Tires can make all the difference in the world. And chains make even more/better for snow/ice. Then there is the effects of the car/truck power/torque to drive wheel weight and the driver, too.
I've been places in a Chevy Vega (2.3, 1 barrel carb, 4 spd. manual, with chains on it) that 4WD trucks had to be 4WD to go.
I've been places in a Pontiac Astre (Pontiac Vega with a 2.3, 2 barrel carb, 5 spd. with a good set of Sears XST snow tires) that all manner of trucks, busses, cars, etc. couldn't go. Came across Rt. 60 in WV one night in a heck of a snow storm. Got home, father-in-law wanted to know how we got home. I told him Rt. 60, like always. He told me the WV State Police had Rt. 60 closed due to the snow/ice/accidents, etc. I told him they must have closed in from the phone in their barracks because we didn't see a single Trooper during our trip. Lots of cars/trucks and a Greyhound bus up against the guard rails, in the ditch, sitting in the road unable to get farther, but no State Troopers.
I drove around in the snow for with 2WD cars (1 wheel most of the time as none had posi traction rears) for 12 years before I ever got a 4WD SUV. Now I've got four either 4WD or AWD vehicles and three of them have never been in the snow with me driving them. Just the old truck that still goes home in the winter time snow/ice and salt.
My dad lived/drove 2WD vehicle in MI, ND, IL, WV winters for 20 years before he got a 4WD truck. After that first one, he had several more. I guess he figured moving the lever was quicker, easier than putting on a set of chains.
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