Motionless car with tire spinning on ice causes burning rubber smell?

Question

I live in New England, where "Winter Wonderland" often involves large amounts of ice on the road. A number of times I've had to help someone get their car out of a parking spot where their drive wheels were on ice. Often the driver would (foolishly) floor it, spinning the wheels without accomplishing anything, eventually resulting in the smell of burning tires.

I associate that smell with tires that are overheating due to friction, but there's very little friction when on a block of ice. And, one would think being pressed against ice would be a great way of cooling down the tread. So, what is causing that smell?

My only guess is that the tire tread flexes rapidly as it comes to and leaves the contact patch, which heats (and eventually overheats) the tire compound. If so, then why don't tires get that hot while rolling on the highway, at highway speeds?

Answer 1

Ice by itself can have a decent amount of friction. The lack of friction is caused by a thin layer of water that develops between the sliding device and the surface of the ice. As the device slides over the ice it melts the top layer and a thin layer of water comes about.

A fast moving tire spins the melted water off the ice faster than it than it can be replaced. If you spin it fast enough the ice to tire interface becomes so hot that the water goes directly to steam.

The amount of friction varies with temperature of the ice. The colder the ice the higher the friction. Ice does not have one defined coeffient of friction (mu) because it exists in too many forms and temperatures