Tires

 

"The aim of a driver and his team in setting up the car is to ensure that the tires operate in the best possible conditions. Only in this way will a tire, which is one of the fundamental components of a Formula1 car, perform to the limit of its potential"
Ayrton Senna from his book" Principles of Race Driving"

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On road car and on high performance racing car, they are look almost the same, round black rubber thing rolling on the road. But hire all similarities stop. In fact, everything is different, except color.

Despite some genuine technical similarity, race tires and road tires are distant cousins. An ordinary car tire is made with heavy steel-belted radial plies and designed for durability - typically a life of 16,000 kilometres or more.

A Formula One tire is designed to last for, at most, 200 kilometres and - like everything else on a the car - is constructed to be as light and strong as possible. That means an underlying kevlar, nylon and polyester structure in a complicated weave pattern designed to withstand far larger forces than road car tires. In Formula One racing that means anything up to a tonne of downforce, 4g lateral loadings and 5g longitudinal loadings.

The racing tire is constructed from very soft rubber compounds which offer the best possible grip against the texture of the racetrack, but wear very quickly in the process. The dry 'grooved' tires are typically designed to function at between 90 degrees Celsius and 110 degrees Celsius.

The development of the racing tire came of age with the appearance of 'slick' tires in the 1960s. Teams and tire makers realized that, by omitting a tread pattern on dry weather tires, the surface area of rubber in contact with the road could be maximised. Formula One cars ran with slicks until the 1998 rule changes came into effect, and new tire standards were introduced in an attempt to improve the spectacle of Formula One racing by reducing cornering speeds.

This led to the familiar sight of 'grooved' tires, the regulations specifying that all tires had to have four continuous longitudinal grooves at least 2.5 mm deep and spaced 50mm apart. These changes created several new challenges for the tire manufacturers - most notably ensuring the grooves' integrity, which in turn limited the softness of rubber compounds that could be used.

A tires shape is not a simple cylinder, the tire in fact has a complex shape, as the tire deforms in both side and front elevation as it contacts the track. This shape changes with steering and speed/downforce. Mapping this complex dynamic shape is important as it will feed back to correlate to the shape seen on the rubber wind tunnels tires provided by supplier and also modeled in CFD. The shape changes are subtle, but equally very different from tire to tire the flow off the front wing and around the rear end will be heavily influenced.

2009 season brings a much-welcomed return to slick tires, following the FIA's decision to limit aerodynamics rather than rubber as a way of keeping cornering speeds under control.

The 'softness' or 'hardness' of rubber compounds is varied for each race according to the known characteristics of the track. Two different compounds are available to each team at every Grand Prix weekend, and every driver must make use of both specifications during the race. The actual softness of the tire rubber is varied by changes in the proportions of ingredients added to the rubber, of which the three main ones are carbon, sulphur and oil. Generally speaking, the more oil in a tyre, the softer it will be.

 

Bridgeston Potenza Formula 1 tires, left slick, for dry track, middle Intermediate, for partially wet conditions, and right full wet tires for rain conditions

 

Intermediate and wet-weather tires have full tread patterns, necessary to expel standing water when racing in the wet. One of the worst possible situations for a race driver remains 'aquaplaning' - the condition when a film of water builds up between the tire and the road, meaning that the car is effectively floating. This leads to vastly reduced levels of grip. The tread patterns of modern racing tires are mathematically designed to scrub the maximum amount of water possible from the track surface to ensure the best possible contact between the rubber and the track.
The intermediate tires are generally used in partially wet conditions, where the driving surface is neither completely dry nor absolutely drenched. They provide moderate assistance in both conditions and are hence favoured when half the circuit is experiencing rain and the other half remains dry.
Heavy grooved, full rain tires will come into play in case of rains. When the treads in the tires, come in contact with the track, they expand a little, due to the downforce and the weight and absorb enough quantity of water to bring the tire back in contact with the track. When the water soaked area of the tire lifts off the track, it contracts again and releases the water. Thus tires play an important safety role by keeping the car from sliding off uncontrollably.

