BRIDGESTONE TIRES: THE SECRET OF MOTOGP
A day at the races
During the San Marino Grand Prix, Hiroshi Yamada, Bridgestone Motorsport Manager, took us “behind the scenes” and unveiled some of the secrets
It is not necessary to be a MotoGP enthusiast to comment on the most recent performances by Valentino Rossi, Marc Marques, Jorge Lorenzo & Co. Events around the MotoGP World Championship are on everyone’s lips, whether sports fans or not. More or less what happens with Ferrari or the biggest football teams. Therefore, everyone is busy talking about lean angles, drifting and braking to the limit, but also about tires whether soft or hard, their performance and wear, and the consequent contribution tires played to someone’s victory or defeat.
As we all know, tires are Paramount in motor racing, regardless whether we are talking about two or four wheels, and particularly so for motorbikes, where things become even more intriguing; MotoGP riders reach well over 300 km/h on a straight, on a contact patch the size of a business card (around 5 square centimeters). A contact patch which automatically shifts from the center to the sides of the tread surface as soon as the rider starts leaning into the corners, and must guarantee adequate grip and the consequent possibility of re-accelerating as soon as possible on the straight. And since the various circuits of the World Championship, such as Sachsenring and Phillip Island, don’t have the same amount of right and left corners, it goes without saying that from time to time one side of the tread is called on to perform more than the other. And this is one of the main issues that the designers must solve to satisfy notoriously demanding customers, MotoGP riders.
A WALK BEHIND THE SCENES
To get to know more about the matter, we took advantage of the San Marino Grand Prix on the Misano circuit, to take a walk, so to speak, behind the scenes and gather some firsthand information, particularly from Bridgestone’s specialists, as the Japanese giant is the sole tire suppliers for the MotoGP World Championship since 2009.
“Shape, structure and compound are only some of the fundamental features of a racing tire” says Hiroshi Yamada, Bridgestone’s Motorsport Manager, drawing on his twenty year experience in this sector. “ We have to guarantee to all riders the best consistency in performance and the best possible grip for as long as possible. That’s why our technical staff works shoulder to shoulder with every rider as well as team managers. Soon after the free practice is over, for example, our engineers examine, using a microscope, samples of the tires just used to gather every possible information necessary to help the teams in making the best possible choice for the qualifiers and the race. Something similar happens – if possible, even more in-depth – in our technical center in Japan as we receive samples of the tires used for the race, which are thoroughly examined to gather useful data to improve future racing and road tires”. It is, in fact, quite unusual that knowledge gathered directly from racing experience is quickly transferred onto products designed for everyday use, as the most recent Bridgestone tires launched on the market clearly show.
This brings us to Kodaira, near Tokyo, where all Bridgestone tires are designed and created in a controlled hospital like environment, using, besides all the data gathered on race tracks around the world, powerful IT systems able to process and simulate the effects of every component used on the tire. If rubber still represents the main component on all racing tires, it is also true that the best result is obtained through skillfully mixing up to 10 different components to produce the best compound possible. It is enough to change any of the components or just confuse the quantities to radically change the characteristics of the tire. The highest accuracy is in fact absolutely essential to ensure safety and performance at more than 300 km/h and the effective transfers of loads that reach up to 2G when braking. Furthermore the layout of the compound can be symmetrical or asymmetrical to guarantee, for example, the best performance on circuits where, as stated previously, there is a greater number of right or left turns.
THE LOGISTIC CHALLENGE
Once the tires have been designed and then physically produced, another daunting challenge arises: making them available to the 25 riders that race, on average, in every Grand Prix. After leaving the factory, the tires are dispatched to Speyer, in Germany, and then loaded on trucks to be delivered to the different European race tracks, or sent directly to non-European tracks such as Laguna Seca, Indianapolis or Sepang, making sure that the tires are delivered no later than the first days of the racing week.
Among the 17 different front tires and 6 rear tires developed by Bridgestone for Grand Prix racing, only 3 different front and 2 rear tires, manufactured just three months before the race, are selected (in addition to wet tires, obviously). This means delivering, for every racing week, something like 1200 tires (although only about half of them are actually used) and a team of 15-18 specialists and engineers.
A QUICK LOOK AT THE TIRES
At this point we take advantage of a momentary brake during the qualifiers to take a closer look at Bridgestone’s MotoGP tires. At first glance every tire displays, just under the shoulder, two bar codes. One is for the manufacturer, and relates to the production of the single tire, while the other allows FIM (Motorcycle Federation) specialists to trace every single tire during the whole racing weekend.
