15 replies to this topic

[senna #1]

PeterWindsor brought up JPMs spin at Australia and said that he kept his old tires because he didn't have any scrubbed ones to put on. How many laps does it take to scrub a set of tires? Does this mean that the teams who opted out of the extra time on Friday won't have enough time to set up the car for the Race and Qual and scrub tires? Is the advantage of the scrubbed tires the fact they are already seasoned and come up to optimal level quicker or driver preference?

[Paolo]

Scrubbing tyres takes usually one or two laps, to be made at moderate speed.
Of course, last years' Michelins required 10 laps or so before stabilyzing, but since those were race laps, it is improper to talk of scrubbing there.
Scrubbed tyres are indeed a lot more consistent, but , at least with some compounds , they lack the ultimate performance of a brand new set.
Unscrubbed tyres will be therefore the best choice for a single fast lap, but their performance will then drop rapidly.
These are rules of thumbs, anyway : it changes a lot with different types.

[Group B]

Scrubbing tyres takes usually one or two laps, to be made at moderate speed

Does that mean that "unscrubbed" tires - those which start a race brand new and immediately do hard fast laps - will not ever be as good as scrubbed tires?

[Aubwi]

I wonder why Michelin and Bridgestone don't pre-scrub the tires before they supply them to the teams. Surely there's some manufactuing process they could do to make the equivalent of a scrubbed tire.

[Group B]

Originally posted by Aubwi
I wonder why Michelin and Bridgestone don't pre-scrub the tires before they supply them to the teams. Surely there's some manufactuing process they could do to make the equivalent of a scrubbed tire.

It's a good question. Maybe different chassis (teams) have different requirements / interactions?

[karlth]

Originally posted by Aubwi
I wonder why Michelin and Bridgestone don't pre-scrub the tires before they supply them to the teams. Surely there's some manufactuing process they could do to make the equivalent of a scrubbed tire.

If Michelin were to pre-scrub the tyres they would probably contradict FIA rules due to insufficient groove depth.

[Aubwi]

Nah, they could just make the tires that much bigger before they scrubbed them.

[zppd]

why is a scrubbed tire better then a brand new one? and if a scrubbed one is better, then why don't Bridgestone & Michelin manufacuture a tire that is just as good brand new as when scrubbed, saves time and energy to scrubb the tire and why not take the advantage all the way?

[Paolo]

Because it is impossible.

[karlth]

Originally posted by zppd
why is a scrubbed tire better then a brand new one? and if a scrubbed one is better, then why don't Bridgestone & Michelin manufacuture a tire that is just as good brand new as when scrubbed, saves time and energy to scrubb the tire and why not take the advantage all the way?

The tyres go through phases ->

Extreme example from 2001 season: 2 laps very fast, 6 laps very slow, 12 laps fast.

Now scrubbing would then mean fitting the car with tyres having run 2+6 laps so they are immediately fast. You'd on the other hand want brand new tyres for a qualifying lap as the first two laps are faster than the last 12 lap's stint.

[karlth]

Michelin's Pierre Duspaquier:

The best lap time with the tyres is always the first lap. Then, since we use threaded tyres with grooves, the process in building up temperature in the front and in the rear tyres makes between the third and eighth or tenth laps tricky to drive. The driver and the car have to find the right balance and the tyre is in the process of stabilisation. Then after 8 or 12 laps you reach this stabilisation and then the tyres are stabilised and even going better and better because of the load reduction because of fuel consumption.

[kober]

http://www.avonracin...tech/advice.htm

[Group B]

Thanx kober - most informative.

[F1 Rumors]

Originally posted by Aubwi
I wonder why Michelin and Bridgestone don't pre-scrub the tires before they supply them to the teams. Surely there's some manufactuing process they could do to make the equivalent of a scrubbed tire.

'cos then they wouldn't be homogenous -- the chemical composition of the surface would be different to the remainder of the and the tyres would not conform to the rules.

[senna #1]

Thank you to eveyone for the info. But I am still wondering if this means the teams who chose unlimited testing will not be able to scrub enough tires for the race. Does anyone know how many laps the new Michelins take to be seasoned? With the reduced practice times, can the unlimited testing teams afford to spend 5-15(most?) mins per set to scrub tires when they are trying to find optimal set up for race and pseudo-qualifying?

[Christiaan]

kobers article confirmed my speculation. the compound does change with temperature and pressure. As Karlth said it would breach regulations to supply pre-scrubbed tyres. I think the teams are supplied the tyres on race weekend by FIA, so its up to each team to do as much scrubbing as they can during the practice sessions.