Formula One tires are normally filled with a special, nitrogen-rich air mixture, designed to minimise variations in tire pressure with temperature. The mixture also retains the pressure longer than normal air would.

Size of the front tire is regulated to be between 305 and 355mm, and rear between 365 and 380mm. Unlike the fuel, the tires bear only a superficial resemblance to a normal road tire. Whereas a road car tire has a useful life of up to 80,000 km, an Formula One tire is built to last a bit more then one half of race distance (a little over 200 km).
This is the result of a drive to maximize the road-holding ability (grip), leading to the use of very soft compounds (to ensure that the tire surface conforms to the road surface as closely as possible.

Since the start of the 2007 season Bridgestone is the exclusive tire supplier and have introduced five compounds of tire, two of which will be made available at each race. The harder tire is more durable but gives fewer grips, and the softer tire gives more grip but is less durable.

Both compounds supplied by maker have to be used by teams during one race and the softer tire of two, until 2009, has a painted green stripe on the inner and outer sidewalls of the tire. This was introduced after the first race of the season when confusion occurred because a small dot was put instead of the white stripe.

Each team must use each specification during the race, unless wet or intermediate tires are used during the race, in which case this rule no longer applies.

 

Official F1 tire supplier Bridgestone have now, middle of February 2009, settled on how to differentiate its compounds of dry-weather slick tires. Last year, 2008, the 'hard' and 'soft' compounds on offer at grands prix were differentiated by painting the inside of one of the four grooves white, so that the type of tire being used by a driver on the circuit is visibly apparent to spectators. With the return this season of slick tires, however, the Japanese manufacturer has been contemplating what method to use in 2009 and beyond. It was speculated that full colored sidewalls were considered, and various other methods have previously been tested, including different colored rings - including white and purple - on the sidewalls. But perhaps the best solution so far, which with just over 40 days to go until Melbourne must surely be the frontrunner, was in evidence as five teams on circulated at the Spanish test circuit in Jerez de la Frontera in preseason testing. As seen on the cars of Nelson Piquet (Renault) and Kazuki Nakajima (Williams), the solution involves the use of thin green painted lines circling both the inner and outer sidewalls on the front tires, and the inner sidewalls on the rear. The effectiveness of the solution was apparent when the colors could easily be distinguished both when viewing the cars from the side as well as from the rear.

 

From 2010, only tire change is allowed during pitstop. Refueling is banned, and drivers have to start with all fuel needed for race. This will put additional load to tires because until now, car was loaded with 50 to 60 kilograms of fuel, and now this load is about 150 to 170 kilograms.

And there is another thing to consider. With refueling, pitstop duration was about 6 to 9 seconds, and a plenty room for good strategy and overtaking trough pits. Without refueling pitstop duration is around 3 to 4 second and strategy should be impeccable. Often this short time can't be used for any meaningful strategy.

But anyway, during pitstop in one typical Formula 1 race there were places to be won and lost to other drivers by mistiming the stop, so how did the teams decide?
The teams have a more sophisticated timing system than the one available to the public and media. It divides the lap into ten sectors, rather than the basic three available for rest of us and this gives them a much faster evaluation of the way the tires are behaving. Rather than wait 20 plus seconds to find out whether they are going off, they can tell every (more or less) 8 seconds how the performance is going.
Engineers and computers study the trends and make the strategy calls based on what they see.
This works in two ways; it tells them the precise moment when their tire compound are losing performance, and by reading the sectors of cars already on different compound, they can see what performance gain rivals are experiencing.
After one driver has pitted and his lap times went from 1m 19.7s (old tires) to 1m 17.6s (new tires - different compound). Rival engineers could see immediately the speed advantage he was getting from his new tires and decide to do and when to do their pitstop.

 

2010 - Out	2011 - In

 

Following Bridgestone’s decision to withdraw at the end of 2010 after 13 years in Formula One, Pirelli take over as the sport’s sole tire supplier. The Italian company, last part of F1 in 1991, will provide all teams with rubber for the next three years.

Tire allocation has been reduced for 2011, with 11 rather than 14 sets of dry-weather tires available to each driver per race weekend. Drivers will receive three sets (two prime, one option) to use in P1 and P2 and must return one set after each session. A further eight sets will then be at their disposal for the rest of the weekend, although one set of each specification must be handed back before qualifying.

