By Jim Kerr
Winter tires for winter; Summer Performance tires for summer; All Terrain tires for off-roading; All Season tires for everything? Do we need several different types of tires or can we just use one type all the time?
Tires are all that keeps our vehicle in contact with the ground. That may seem obvious, but drivers take their vehicles over many different types of surfaces – on and off-road, and tire manufacturers spend a lot in research developing the best tires for a wide variety of driving conditions.
For example, the tires used for land speed records at the Bonneville salt flats don’t need rain grooves in them or a lot of width. Formula One cars need wider tires for traction on corners, and Autocross racers need very soft sticky tires that will provide traction on a one-minute slalom run. How does this apply to your vehicle? Well, depending on your driving conditions, there are tires built specially for your vehicle too.
Most new passenger cars come with All Season (sometimes called Four Season) tires. They are a compromise but work reasonably well on dry pavement, wet pavement, a little mud and a little snow or ice. Long before All Season tires became popular, passenger vehicles used mainly summer or winter tires. Many drivers are going back to that routine again.
Summer tires are now often referred to as Summer Performance tires. They provide the best traction on warm, dry pavement and many work fairly well in the rain. Put them on ice or snow and all you will do is spin the tires. You will find performance tires on higher priced sports cars, but these tires do generally cost more and wear out faster, partly due to the stickier rubber compounds and the way they are driven.
Most drivers stay with All Season tires for the summer time. Even though they don’t provide the ultimate traction on dry pavement, they are good, plus they will handle some mud and ice and snow as well. They are really an all purpose tire, pretty good in many situations but not excelling at any of them.
More and more drivers are switching to winter tires for that additional traction on ice and snow. You can tell a winter tire by the “mountain” symbol moulded into the sidewall, but just as with other tires, there are different types of winter tires. Some work better in deep snow; others work better on smooth slippery ice. Tire dealers have all the information about these tires and the conditions that they work best in in their catalogs, or you can find it online from the tire manufacturers. Regardless of the type of winter tire, all of them work better than an All Season tire when the roads get really slippery.
I often get questions about when to change from winter tires back to All Season or Summer tires – or do they have to at all? It is advisable to take off your winter tires when the roads become clear and you don’t think it will snow again. This timing varies across the country: spring storms can fool all of us! You can drive winter tires in the summer, but the penalties are excessive tire wear, more heat build-up in the tires and less precise handling. Winter tires get traction by two main methods. One is the rubber compound: it is designed to remain flexible at low temperatures so it can conform to the road surface. Operate this tire on a hot summer day and the rubber becomes very soft, wearing quickly. It isn’t unsafe as long as tire pressures are correct, but you can wear out a set of expensive tires in only a few thousand kilometres on the highway. The occasional trip around town won’t make much difference.
The other way winter tires get traction is by having hundreds of sipes in the tread blocks. These small cuts provide gripping edges on slippery surfaces but allow the tread blocks to squirm more during steering inputs. In the winter, the cold rubber is stiffer and the roads are slippery so the steering feels fairly normal. In the summer, the movement in the tread blocks will give the car’s steering a mushy feeling.
Trucks and off-road vehicles are another story when it comes to tires, especially when they are carrying loads, but I will have to leave that for another time. The most important thing to remember about tires: check the tire pressure regularly.