I recommend snow tires and carry chains but don't really plan on using them. I70 stays open most of the year, but it does close several times over a season too. Maybe 2-4 times on average due to a storm and avalanche danger. The other 20 or so closures is because some damn big rig that jack knifed. The fuel trucks seem to do it more than anyone forcing Haz-mat closures for hours.
Vail Pass also closes quite a bit, maybe more frequently than the Eisenhower tunnel. The amount of fill they used to build the pass on the West side allows the road to freeze over quicker than at other places.
For the record, I just use a FWD vehicle with snow tires. I do keep chains in the trunk and have yet to use them. In 22 years I have never put chains on my vehicle to get to the hill.