If a driver fails to use both specifications of dry-weather tires during a (dry) race, they will be excluded from the results. If a (dry) race is suspended and can’t be restarted, and a driver has failed to use both specifications, 30 seconds will be added to the driver’s race time.

On March 18, 2011 Pirelli has released the details of its color-coding system for its 2011 tire compounds. There will be four slick compounds as well as two wet-weather tires. The Italian company, which takes over from Bridgestone as Formula 1's sole supplier in 2011, has decided to paint its logo in different colors, so that spectators can keep track of team strategy. The color coding is as follows: Wet - orange Intermediate - light blue Supersoft - red Soft - yellow Medium - white Hard - silver Pirelli's motorsport director Paul Hembery think that these will enable both live and television audiences to tell at a glance who is on what compounds, which will be vital knowledge as tires are set to form a key part of race strategy 2011. The tires have been deliberately designed to be less durable than in the past, to force the teams and drivers to make more pit stops and create more unpredictable racing. Pirelli intends to use the soft and hard compounds at the first three fly-away races, with the hard designated "prime" and the soft the "option", before making a decision on later allocations once it has analyzed the tires under race conditions. The F1 rules dictate that there must be a two-compound gap between the two available types of dry-weather tires at each race, so there is no chance of the silver and white being confused as the hard and medium tires will never be used at the same race. Each driver has to use both types of dry-weather tire in the course of a dry race. In a wet race they have a free choice.   Following complaints after first race in Australia that it was difficult to differentiate the silver and yellow colours used for the hard and soft tyres, tweaks have been made for this weekend race, second this seasson in Malesia, as an interim solution. The soft tyres will feature a gold stripe to make them easier for fans to see which compounds drivers are using and to tell apart from the hard

 

To know more see the articles:

What is the most important part of a racing car?
Using Tires
Tire Compouns
Tire Warmers

 

Since the start of the 2007 Formula One season Bridgestone have been the sole manufacturer. Past manufacturers include, ordered by number of races won:

Pos	Manufacturer	Seasons	Starts	Wins	Sole supplier	First win	Last win	World Championships
								Driver	Constr.
1	Goodyear	1959 – 1998	494	368	113	1965 Mexican Grand Prix	1998 Italian Grand Prix	24	26
2	Bridgestone	1976 – 1977 1997 – 2010	244	175	116	1998 Australian Grand Prix	2010 Abu Dhabi Grand Prix	11	11
3	Michelin	1977 – 1984 2001 – 1006	215	102	0	1978 Brazilian Grand Prix	2006 Japanese Grand Prix	6	4
4	Dunlop	1950 – 1970 1976 – 1977	175	83	0	1958 M0naco Grand Prix	1970 Belgian Grand Prix	8	9
5	Firestone	1950 – 1975	121	49	11	1950 Indianapolis 500	1972 Italian Grand Prix	4	3
6	Pirelli	1950 – 1958 1981 – 1986 1989 – 1991 2011 –	200	44	0	1950 British Grand Prix	1991 Canadian Grand Prix	6	0
7	Continental	1954 – 1958	13	10	0	1954 French Grand Prix	1958 Argentine Grand Prix	2	0
8	Englebert	1950 – 1958	61	8	0	1955 Monaco Grand Prix	1958 British Grand Prix	2	0
9	Avon	1954 – 1958 1981 – 1982	29	0	0	N/A	N/A	0	0

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Explanation of tire simbols find on "normal" tires

 

TIRE SIZE

1-Tire width (mm or inch)
2-Aspect ratio in %
3-Radial construction
4-Rim diameter
5-Load index
6-Speed symbol
7-Tire outer diameter (inch)
8-Ply rating

 

 

Beginning in 1991, the speed symbol denoting a fixed maximum speed capability of new tires must be shown only in the speed rating portion of the tire's service description, such as 225/50R16 89S. The most common tire speed rating symbols, maximum speeds and typical applications are shown below:

