Winter tires ... how do they work

Wednesday, August 5, 2009 by Luke Pavlick
There's more to tires than black, round and hold air. This post should help you understand the mechanics of winter tires






When you look closely at any road surface it is really not that smooth as represented by the model in this picture











The engineers who design those high grip summer performance tires we love so much, also know this and use it to their advantage.

They incorporate high grip rubber compounds that  conform to the irregular surface of the road. That much surface contact can generate  tremendous amounts of traction for cornering, accelerating and braking.

but, what if the road in snow covered?


That brings us to the question, what makes a tire a good winter tire? The answer is a three part puzzle and without all three parts traction will be compromised.


  • let's look at the first part of the puzzle; tread design




this winter tire utilizes a large number of sipes which is a typical feature found in winter tire tread designs










when the road gets snow covered the tire is no longer able to conform to the surface.

The siping in the tread design allows the tread elements to flex under stress which creates aggressive "biting edges" when braking, cornering or accelerating


  • part two of our three piece traction puzzle is tread depth

In most parts of the world, tires are considered to be legally worn out when they reach 2/32" (approximately 1.6mm) of remaining tread depth. U.S. law requires tires to have easy-to-see Tread Wear Indicator bars running from one side of their tread design to the other when the tire's tread has worn down to the minimum legal limit of 2/32 inch.
 
We here at The Tire Rack recommend that drivers expecting to encounter snow-covered roads consider replacing their tires when they reach approximately 6/32" of remaining tread depth to maintain good mobility. Tires need more tread depth in wintry conditions to compress snow in their grooves and release it as they roll. If there isn't sufficient tread depth, the "bites" of snow that can be processed on each tire revolution will be reduced to "nibbles," and the vehicle's traction and mobility in snow will be reduced.



 
 
  • The third and final part of the puzzle is the rubber compound

Rubber compounds vary widely from manufacturer to manufacturer but, the task is the same so, you will see some similarities between the products. They all typically use compounds which utilize materials designed to remain flexible at cold temps in addition to traction enhancements from silica, fibers and other materials which add more bite on ice.


My name is Luke Pavlick and I am a Car Guy
 

Comments on Winter tires ... how do they work

Wednesday, October 21, 2009 by jeff:
great informative post. now what snow tires do you recommend for a RX8 2009 which would maximize control in slush and light snow in the Washington DC area?
Thursday, November 12, 2009 by Luke:
With a sporty car like you RX8 and considering your area the Dunlop Winter Sport 3D's would be a great choice as it is very versatile and offers good handling characteristics
Thursday, September 9, 2010 by Wyll:
How important is it to have all four winter tire as compared to just buying two? I drive an fwd 2004 Dodge SRT4 and only change to front wheels in the summer. The rest of the year I use the stock tires. This year I am planning on buying winter tires for the first time.
Monday, September 13, 2010 by Luke:
Winter tires should always be used in sets of four. If you were to put winter tires on only the front or rear of your vehicle, you will have more traction on the end of the car with the winter tires. The difference in ice and snow grip between Winter tires and all-season or performance tires is very significant and could easily cause you to lose control of your vehicle. My advice ... get all four and take the drama out of winter driving. Thanks for reading my blog!!!

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