If treaded tires have more grip than tires with less tread, why are racing slicks so grippy?
In: Engineering
Tread is useful in adverse driving conditions – rain, snow, ice, mud, gravel, off road conditions, etc. Tread allows for water and snow to displace, and sipes (the edges of the tread) mechanically dig into and grip the road material.
On a well paved surface in ideal conditions, tread serves no purpose.
Racing tires are made of a different compound than normal street tires. The rubber is much softer – in some cases, as soft as a pencil eraser, and when cold, they can be as sticky as duct tape, in my experience, or even more so. Racing tires also have an ideal operating temperature, so those sticky tires need to get hotter by almost 100F to get even sticker to provide maximum grip. Of course, these tires tend to wear out in short order – pit stops in NASCAR and F1, and up to 8 passes in top fuel drag racing – which I find astounding they last THAT long.
These tires are expensive, mostly because they’re made in such low volume, they don’t last, and are completely impractical for a road car.
You can buy summer performance tires for your sports car. I do. They’re a soft compound, much softer than a typical all-season tire, and they have light tread that is D.O.T. approved (and thus legal to be fitted onto a road car and driven on the street), but the tread is purposefully designed to wear off as fast as possible (all this to skirt the law). They produce maximum traction once they wear properly. I’ve never had a set last more than 5 months. I also drive it like I stole it, sometimes.
But take it from me, these tires are suicidal if it rained – yesterday. The high moisture content left on the road days after is enough to greatly reduce traction. I had a friend in a sports car eat it just trying to get out of his subdivision the day after rain. High humidity on a summer evening? Yeah, there’s condensation on the road that can kill you dead even at mundane speeds. You can hydroplane a car even at 10 mph, and ABS isn’t a silver bullet. These tires in the snow? Forget it. I was young, once, and both cheap and poor. A light dusting of flurries, and I was stranded at a stop sign with no traction or ability to move. I had a broom with me to sweep the snow from the front of my tires to get moving.
And that is why no-tread racing tires are called “slicks”. These tires are completely ineffective in any adverse condition, they were designed for one specific use case, and if you have summer tires on your car, and you’re out and about, and it rains, you’re stuck on the side of the road until it clears up, and then you drive home slowly and avoid traffic.
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