F1

The turning removes debris from the tyres and warms them up.

initially every car will have brand new tyres ... so there wont be any chance for debris to stay over it

to warm up the tyres

http://answers.yahoo.com/question/index?qid=20090617141103AAsaIy9

Then, maybe the answer is that it's just fun to do.

Note that I spelled tires the English way even though I'm from USA.

How do you say?? My head is off to you for writing tyre. King James would liking you.

whatever ...

Lynlynch is correct. The heating of the tires makes them more able to handle turns and maneuvers while removing any small undesirable loose crap.

Agreed. F1 tires don't grip worth a damn until they warm up. The same is true of the brakes, by the way. If you don't drive a F1 car FAST, you can't drive it all since you can't corner and can't stop.

This was on Top Gear (BBC America). Great show if you like cars, or if you don't.

You may have seen dragster drivers perform a "burn-out" prior to their run. This is done to warm the surface of the rubber of the tires. The tires stick to the pavement much better at an optimum surface temperature, usually about 220 degrees f. You will see crew members using infrared thermometers to check tire surface temperature during pit stops. It is important to keep tires near their optimum surface temperature for best handling. Therefore, the zig-zags.

To cause friction between the track surface and the tyre surface. In doing so generates heat, which in turn causes the tyre to become softer and the surface stickier. Hence more grip for a faster start (less wheel spin). The zig zagging motion generates and retains heat in the tyre. So that the tyre doesn't cool down too much while they are static on the grid awaiting the start.

Also after coming down from full operating temperature, the tyres will become smooth and what is called "greasy". the back and forth motion cleans the surface, but the true reason is to "scuff" them, basically roughing them up a bit. You will not put any substantial temperature into the tyres by using this movement. If you watch closely before a race, they put tyre warmers on the wheels not just to warm them up, but to soften the tyre compound.

also with the smooth tires, races will be call due to rain sooner than one thinks it should, the smooth tire will hydroplane.

Aren't F1 tyres grooved? I thought they did that to slow them down?

I thought their was a small hole for gauging tread, or surface depth

phoenix911,

You're right. They went back to slicks in 2009 and took away down force to slow the cars.

Cheers.

they went back to it?????........I didn't know they left. tells you not of a avid F1 race fan of late.

Where have you been in the last 50 or so odd years, I ask. ... Oh watching Nascar on rainy days ... sorry.

Debris: The small amount of debris on a tyre as it goes into a turn is determined by how much off line pavement it has covered. If you watch, the driver will stay on the 'line' until the very last second as he grids his car. This is to minimize debris pick up. This debris will be shorn off in the entry to the turn. If you spend too much time off the normal 'line' the tire will be covered in 5-8 mm of used rubber, and will have much less than optimum traction. This cannot easily be removed on the track. Staying on the line prevents this, as the little shreddings are kicked / shed to the outside of the 'line', where they lie in wait for the unwary. They first act as little ball bearings, but also melt-on / build up on the tires if you stay there too much.

Heat: The tire warmers keep the whole tire near its optimum. In the early 70s, I used an array of (12v) resistance elements in the tire's air space to warm it. Not as noticeable as the current F1 blankets, (I did not want to raise suspicions) although there was no rule as such back then... The surface of the tire at mid race will be much warmer than its average. The compound is designed to be its stickiest at that temp. The short periods of severe understeer do this surface warming, bringing the tire to near its mid race temp profile. I have seen less skilled drivers lose control during this maneuvre! The rear tires can be spun for the same effect. I have tried temporarily serious toe-in on my race car to warm the outside surface before competition, but the car becomes too hard to control even in a straight line. Not a good idea!

How about a cycle fender on each front tire lined with a high intensity IR source? With KERS, you have a high capacity electrical system now...

How about a 'shoe brake' acting on the outside of the front tires to pre-warm them...

Decades ago, a memorable Indy 500 TV commentator once said of this trick: "Looks like the drivers are trying out their steering before the big race..."

Same reason a stock car driver does and a drag racer does a burn out, to clean and heat up the tires so they stick to the road better. -- JHF