L	75 mph	120 km/h	Off-Road & Light Truck Tires
M	81 mph	130 km/h
N	87 mph	140km/h	Temporary Spare Tires
P	93 mph	150 km/h
Q	99 mph	160 km/h	Studless & Studdable Winter Tires
R	106 mph	170 km/h	H.D. Light Truck Tires
S	112 mph	180 km/h	Family Sedans & Vans
T	118 mph	190 km/h	Family Sedans & Vans
U	124 mph	200 km/h
H	130 mph	210 km/h	Sport Sedans & Coupes
V	149 mph	240 km/h	Sport Sedans, Coupes & Sports Cars
Z	149 mph +	240 km/h +	Sport Cars
W	168 mph	270 km/h	Exotic Sports Cars
Y	186 mph	300 km/h	Exotic Sports Cars

While a Z-speed rating still often appears in the tire size designation of these tires, such as 225/50ZR16 91W, the Z in the size signifies a maximum speed capability in excess of 149 mph, 240 km/h; the W in the service description indicates the tire's 168 mph, 270 km/h maximum speed.
Most recently, when the Y-speed rating indicated in a service description is enclosed in parentheses, such as 285/35ZR19 (99Y), the top speed of the tire has been tested in excess of 186 mph, 300 km/h indicated by the service description as shown below:

285/35ZR19 99Y	186 mph, 300 km/h
285/35ZR19 (99Y)	in excess of 186 mph, 300 km/h

 

What FIA 2011 FORMULA ONE
TECHNICAL REGULATIONS say about that

12.5 Supply of tyres :
12.5.1 All tyres must be used as supplied by the manufacturer, any modification or treatment such as cutting, grooving, the application of solvents or softeners is prohibited. This applies to dry, intermediate and wetweather tyres.
12.5.2 If, in the opinion of the appointed tyre supplier and FIA technical delegate, the nominated tyre specification proves to be technically unsuitable, the stewards may authorise the use of additional tyres to a different specification.
12.5.3 If, in the interests of maintaining current levels of circuit safety, the FIA deems it necessary to reduce tyre grip, it shall introduce such rules as the tyre supplier may advise or, in the absence of advice which achieves the FIA's objectives, specify the maximum permissible contact areas for front and rear tyres.
12.6 Specification of tyres :
12.6.1 An intermediate tyre is one which has been designed for use on a wet or damp track.
All intermediate tyres must, when new, have a contact area which does not exceed 280cm² when fitted to the front of the car and 440cm² when fitted to the rear. Contact areas will be measured over any square section of the tyre which is normal to and symmetrical about the tyre centre line and which measures 200mm x 200mm when fitted to the front of the car and 250mm x 250mm when fitted to the rear. For the purposes of establishing conformity, void areas which are less than 2.5mm in depth will be deemed to be contact areas.
12.6.2 A wet-weather tyre is one which has been designed for use on a wet track.
All wet-weather tyres must, when new, have a contact area which does not exceed 240cm² when fitted to the front of the car and 375cm² when fitted to the rear. Contact areas will be measured over any square section of the tyre which is normal to and symmetrical about the tyre centre line and which measures 200mm x 200mm when fitted to the front of the car and 250mm x 250mm when fitted to the rear. For the purposes of establishing conformity, void areas which are less than 5.0mm in depth will be deemed to be contact areas.
12.6.3 Tyre specifications will be determined by the FIA no later than 1 September of the previous season. Once determined in this way, the specification of the tyres will not be changed during the Championship season without the agreement of all competing teams.
12.7 Tyre gases :
12.7.1 Tyres may only be inflated with air or nitrogen.
12.7.2 Any process the intent of which is to reduce the amount of moisture in the tyre and/or in its inflation gas is forbidden.

