To address another point, I don't think there's enough clearance to the upper ball joint to put chains on the front of a stock 4th or 5th gen 4runner. Unless you have wheel spacers or offset wheels chains are pretty much a rear-wheel only option, I think.
I believe the s-class clearance chains will fit without hitting the upper ball joint, but only if you are running stock size tires.
All of that being said, unless you "must" travel in those conditions, waiting a few hours is always the best plan of action.
