All-Season Versus Winter Tires

A couple of generations ago, almost anyone in Indiana didn’t think twice about having a set of “snow tires” stored in the corner of the garage, waiting until October or November to be swapped with the regular tires until springtime. This is less common now, but should it be? Alderman Automotive explains. 

Two issues diminished the use of snow tires. First, people started driving front-wheel-drive cars, which enhanced traction by having the driving wheels under the weight of the engine. With the SUV revolution came all-wheel-drive vehicles that improved winter driving confidence by applying forward-motion force to all points of contact. The second change was that starting with the Goodyear Tiempo in 1977, “all-season” tires started being fitted as original equipment on models, which, by their very description, gave motorists the implied promise of being appropriate for all seasons. However, there are problems with both of these consumer perceptions. 

What Does and Doesn’t Create Traction 

The primary issue with driving in the winter concerns traction. Traction is essentially a component of friction and weight. In the case of a train, steel wheels on a steel rail are not particularly high in friction, but the locomotive’s weight makes up for it. The weight is far less for cars and trucks, so traction becomes a matter of how well the tire sticks to its surface. This is primarily determined by the tread pattern and depth, the compound characteristics of the tire, and, to a limited degree, the tire pressure, which varies the contact patch. 

So, a given vehicle and its tires on a road surface have a set amount of traction. All- or four-wheel drive does not increase that traction. It can, however, help optimize the traction that is there. Flipped around, it means that AWD or 4WD vehicles are still entirely limited by the traction of their tires. Note that sending power to all four wheels will help get you moving. It can help in steering (though not as much as you might think), and it makes no difference at all in braking. To quote Consumer Reports: “Our test-track observations lead us to advise that using snow tires provides the best grip and assurance for going, stopping, and cornering no matter what you drive: all-wheel drive, front-drive, or rear-drive.” 

Why They Are Now Called “Winter Tires” 

Winter tires are known for their chunkier treads that can push into the snow and then push against it to avoid spinning. But that is only part of the story. Colder temperatures harden all surfaces, and hardness reduces traction. Winter tires are designed to have an appropriate level of softness in freezing weather so they will have greater traction even on dry surfaces. This is why they are now called “winter” tires. They improve traction during colder temperatures regardless of if there is snow on the road. That compound is why you replace them with the advent of warmer weather. The compounds get too soft in warm temperatures, causing the tires to wear too quickly and increase rolling resistance for poorer fuel economy. The chunky treads simply reduce the contact surface on a warm, dry road. The air stirred by those treads also increases noise. 

While innovations in tire compounds and tread designs have made all-season tires better than the tires that preceded them, they still can’t help but be a compromise. The compound has to provide sufficient wear in the summer, yet not get too hard in the winter. Likewise, the tread patterns must provide a happy medium between what works best in winter and summer. 

Cost and Timing 

So, in an area like Indiana, where heavy snow can be expected in the winter, it is still best to outfit your vehicle with winter tires. It may seem like an added expense to have a second set of tires sitting around, but remember that you are only using one set at a time. Tires used only part of the year will last longer, so in the long run you will spend about the same for tires—while always having tires optimized for the season. When should you change the tires? The answer is close to the tip of your nose. A convenient rule of thumb is that if you can see your breath, it is time to be on winter tires.  

There is the expense of having the tires changed, but that cost is low, particularly compared to the benefits. It can also be easily done at the Alderman Automotive service center. Driving in the winter is challenging enough, so don’t take chances with tires that are not fully up to the job.