 

 

What FIA 2011 FORMULA ONE
SPORTING REGULATIONS say about that

25) SUPPLY OF TYRES IN THE CHAMPIONSHIP AND TYRE LIMITATION DURING THE EVENT
25.1 Supply of tyres :
A single tyre manufacturer has been chosen by the FIA for the 2011, 2012 and 2013 seasons following an invitation for tenders to supply tyres to all the cars entered in Championship Events for the duration of these seasons. A single tyre manufacturer will be chosen by the FIA for subsequent seasons following an
invitation for tenders to supply tyres to all the cars entered in Championship Events for the duration of such subsequent seasons.
The appointed tyre supplier must undertake to provide :
- two specifications of dry-weather tyre at each Event, each of which must be of one homogenous compound and visibly distinguishable from one another when a car is on the track ;
- one specification of intermediate tyre at each Event which must be of one homogenous compound ;
- one specification of wet-weather tyre at each Event which must be of one homogenous compound.
25.2 Quantity of tyres :
During the Event no driver may use more than eleven sets of dry-weather tyres (six of "prime" specification and five of "option" specification), four sets of intermediate tyres and three sets of wet-weather tyres.
A set of tyres will be deemed to comprise two front and two rear tyres all of which must be of the same specification.
25.3 Control of tyres :
a) The outer sidewall of all tyres which are to be used at an Event must be marked with a unique
identification.
b) Other than in cases of force majeure (accepted as such by the stewards of the meeting), all tyres intended for use at an Event must be presented to the FIA technical delegate for allocation prior to the end of initial scrutineering.
c) At any time during an Event, and at his absolute discretion, the FIA technical delegate may select alternative dry-weather tyres to be used by any team or driver from among the stock of tyres the appointed supplier has present at the Event.
d) A competitor wishing to replace one unused tyre by another identical unused one must present both tyres to the FIA technical delegate.
e) The use of tyres without appropriate identification may result in a grid position penalty or exclusion from the race.
f) The only permitted type of tyre heating devices are blankets which use resistive heating elements. The heating elements may only act upon the outer tyre surface.
25.4 Use of tyres :
Tyres will only be deemed to have been used once the car's timing transponder has shown that it has left the pit lane.
a) Three sets of dry-weather tyres will be allocated by the FIA technical delegate to each nominated driver for use during P1 and P2, two of "prime" specification and one of "option" specification. These are the only dry-weather tyres which may be used during these sessions.
One set of "prime" specification must be returned to the tyre supplier before the start of P2 and one further set of "prime" specification and one set of "option" specification before the start of P3.
If an additional driver is used (see Article 19.1(b) he must use the tyres allocated to the nominated driver he replaced.
b) Eight further sets of dry-weather tyres will be allocated by the FIA technical delegate to each nominated driver, four of each specification, for use during the remainder of the Event. However, one set of each specification must be returned to the tyre supplier before the start of the qualifying practice session and may not be used during the remainder of the Event.
c) Prior to the start of the qualifying practice session intermediate and wet-weather tyres may only be used after the track has been declared wet by the race director, following which intermediate, wet or dry-weather tyres may be used for the remainder of the session.
d) At the start of the race each car which took part in Q3 must be fitted with the tyres with which the driver set his grid time. This will only be necessary if dry weather tyres were used to set the grid time and if dry-weather are used at the start of the race.
Any such tyres damaged during Q3 will be inspected by the FIA technical delegate who will decide, at his absolute discretion, whether any may be replaced and, if so, which tyres they should be replaced with.
e) Unless he has used intermediate or wet-weather tyres during the race, each driver must use at least one set of each specification of dry-weather tyres during the race. If the race is suspended and cannot be re-started, thirty seconds will be added to the elapsed time of any driver who was unable to use both specifications of dry-weather tyre during the race. However, any driver who completes the race without using both specifications of dry-weather tyre will be excluded from the race results.
f) If the race is started behind the safety car because of heavy rain (see Article 40.14), or resumed in accordance with Article 42.5(a), the use of wet-weather tyres until the safety car returns to the pits is compulsory.
25.5 Testing of tyres :
a) Tyres supplied to any competitor at any time may not be used on any rig or vehicle (other than an F1 car on an F1 approved track, at the exclusion of any kind of road simulator), either Team owned or rented, providing measurements of forces and/or moments produced by a rotating full size F1 tyre, other than uniquely vertical forces, tyre rolling resistance and aerodynamic drag.
b) Tyres may be used on a test rig providing forces control and monitoring by F1 rim manufacturers for the sole purpose of proof testing their products.

 

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