In 2010, the Korea International Circuit registered the greatest decrease in lap times between first practice and qualifying as the circuit rubbered-in: the pole time was 5.302 seconds faster than the quickest time in practice one, compared to an average dry weather improvement of around 2.5 seconds. That’s typical for a new circuit on which the cars are running for the first time, and also strongly characteristic of little-used street circuits. But what exactly happens during the processing of ‘rubbering-in’? Here’s an explanation…


In what condition does the circuit usually begin the race weekend?
Almost all circuits begin the weekend in a condition that is termed ‘green’ - even if rubber has been laid down on the racing line, any previous running will not have been with the same sticky tyres as used in Formula One.

What happens when a circuit rubbers in?
‘Rubbering-in’ describes the process by which tyre rubber is deposited on the racing line as a result of the 24 cars running during practice. This forms a layer of rubber on the track, which is then compressed on the racing line and increases grip levels. As the cars run around, they also clean the circuit: dust and grit on the track surface are either picked up by the tyres, or blown away by the aerodynamics on the underside of the cars.

How does temperature affect this process?
The tyre choice made by Pirelli for each event takes into account the historical air and track temperatures, to ensure that the selection is appropriate. A historically hotter track may therefore require a harder compound, because softer rubber might wear too fast. The effects of temperature on the process of rubbering-in are secondary to compound softness.

Has the process of rubbering-in changed significantly with the Pirelli tyres used in 2011?
There haven’t been any significant changes compared to previous years, as the compounds do not appear to be particularly softer or stickier than last season. However, the tyres do wear more, so while the circuits do not rubber in to any greater extent, the marbles produced by the tyres are more significant than last year.

What’s the difference between rubbering-in and the formation of marbles?
Marbles are small chunks of rubber thrown off the tyres, which collect off the racing line, and are a function of the tyres’ wear rate. They are therefore not flattened down, and give the same effect as driving on marbles if the driver runs off line. Equally, the dust and grit that is cleared from the racing line does not clear from other parts of the circuit, which means the penalty for running off line at a dusty circuit generally increases as the weekend goes on.

Does the circuit configuration make a difference to how a circuit rubbers in?
Yes: the more cornering involved over the lap, the more rubber is laid down. In Korea last year, the best sector time in the first sector improved by 3.2% between first practice and qualifying, and 45% of this sector is spent cornering. In comparison, the times in sector two improved by 6.2% (79% of sector spent cornering) and in sector three by 6.7% (77% spent cornering).

Which circuits rubber in most significantly?
Generally, street circuits - Monaco in particular, and Melbourne, Singapore and Valencia to a lesser extent. At circuits like these, times will generally come down by 5.5% (up to five seconds) from the beginning of practice to qualifying. The other factor to remember is overnight rain: a reasonable amount of precipitation will result in a return to almost completely green track conditions, with a loss of up to two seconds of lap time.

* Official photo and details courtesy of MERCEDES GP PETRONAS *

Copyright © 2011, Mercedes-Benz-Blog. All rights reserved.

The Korean Grand Prix, Round 16 of the 2011 Formula One World Championship, will take place on Sunday 16 October at the Korea International Circuit in the South Jeolla region. Just seven days after the Japanese Grand Prix, the Yeongam track will host its second race after making its debut on the calendar in 2010.


• At 150 m, the run to the first corner is the third-shortest of the year - after Monaco and Turkey (both 120 m)
• Last year´s race featured 26 laps behind the Safety Car, equivalent to 146 km or 47.3% of the race distance
• At the time, this was the most laps completed behind the Safety Car in a race - until exceeded in Canada 2011

Michael Schumacher
“Visiting Korea for the first time last season was an interesting experience, and I enjoyed learning the new Yeongam track. It’s a very impressive facility, and the track has enough challenges to make it enjoyable to drive. We also had a good result there as I equalled my best result of the season, finishing the race in fourth place. We have enjoyed some encouraging race finishes since the mid-season break, having worked hard to improve our performance. I hope we can carry that trend through to Korea this weekend and then to the remaining races.”

Nico Rosberg
“I’m looking forward to racing in Korea: I really enjoy the track and, for the first race last year, it was certainly a full house spectator-wise. I’m certainly aiming for a more successful weekend than last year, when I was taken out in an accident with Webber on the second lap at racing speeds after the Safety Car came in. We learned in Japan that our performance has taken a small step forward since Singapore. I hope we can make the next one this weekend.”

Ross Brawn, Team Principal
“Having completed the weekend in Suzuka, the team has now packed up and headed to South Korea for the second leg of the season’s final set of double-header races. The Korea International Circuit made its debut on the calendar last year, and the venue combines impressive facilities with an interesting and demanding track layout for the drivers and engineers. We delivered a strong race performance in Suzuka after not the smoothest of weekends, so our focus in Korea will be on getting the most of our current technical package and continuing our recent run of results.”

Norbert Haug, Vice-President, Mercedes-Benz Motorsport
“The Korea International Circuit at Yeongam presents a very complete challenge for the cars and the drivers: long straights in the opening sector, and then a much tighter second half of the circuit, which includes some blind corners and tricky, narrow sections between concrete walls. This contributes to making the average lap speed one of the lowest of the year for a permanent circuit, at around 205kph. Last year´s inaugural race saw very challenging weather conditions and four Safety Car deployments; although we hope for better conditions this year, there remains a reasonable chance of Safety Car periods due to the limited run-off areas. Indeed, the Mercedes-Benz SLS AMG Safety Car has been deployed in each of the past four races. We enjoyed a stronger weekend in Suzuka and delivered quite a competitive team performance. Our challenge will be to perform at this level on a very different type of circuit and, as we have managed at three of the last four races, to finish in the points among the top three teams.”

* Official photo and details courtesy of MERCEDES GP PETRONAS *

Copyright © 2011, Mercedes-Benz-Blog. All rights reserved.