Cars and trucks these days come with larger rims and tires than ever before. Wider tires give the vehicle a larger contact patch on the road, which in normal conditions means better grip, and therefore better performance. Unfortunately, as with any great advancement, there is usually some sort of down side. In Canada we benefit from the increased performance from larger rims and tires for 3 seasons of the year, but this set-up works against us in the winter months. Think of it like this.
If you have to trek across a field of snow, are you going to opt for your runners, or snowshoes? Winter testing is difficult. Surface condition is critical and the surface must constantly be refreshed. Temperature is also a huge factor. Tires must be at ambient temperature for at least 12 hours, so tires are mounted the night before and left outside. Advertisement Acceleration tests are the most repeatable. Testers usually do rolling tests from 5 mph because they are more repeatable than standing starts.
Usually accelerating up to about 25 mph is enough. Ice testing is easier to control than snow testing because the surface is more stable and requires less grooming. Lap times are important, but subjective feel is usually the most significant factor. The problem for the testers is that max grip and the best lap times are generated at higher slip angles than most consumers are capable of controlling. So do you drive like a typical consumer emphasizing subjective feel or drive for the best possible performance?
Subjective feel usually wins out. Advertisement Testing usually focuses on tread patterns and compounds. Generally new tires use standard constructions since there are few benefits to special ones for winter use.
What are manufacturers working on? Compounds with extended temperature ranges and more porosity; more exotic sipes 3-D sipes are an important advance ; directionality; asymmetric tires with the outside edge designed for non-snow conditions and higher cornering forces.
Cost is a common, and significant, consumer objection. The additional expense is partially offset by extending the combined years of service they get from both sets of tires. Advertisement In addition, AWD and 4WD vehicles have become very popular in the snowbelt region of North America, largely because their drivetrain systems make winter driving easier.
ABS helps prevent locking tires and skidding and can assist in maintaining steering control and directional stability. Traction control helps prevent spinning tires and maintains directional stability. ESC helps correct oversteer or understeer.
Advertisement Few drivers understand that all-season tires are a compromise intended to provide acceptable traits under a wide variety of conditions. Ice skates or crampons, however, allow people to move relatively freely.
In deep snow, on the other hand, skates and crampons serve little purpose. Yet skies and snow boots will prevent you from sinking into the snow, allowing you to move around on the surface. As you can see, the key to efficient movement on winter surfaces is to exert the right amount of pressure on the ground. This directly depends on the size of the contact area that exists between the person and the surface.
For driving on ice , very high pressure is required and thus needs a minimal contact area while deep snow requires a minimum amount of pressure spread over the maximal possible contact area. In short, the unit pressure on the ground should be your main factor for choosing tyres. For ice, the pressure should be as great as possible, while deep snow requires as little as possible. As stated earlier, winter often has the biggest variety of road conditions, compared to the other seasons. On a given winter road, you may have to deal with the following surfaces:.
In winter, you may also encounter layered surfaces. For example, a lower layer of ice or hard snow which offers the worst possible grip might be underneath an upper layer of dry or wet loose snow providing high resistance to movement. This can include:. All of these need to be considered, as the conditions you expect to encounter the most can influence your choice of winter car tyre. When driving, the level of grip is also affected by the unevenness of snowy and icy surfaces, such as icy ridges, frozen ruts or bumps, as well as potholes formed by both snow and ice.
Of course, it is next to impossible to prepare for the exact road conditions on any given journey. It is impractical to change your winter tyres this frequently.
For most drivers, it is better to have winter tyres that cater to the most common and frequent conditions in the areas they drive. Generally speaking, it can be assumed that wider tyres will be better on a soft surface, as they prevent the vehicle from sinking. In the case of hard surfaces, narrow tyres can be expected to offer superior performance, as they increase the pressure exerted on the surface, improving grip as a result.
In the very toughest road conditions, it is recommended to always use winter tyres designed for extreme road conditions. These have a width of two, or even three, sizes smaller than your summer tyres. These tyres offer enough traction to get you through most cases without the need for snow chains. Here are some things to consider when deciding what kind of tires you should purchase for your car:.
Car weight — For some vehicles, buying a skinnier tire is not realistic because the weight of the vehicle will put too much pressure on the tire.
If you were to mount a thin tire on a car that was too heavy, you would run the risk of the tire exploding while you were on the road. However, if you mount tires that are too wide on a vehicle that is light, you may experience wheelspin, which can damage other internal systems in your car.
So make sure you purchase the appropriate tires based on the weight of your vehicle.
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