According to the rules, each rider cannot use more than 21 slick tires (10 front and 11 rear) and 10 wet tires (5+5) in a single Grand Prix, and arriving at the race track three days before the start of the free practice sessions, allows Bridgestone’s engineers to work with the FIM in assigning the allotted number of tires for each rider before the first free practice session, and only then, not before, can the tires be fitted on the wheels and made available to the teams and their riders.
After the race the tires end up in an incinerator where they are burned in an environmentally responsible manner as part of an energy recovery program to produce electricity. In short, nothing is wasted.
Racing tires glossary
Abrasion. The wearing down of a tire as it comes into contact with the track surface. The level of abrasion can vary greatly from circuit to circuit and is determined by factors such as the roughness of the tarmac, track temperature and circuit layout.
Lean angle. Also called Camber angle. The inward or outward tilt of the wheel at its uppermost point when compared with the true vertical line at the centerline of the wheel. Generally, the greater the lean angle, the higher the lateral force and so the more demanding on the tires
Asymmetric tires. A slick tire with a harder compound in one shoulder and a softer compound in the other. Designed for circuits that generate higher temperatures in one shoulder than the other, usually because of an imbalance between right and left turns.
Bead. Secures the tire to the wheel rim.
Belts. One of the core components of any tire. They may be made of steel, nylon, polyester or other such materials. Laid on the casing, forms a literal belt around the tire to strengthen its tread area and make it more resistant to punctures.
Chatter. A difficult problem to identify and solve, in which resonant frequencies within various parts of a motorcycle - particularly chassis and tires - combine to induce significant vibration. In serious cases chatter can negatively affect the handling of a motorcycle.
Chunking. Chunking occurs when sections of a tread detach from the tire due to extreme operating conditions resulting in excessive heat build-up.
Compound. Formed by a mixture of various elements used by tire manufacturers to produce treads suitable for any every condition.
Contact patch The contact patch is the portion of the tire that is in contact with the tarmac at any given time. The size and shape of the contact patch varies when subject to forces such as acceleration, braking and cornering.
Graining. A type of tire wear that results in parallel ridges appearing on the surface of the tread. These ridges are aligned perpendicular to the direction of abrasion and in extreme cases, can negatively affect the performance of the tire. Graining usually occurs on high grip surfaces when track temperatures are cooler than optimum.
High-side. An accident that occurs when the rear tire loses grip, either because of slippery conditions, insufficient temperature and too much throttle applied by the rider as well as a number of other reasons, and slides sideways.
Land to Sea ratio. This term (applicable, for MotoGP tires, only to wet tires) refers to the tread to grooves ratio. A tire with a Land to Sea ratio greater than 20% is considered a ‘Wet’ tire.
Low-side. Accident caused by a sudden loss of grip on the front tire, either because of excess corner speed, insufficient temperature or an extreme lean angle as well as a number of other reasons.
Sidewall. The sidewall is the most important element in transferring engine power to the tires as it connects the wheel rim, through the bead, to the tire tread, and therefore the track surface. It has to be stiff enough to avoid severe deformations and plays an important role in absorbing bumps.
Slick tire. A racing tire with no grooves in the tread to be used in dry conditions. Slick tires offer the highest levels of grip in dry conditions by providing the best possible contact patch.
Tire wear. The rate at which a tire is consumed during the race. Mainly affected by the abrasion level a tire is subjected to (softer compounds generally wear faster).
Wet tire. Used for racing in wet conditions. The grooves in the tread help disperse water and improves grip levels.
A MotoGP bike with 4 wheels?
During the 2015 Frankfurt Motor Show, Honda displayed its Project 2&4, a unique single seat with motorbike style mudguards, equipped with the same Honda RC213V engine used in MotoGP, and suitably modified to be used on normal roads; which combines Honda’s 360° technical expertise in mobility on both 2 & 4 wheels. The 4 cylinder V4 and 999cc engine, develops 215 hp at 13.000 rpm and is equipped with a 6 speed Dual Clutch Transmission and a set of Bridgestone Potenza. Honda Project 2 & 4 comes from the idea of offering an intense driving experience, combining the elements of an electrifying motorcycle ride with outstanding emotions behind the steering wheel of a car. This sensation is enhanced by the position of the driver’s seat, just above the road. The design of the "hanging seat" places the driver as close as possible to the action, evoking the freedom of a motorcycle and completing it with the extreme performance of the Honda Project 2 & 4.