Quote:
Originally Posted by Nikolas
Actually Orb my understanding of basic physics is pretty well based in my education - I am a licensed architect. That aside, I guess I missed the boat on how resistance will not have an impact on traction.
What you are not seeing is that snow can produce a load on the object that is passing through it. This load can vary based upon the water content of the snow. This is why it is very easy to drive through very light snow and then with the exact same car driving through heavy wet snow - not so easy. Everything you are stating above is assuming a static situation where the traction is based upon the contact patch only. In fresh snow you are dealing with more than the contact patch.
If you think that resitance has nothing to do with traction, try driving your car across a frozen lake at speed with a 40 mph cross wind. I have done this in Maine. Trust me that force has a lot more to do with your traction than you realize.
If you read my post you will see that I agree with the concept that wider tires in packed snow and ice do work better. In deep snow, you are 100% incorrect. As I have stated I see this every year and have tried many different setups. I actuall go for a wider winter setup now because most of the time I am driving on packed snow and ice. If it were always fresh snow, a) I would have narrow tires & b) I would be one happy mofo during ski season.
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I understand the water content in the snow and the other variable as well. The assumption you’re making is the tire is a ridged structure. The tire acts as a spring on the component forces you are talking about so the energy is conserved. Now you have to consider the width vs depth frontal area were the snow would make normal contact for a narrow or wider contact….which is the greater evil. The assumption of saying there is multiple contact patches would not be a good one at all!! We will see some affect to the normal force to a very small degree. You have to realize tire friction is really the driving factor not the small details you’re pointing out in slight changes in normal force.
I’m not assuming the problem is static. I’m looking at this from dynamic point of view. This is not a sliding friction problem. The problem turns into a time step free body diagram. We can assume the time frame would be 1^-6 seconds. Computationally, we can solve this problem at this time step with variable transient conditions so it is dynamic. We should be clear on this.
The cross wind effect traction as it an external force but doesn’t really have much to do with narrow tires have better traction in snow. We are getting off topic.
I am sure you tiring to point out certain vehicle dynamics that would be unfavourable with a wide tire in deep snow. In that case I wouldn’t disagree but not in regards with traction.
Orb