Wheres the rubber at?

From:  "Dave"

As our car tires wear out where does all that rubber go? Seems to me there should be powder rubber deposits along the road side.

TB faithfully answered this: 

Tires today last 50,000 miles and more. Normal thread wear is dependent on the outer tread or tread cap. The tread cap is typically made with an abrasion resistant, higher grip rubber compound, which works with the tread base and tread design to provide traction and mileage. The amount of tread wear is miniscule - less than dust which is washed or blown off the road. The abraded material is stretched out over the life of the tire which could stretch over 80,000 miles of use.

Todd reported this: 

Basically it goes all over the place. Some stays on the road. Some is airborne. Some is on the side of the road. Tires don't really make a powder as they wear out. Small pieces break off but it isn't a powder.

i know all wanted to help out with this: 

the rubber is on the roads. you know how when you skid there is that black line? that is rubber from the tire. on a normal time there is not that rubber that comes off so you do not see it

David K responded with this: 

I think the amount of rubber that gets worn off a tire is microscopic at any point in time, and these microscopic particles get dispersed into the air by the wind, so you won't notice any accumulation of rubber residue on the pavement.

tomatolord sent us his views: 

The tire companies studied this long long ago.
They found the tires wear away at a very minute level. So that the material is blown away, and becomes part of the dirt, without causing any toxicity

Pavolka added this thought: 

There is. It's just that the particles are small enough to mix in with whatever else is there. They are also spread a good bit by the wind.

Edwin summed it up with this: 

A tire will need to be replaced after AT LEAST ten YEARS. And if you've ever seen a tire in this condition, you'll see that it isn't even really worn down, only the tread is worn down; the tire still has basically the same thickness. So that's just a tiny bit of lost rubber over AT LEAST a decade, which is of course extremely minimal - this is why you don't see rubber powder on roads, there just isn't enough coming out of tires. Also, one could imagine that the small amounts of rubber that do get worn out of the tire end up getting smushed onto the road because of the weight of the car, so if you were to see any rubber due to tires getting worn out, it would appear as marks stuck on the road, like you see when a person breaks very hard.