Further to above, do not take 89. We came back that way last spring, very slow twisty up and down road. No way would want to be on it in winter. Will be much quicker and safer for u to go #2 south of Calgary to Coutts. There are several passes on I15 which could require chains if conditions were bad but we just would just wait it out if that bad. If you have driven Rogers pass you will find the passes on I15 nothing as they are not as steep. Hope this helps you and have a great trip. We are addicted to going south now!