Marbles

[peasant]

Why have them? I'm Lost? If someone can enlighten me why they have to be there please do.

[beachgirl]

"Marbles" don't have to be there. "Marbles" are the bits of rubber that are worn/flung off the tires as the tires wear, and they end up where they do because of aerodynamics. An egineering mind can explain this in greater detail than I can

[Gluaistean]

"Marbles" don't have to be there. "Marbles" are the bits of rubber that are worn/flung off the tires as the tires wear, and they end up where they do because of aerodynamics. An egineering mind can explain this in greater detail than I can

I have been disqualified immediately.

[beachgirl]

I have been disqualified immediately.

I'm sorry! You're undisqualified - go for it!

[Jag_Warrior]

No joke, I was afraid this was going to be some bad news about the poster, "Marbles". Glad it's not that.

I guess they could go to a harder, longer wearing compound that doesn't wear as quickly, and that would lessen, but not eliminate, tire wear. It would also reduce grib and cornering capabilities. But as long as the tires are made of rubber and the surface is abrasive, and the tires are being pushed to the limit, there's going to be some amount of wear and debris. I used to race R/C cars and even with those small, foam and rubber tires, there'd be clag/marbles on the edge of the track.

[peasant]

No joke, I was afraid this was going to be some bad news about the poster, "Marbles". Glad it's not that.

I guess they could go to a harder, longer wearing compound that doesn't wear as quickly, and that would lessen, but not eliminate, tire wear. It would also reduce grib and cornering capabilities. But as long as the tires are made of rubber and the surface is abrasive, and the tires are being pushed to the limit, there's going to be some amount of wear and debris. I used to race R/C cars and even with those small, foam and rubber tires, there'd be clag/marbles on the edge of the track.

So the rubber technology doesn't exist to prevent them?

[Easy Drifter]

Right. You got it.
If the compound is perfect and the track temprature and humidity is exactly right and nobody goes faster than expected (or slower) and nobody gets sideways and a 1,000 other variables there will be no marbles.
Good effing luck.

[peasant]

Right. You got it.
If the compound is perfect and the track temprature and humidity is exactly right and nobody goes faster than expected (or slower) and nobody gets sideways and a 1,000 other variables there will be no marbles.
Good effing luck.

Why does the rubber have to be so soft?

[Easy Drifter]

It doesn't.
It could be made harder. Then less grip. More wheelspin. More sliding. Tires get too hot and guess what? Marbles.
With the stress put on the tires you will always get marbles to some extent. A compound can be perfect for part of the track but a different loading in another corner or a different surface such as a concrete patch could cause the tiny bits of rubber to come off.
The amount of downforce and cornering speeds of todays cars make it an absolute.
Sometimes the tire manufacturers get it completely wrong. Michelin at Indy on the F1 cars or Goodyear on NASCAR at Indy last year are two cases where the compound was wrong.
Making race tires is still a bit of a black art. Pun intended

[Nem14]

Why does the rubber have to be so soft?

For grip.

[peasant]

It doesn't.
It could be made harder. Then less grip. More wheelspin. More sliding. Tires get too hot and guess what? Marbles.
With the stress put on the tires you will always get marbles to some extent. A compound can be perfect for part of the track but a different loading in another corner or a different surface such as a concrete patch could cause the tiny bits of rubber to come off.
The amount of downforce and cornering speeds of todays cars make it an absolute.
Sometimes the tire manufacturers get it completely wrong. Michelin at Indy on the F1 cars or Goodyear on NASCAR at Indy last year are two cases where the compound was wrong.
Making race tires is still a bit of a black art. Pun intended

Do tyres have to degrade that way? Is there no options technologically?

[Easy Drifter]

1. Yes
2. No

[beachbum]

Marbles exist because tires wear. Tires wear because they develop maximum grip when they are sliding a small percentage. One of the positives of wear is that is gets rid of some heat as hot rubber is pulled from the tread. If a tire didn't wear, it would overheat. These particles can exist as very fine particles or dust or as larger particles. Since the rubber is very hot, particles tend to stick together giving "marbles".

Ever hear the statement that the track "rubbered up"? Rubber sticks better to rubber than to asphalt or concrete, so as tires wear, they put some of that hot rubber into the imperfections of the track, improving traction. One of the reasons dragster do burnouts is to put down a coating of hot rubber.

Put a hard tire on a low powered vehicle, and it slides around, is sometimes unpredictable, but doesn't create marbles. It may create dust, which is just as bad as it doesn't give any traction either. But on a high powered car, the hard tire can spin, overheating the tire. Since the outer surface of the hard tire isn't wearing off, the heat just builds. This is what sometimes happens in NASCAR when tires blow from overheating. That is something you don't want in open wheel.

If a tire is too soft, it may "go off" as the thread gets too hot and just tears off. That causes a performance drop off, but also gives more "marbles".

It is all a compromise.

[shazbot]

Marbles are not an issue on banked ovals as they tend to 'roll down' the hill and settle on the grass.

[shazbot]

Er, no - it's called gravity. Once the marbles have been thrown they loose their 'centrifugal' force and roll back down. Physics.