Originally Posted by JCL

Brandon:

You continue to confuse the various types of friction.

Older snow tires, and snowmobile belts for that matter (since you mention them) work in a particular way. They work by having a deep lug around the shoulder of the tire that digs in. As long as the lug can dig in (whether it is on the edge of an old-tech snow tire) or across the belt of a snowmobile, it will provide traction. This is where the old maxim about using narrower tires in snow comes from. Raising the inflation pressure on this design of tire will provide a cleaner should edge that grips better.

Modern winter tires have sipes all across the tread. They don't dig in in the same manner, rather all of the sipes provide traction. This is also the concept behind ice tires. These tires are not designed to sink in, but rather stay on top. And they work very well. Years back, there was no effective 20" automotive winter tire, they simply didn't exist. Today, we have performance winter tires in sizes such as the X5 sport package uses, and they in fact work better than the old tech snow tires. Overinflating these tires will reduce their winter performance.

If you are so convinced that narrower is better, without considering tread compounds and tread patterns, put an old narrow snow tire up against a modern performance winter tire and see which works better. You may be surprised.