MOTO GP TIRES
MotoGP
Tires
One of the most remarkable things about World Championship motorcycle racing is the way in which the transfer of the phenomenal power of the MotoGP bikes takes place through tyre-contact patches not much bigger than the size of a credit card.
In comparison with racing cars, motorcycling's four-wheeled counterparts benefit from having roughly ten times as much tyre-contact surface - so it is an understatement to say that with 240 horsepower at their disposal tyre selection is critical for MotoGP riders. The power delivery to contact surface ratio is much greater than in any form of car racing.
There are three tyre manufacturers working in the World Championship.
French company Michelin
Japan's Bridgestone in MotoGP
United Kingdom Dunlop in the 250cc and 125cc classes.
Teams
Bridgestone MotoGP supplier only 2009
Repsol Honda
Tech3 Yamaha
Fiat Yamaha
Honda LCR
JiR Team Scot
Ducati Marlboro
San Carlo Honda Gresini
Kawasaki Racing
Alice Team, Rizla Suzuki
Rules
New tyre regulations brought in for the 2008 season tweaked the amount of tires the MotoGP teams can give each of their riders at each Grand Prix. The restricted quantity of slick tires that each of the teams riders may use at a single event is as follows:
During all practice sessions, warm up and the race a maximum of 40 slick tires may be used, specifically - Front tires: 18, Rear tires: 22.
Tire Manufacture
The compounds used in MotoGP are combinations of synthetic material and naturally sourced rubber which is vulcanized and transformed into latex at the manufacturers’ respective factories in France, Japan and the UK. A typical race tyre comprises rubber, high tech plastic fibers, resins and minerals, combined to produce the highest level of performance.
Choosing a Tire
The choice of exactly which compound to use during a race is undertaken by the teams following consultation of the data collected previously at the track by themselves and their tyre supplier. Furthermore, conversations with their riders based on knowledge of the circuit, weather conditions and the feel of the bike on test days, free practice, qualifying and the pre-race warm-up sessions also affects which tires are selected.
On test days and during practice sessions riders often undertake race simulations where they ride with the sort of tyre they would expect to use during the race at whichever track they are practicing at, undertaking the number of laps a race entails at the respective venue. These exercises are crucial for their team and manufacturers in terms of the data they yield and the feedback they produce.
For races a critical balance has to be found between grip and the endurance of the tire - with all available data being used to make the decision on whether to opt for a soft gripping tyre which will permit quicker speeds and faster lap times but wear out quickly, a harder, less sticky tyre which will be more durable but will not assist the rider as much in achieving maximum velocity, or a tyre somewhere in between the two extremes.
Race tires are designed to perform at optimum level for a race distance of around 120 km, whereas specially modified qualifying tires are intended to perform for one or two quick laps only – a matter of just a few kilometers.
Normal race tires are slicks, which differ from the tires used on everyday vehicles in that they are far more adhesive to the ground but far less durable. Race tires can vary tremendously and are chosen according to the expected temperature, the type of asphalt, the demands of the bike and the riding style of riders.
To complicate matters still further, the requirements for front and rear tires can vary massively from a technical perspective and getting the choice right at both ends is critical to success on the track.
Wet Races
For wet conditions, special wet tires with full treads can be used, but they deteriorate quickly if the track dries out. Intermediate tires are used in conditions too wet for slicks and too dry for wets, made with rubber compounds slightly softer than slicks and cut with treads like rain tires – but with shallower grooves to prevent excessive heat build up and deterioration.
Races are categorized as either wet or dry before they start, but a white flag being waved at the flag marshal post during the race indicates that the Race Direction have decided to declare a wet race after it was originally declared dry. In this instance riders may change bikes mid-race from their original slick-shod machine to one equipped with either wet or intermediate tires.
Thus far having been introduced in 2005 the white flag rule has only been enforced three times and the first instance at the GP of Portugal in 2005 took place so late in the race that the riders stayed on their dry bikes. However, at Phillip Island in 2006 and Le Mans in 2007 the rain fell early and heavily enough to warrant a change of bikes, which led to the dramatic spectacle of the entire MotoGP grid entering the pit lane mid-race to swap machinery.
The rules also dictate that once a race is declared wet from the start, a rider can come into the pits to change bikes whenever he decides as long as the type of tires to be used is different.
Influence of tyre restrictions
Due to the tyre restriction regulations, each MotoGP team has to collaborate closely with the representatives from their relevant supplier in order to make critical choices in a pressurized set of circumstances. The recently increased number of barcoded tires (up to 40 for the 2008 season, from 31 in 2007) are chosen on the day prior to the start of official practice before a Grand Prix weekend (usually a Thursday), and each barcode is scanned by the Technical Director who is the head of the scrutinizing team. As the weekend progresses, the barcode on each tyre used is scanned by the scrutinizing team to ensure they are part of the originally recorded allocation.
