Fatter: Sometimes Better?

Eric (Eni) Enescu
Staff Writer


Slick, grooved, low profile, oversized; tires come in all shapes and sizes. Quite a few people, sadly, fall victim to the confusing world of tires.
To clear things up, let’s look at a few concepts. Tires are the fat black things that allow you to drive. Using controlled friction, the wheel and tire assembly transfer engine inputs into motion. The better the tire’s grip, the more friction there is.
When working, a tire flexes and slides, creating heat. As such, tires are designed to function within a temperature window, a working range in other words, tailored to the expected forces. A tire can be optimized for temperature and durability by altering the rubber compound. A compound denoted as softer will have a lot of grip when compared to a harder tire, but has lower overall durability in terms of wear. Every tire is designed around this compromise, depending on requirements.
If you have taken a physics course, you would see that surface area has no impact on friction. However, surface area changes the way the surface of the tire reacts with the ground.
Ideally, for maximum grip, you would want a perfectly slick, wide and flat tire, as the maximum surface area would lead to the greatest amounts of grip. A wider tire will spread the load from accelerating, braking and cornering forces along a larger surface. Wider tires would thus allow for better temperature management, allowing for softer compounds with less wear than a narrower tire. Keep in mind however, certain conditions (such as icy and slushy roads) would benefit from narrower tires, but with spikes.
The grooves you find on the tread are there for two reasons. First, they allow for water to be channeled through the tire, stopping aquaplaning. Second, since the grooves are not as stiff as the carcass of the tire, they produce heat, useful for snowy and icy conditions. More expensive tires from reputable brands will have more advanced grooves and compounds for each required condition. The sequence of the grooves influence grip.
Some tires can work in any way, others only work spinning in one direction (unidirectional) and others are designed to have an inner side and outer side (asymmetrical). Each are designed for specific performance targets.
One thing that often gets overlooked when picking a tire is the construction. The tire is formed by a metallic or polymer belt creating its shape. For optimal function, the tire needs to be stiff in certain spots, for cornering, and have more flex in others, for comfort, while also being puncture resistant. More expensive tires use exotic materials such as Kevlar, making for a stiffer and more responsive tire. The outer shoulder generally tends to be stiffer, on asymmetrical tires, for better cornering and responsiveness. Another trick manufacturers use is tread and sidewall dept. Taller sidewall tires are more flexy than lower profile ones, making them less drivable, but more give makes them softer and more comfortable.
Tires are advanced pieces of engineering. They are just a part of what makes a car work. To make the most of your tires, pick a more performance oriented tire designed for your car, for better safety through better grip. Whatever you do, use reputable tires. Cheap knockoff tires will ruin your life, and your wallet.

Originally Published on bandersnatch.ca