With winter fast approaching I thought this would be a great topic to address with my first informational post.
How do winter tires work?
Here are a few pictures to illustrate the mechanics involved in winter traction.
If you look closely at a road surface, it's not as smooth as you might think. The road surface is represented by the model in this picture.
With the high grip rubber compound used in your summer performance tires, the contact area conforms to the irregular surface of the road.
That amount of contact can generate a tremendous amount of traction in the summer time 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 all three parts are vital to generating good traction
Tread design is the first piece to the puzzle.
This picture shows a winter tire tread design which utilizes a large number of sipes.
When the road is covered with snow, the tire is no longer able to conform to the surface.
The siping allows the tread elements to flex under stress and create aggressive "biting edges" when braking, cornering or accelerating.
Tread depth is the second piece to the puzzle.
While deep snow and ice-covered roads are two of the most challenging conditions North American drivers will face, tire developments during the last decade have noticeably advanced wintertime mobility. The technological revolution of dedicated winter tires for drivers in the snowbelt, and the continuing evolution of all-season tires for drivers living on its periphery, offer more grip in snow and on ice than ever before.
However, the basics of delivering traction and handling on snow and ice remain unchanged. Tires must combine three fundamental features to deliver good winter time performance, including an appropriate tread design, pliable tread compound and sufficient tread depth. If any one of these fundamental features is absent, the other two, regardless of their ability, cannot deliver the desired results! Since engineers can develop cutting-edge tread designs and chemists can develop advanced rubber compounds, it is often the remaining tread depth that is the variable in determining wintertime performance.
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 between the tire's grooves to show when the tire's tread has worn down to the minimum legal limit of 2/32 inch.
However, in spite of the legal minimums, Tire Rack recommends that drivers expecting to experience wet conditions consider replacing their tires when they reach 4/32" of remaining tread depth. Tire Rack's tests have shown that shallow treads reduce wet braking traction and increase stopping distances
Tire Rack also recommends 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 winter 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.
[FONT=Verdana][SIZE=2]The third and final part of the puzzle is the rubber compound used. Rubber compounds vary widely from manufacturer to manufacturer but, the task is the same so, you will see 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 and other materials which add more bite on ice.
Selecting the proper style of winter tire is also very important.
There are basically three different types of winter tires
#1.) Performance Winter
Performance winter tires are designed for customers willing to trade a little snow and ice traction for more stable, responsive handling in the dry conditions.
Meeting severe snow service requirements and branded with the "Snowflake-on-the-Mountain" symbol, these low profile, H or V speed rated tires are designed to suit winter driving on European highways. They are available in many of the low profile sizes used on larger wheel diameters. Due to their unique designs, performance winter tires must be mounted on the vehicle as a set of four.
#2.) Studless Ice and Snow
Studless ice and snow tires are designed to offer the best available snow and ice traction, sacrificing some dry performance and treadlife. They meey severe snow service requirements and are branded with the "Snowflake-on-the-Mountain" symbol. These Q, R or T speed rated tires feature the latest in tread compound technology to provide winter traction without the inconvenience of tire studs. They trade a little handling for excellent ice and snow traction. Due to their unique tread compounds these tires must be installed in sets of four.
#3.)Studdable Winter
These meet severe snow service requirements and branded with the "Snowflake-on-the-Mountain" symbol, these tires feature traditional snow tire tread compounds and studdable tread designs for good snow and ice traction. Due to their unique designs, these tires must be used in sets of four. Use of studded tires is prohibited or restricted in certain states or provinces. Check with local authorities to confirm legality.
But Do I Really Need Winter Tires?
The primary concern that our customers express is that they don't want to get "stuck" in the snow (or in the ditch) during the winter.
Cities like Atlantic City, Nashville and Seattle are located at the extreme edges of the snow belt. For most drivers in an area like this, a good set of all-seasons will probably work for the winter months.
We all know that tires are a compromise. One tire can't be the fastest on the track, most controllable in the snow, and longest wearing. The Ultra High Performance tire that grips the track with tread temperatures of 200° is incompetent as its tread compound becomes like "hard plastic" at below 32°. Today's 80,000-mile tires require tread designs and compounds that maximize long, even wear... not winter traction. And while many of today's all-season tires (Original Equipment, touring and performance) address some of these issues, they still emphasize longer wear, a quiet ride or greater dry performance over winter traction.
Only winter tires are designed to excel in the colder temperatures, slush, snow and ice that many parts of the country experience for three or more months a year.
It's also important to note that the recent advancements in electronic driver aids, such as ABS and traction control, don't provide more traction. They only help prevent drivers from over braking or overpowering the available traction of their tires. The only thing the driver can do to increase traction is to install better tires.
With all of the different sizes, fitments and requirements for each car and driver, I can't list all the different models and options.
As in the past, there are 'general use' recommended packages for each model car to be found at
http://www.tirerack.com/a.jsp?a=DG2&url=/winter/index.jsp.
If you would like to discuss other options for
your specific needs please don't hesitate to give me a call at
800-428-8355 ext. 283 or drop me an
BJ@tirerack.com.
You can also post in this thread for recommendations specific to your needs. This will allow other users to see the same recommendations and will make more useful information available to the group.
year:
make:
model:
location:
tires only or winter package:
I will respond directly to your post