How many snow tire chains are needed for snow and ice on a 4 wheel drive SUV (4x4)? If only one set

As soon as the first snow hits the roads my e-mail box fills up with questions from SUV owners like: "I plan on buying a pair of snow tire chains for an upcoming ski trip - is it better to mount the snow chains on front or rear tires of my 4x4?"

Traction is needed for acceleration and negative acceleration (braking). And of course for steering. If the ground does not provide enough traction, snow tire chains are recommended to increase traction - however, if you use a set of chains only on one axle you are essentially re-converting your 4WD/AWD into a 2WD vehicle - a 4 brake vehicle into a 2 brake vehicle. Would you buy a car that has only two brakes?????

Also: For maximum braking and shortest stopping distances snow tire chains are mandatory on all four wheels. With a snow tire chain set on only one axle the stopping distance would be twice as long. Imagine the Range Rover (top image) with chains only on the tires of one axle.

Why spend a premium to own a modern AWD or 4WD SUV to have the safety of a sophisticated 4WD/AWD system and then save $200 for a second pair of snow chains and throw the advantages of 4WD/AWD out of the window?

Mercedes-Benz for example, strongly recommends the use of two pair of chains - and it would be unwise not to follow their advice.

If only the tires of one axle would be fitted with chains the other pair of tires would frequently try to slip - 4ETS traction control would step in and prevent the chainless tires from slipping (and they will try to slip since they don't have chains) - so far so good - after many 4ETS interventions in a short period of time the computer would shut down 4ETS (a built in safety to keep the brakes from overheating) - without 4ETS traction control intervention power would go only to the tires without traction (the ones without chains) - they will be spinning & since spinning tires will not move your car - you'll be stuck!
Here is more about where to put chains if you have only one pair.

Unfortunately you still have to get down on your knees to mount tire chains - a small price if you consider, how much safety you gain!

How many snow tire chains are needed on a 4x4, 4 wheel drive SUV?