I'm a professional semi/fuel hauler down in Denver
If 70 is bad enough that you need chains on your personal, you shouldn't even be on it. 70 goes from bad to impassible in a flash.
The state believe it or not, actually does a pretty decent job of keeping 70 open. For us drivers it's safer than shooting up 80 thru wyoming because 70 rarely shuts, they just put on chain laws.
If I were you, I wouldn't bother with chains because you have a good chance of causing damage to your vehicle when you drive to fast and break a chain link... That chain will beat the crap out of your car before you can even stop. Chains can also give you a false sense of security, you don't want that.
Just get a nice set (4) of winter tires. Don't bother with studs as they aren't very affective once you drive on dry pavement, and they can cause you to slide and wipe out on wet/rainy roads.
Get winter tires with some nice siping and drive smart.
Rumor has it we won't have a chance to go to fast this season anyways.... Looks like we're going to have pace cars leading us around at 55mph tops, around the tunnel.
My best advice, get a real car. A Yaris doesn't belong in the mountains during the winter.
"When I do good, I feel good; when I do bad, I feel bad. Thatís my religion." - Abraham Lincoln