The Yeongam circuit in Korea was new to the Formula One calendar last year and has not been used since, meaning that the drivers will be presented with a slippery surface this weekend that will challenge both them and their tires.

Here are some of the other particular demands that the 5615-meter (3.49 mile) Yeongam circuit presents the drivers with:

The track

The first braking area after the start subjects the tires to a big deceleration that peaks at 5G. The cars then drive a flowing part of the track at around 160mph. The rapid esses produce 4.5G of sideways force, which puts a lot of energy through the tires, similar to the last grand prix in Suzuka.

Often the drivers use the kerbs to find the quickest line through the corners. A vertical force of approximately 1764 pounds pushes down on the tires as they ride the kerbs, which places a heavy demand on the tire structure, as it is being put under huge pressure from both above and below.

One of the most challenging corners of all in Korea is Turn 11. This has a wide radius and is driven at high speed. The sticky rubber of the supersoft tire in particular helps to enhance the grip available, allowing the driver to turn in properly and maintain the ideal line throughout the corner.

The final section of track contains a sequence of corners where it is again vital to hold the perfect racing line, working the tire tread hard and heating it up to 248° Fahrenheit.

The end of the lap in Korea contains two particularly challenging sweeping left-hand corners, which the driver has to commit to completely. The front tires need to provide the best possible grip in order to contain understeer at the end of the corner, which leads onto the start-finish straight once more.

Graining

One of the main tire issues on a slippery track, particularly at the start of a race weekend, can be graining. This phenomenon has been an issue at Korea in the past, although Pirelli’s P Zero compounds have so far shown themselves to be quite resistant to graining.

Graining happens when the rubber slides against the track while cornering, rather than obtaining grip. The sideways abrasion against the track surface creates grainy peaks on the tread pattern like waves, reducing the total grip available. The peaks are eventually worn away, leaving a dimple-like effect on the tire that is easily recognizable.

There can be a number of different reasons for graining. An unbalanced set-up can produce excess understeer and the consequent sliding is one common reason for graining the front tires.

Graining can also happen when the tires are worked hard before they are fully up to temperature. If they are not operating at the correct temperature (in the region of 194° Fahrenheit) the grip is reduced as the rubber is not as sticky. This causes the car to slide and the surface of the tread to grain.

Cool ambient temperatures are yet another common factor behind graining. The cooler the ambient temperature, the longer it takes for the tire to warm up – which is why driving a smooth out lap is so important. Generally speaking, both the soft and supersoft compounds reach their ideal operating temperatures within one lap.

Pirelli Tire North America designs, develops, manufactures and markets tires for passenger vehicles in both the original equipment and replacement markets as well as markets and distributes tires for motorcycles and motorsports. Located in Rome, Georgia, Pirelli’s Modular Integrated Robotized System (MIRS) employs state-of-the-art technology to manufacture tires for both export and domestic markets.  For more information please visit www.us.pirelli.com.

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Pirelli Communications and Media Relations – NAFTA Region
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