I don’t understand why basketball and other court shoes have treads on them. I also don’t understand articles like this one.

Doesn’t simple physics tell us that increased surface area means more traction? Isn’t that the whole concept behind drag racing slicks that have no tread? They grip the road better because more of the tire comes in contact with it. Shouldn’t it work the same way with shoes?

It works that way unless there’s anything betweenthe surfaces (shoe and floor in this example). If the floor were even a bit wet, say from sweat from all those players running around, when you step in it you’ll pretty much hydroplane and slide. The treads allow shallow spaces for the fluid to go so the raised treads can make contact with the floor. Same thing for racing slicks, the track must be dry and clean or the whole thing goes wonky.

The anecdata I can offer is that my basketball shoes are getting terribly low on tread and they suck.

However, the tread on a basketball shoe is smoother than the tread on, say, hiking boots for the reason zoid mentions. There’s not as much between the shoe and the court as there is between the boot and the trail.

Zoid has explained the potential for a smooth sole to hydroplane if there’s any liquid present at all.

As for dry friction, the most basic model is the Coulomb model, with says that available traction force is equal to the normal force (in this case, the weight of the player) multiplied by the material’s friction coefficient. Since increasing the contact surface area doesn’t increase the weight of the player, it won’t increase the available traction force, according to this model of friction.

The thing with dragsters (and most track-racing cars/motorcycles) is that the tires are made of material that becomes sticky when it gets hot. It’s like coating the tires with rubber cement, and the Coulomb model no longer applies: as the normal force is reduced toward zero, the available traction force does *not/i] also fall toward zero, so you can indeed get more traction with more surface area.

Treads also help for directional travel. There’s a lot of pivoting on the balls of your feet and most basketball shoes have a kind of circle under that area to anchor and aid in turning (I presume).

I knew there had to be a good reason why multi-million dollar NBA players weren’t risking injury in shoes like that. Now it makes sense. Thank you.