lock the hubs

"Lock the hubs" is motorist jargon for engaging four wheel drive. Older trucks & SUVs as well as some newer base model vehicles are equipped with manual locking hubs rather than automatic on the fly 4×4. Such vehicles require driver to park, shift transfer case in the cab to 4-HI or 4-LO AND go outside to turn dail on front wheel hubs to "LOCK" before proceeding. Some folks driving in irregular winter conditions will lock the hubs but stay in two wheel drive until they need 4×4. Running locked hubs with 2 wheel drive otherwise increases front tire wear.

Tyler: Hey Tom, I'm planning on going skiing today, how are the roads going up to the mountain?
Tom: Roads are a bit snowy & icy in places but if you lock the hubs, you should be fine!