Racing tires

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Racing tires in the 2004 Formula 1 paddock in Monza

Racing tires are performance-optimized special tires for use in sporting competition, which differ significantly in terms of material and construction from tires approved for road traffic . They are used in 4- or 2-wheel motor sports as well as in cycling . Different optimized tires can be used for an identical vehicle type depending on the discipline and application. Off-road rally tires , sprint tires , rain tires and tires for long-distance races all differ significantly. In the automobile and motorcycle sector, racing tires differ from performance- optimized sports tires in that they are not approved for road use.

Comparison of road and racing tires

If the life expectancy of a road tire is around 20-50,000 km today, racing tires are designed for a service life of 30 (qualifying tires) to 500 km (long-distance use), depending on the specific application. This is also due to the fact that for almost 100% of its service life the racing tire is in the limit range of its grip properties, whereas this only occurs in exceptional cases with road tires. While the road tires for all properties ( wear , adhesion , wet braking, comfort) is interpreted in terms of a best possible compromise, the racing tires to the border area of a narrowly defined scope (wet or dry, narrow temperature window) is optimized to. The operating temperature also differs significantly for road (5-50 ° C) and racing tires (70-120 ° C). Since racing tires are manufactured in smaller batches and the focus is on performance at all costs for the customer, higher prices are common for the same tire dimensions than for road tires .

Although racing tires have to bear less static load due to the generally lighter vehicle chassis , loads of up to more than 2 tons in extreme cases ( Group C racing cars in Le Mans) can act on a single tire through appropriately efficient aerodynamics . In addition, high rotational speeds result in further high dynamic loads on tires. Every point on a tire tread "hits" the asphalt around 40 times per second at a speed of 350 km / h (e.g. F1, Le Mans, Indycars ). In order to keep the "Laces", i.e. the contact area between asphalt and tires, as constant and as wide as possible even with such extreme loads and additional cornering, racing tires are made with a more angular instead of round contour due to the almost vertical sidewalls and tire shoulders constructed. In addition, additional steel or Kevlar belt layers are installed to stabilize the contour.

Gravel racing tires on a WRC - Citroën C4

A particular challenge for the design is the fact that, despite the required more stable design, the weight of the racing tire must be minimized to reduce the rotating masses. The lighter a tire, the faster the vehicle can accelerate due to the reduced mass inertia. Estimates say that one kilogram saved on the tires corresponds to 5 kg saved on the chassis. Therefore, racing tires of comparable dimensions are on average 30% lighter than road tires.

There are also differences in tire chemistry. In road tires , for example, tread compounds containing silica have found widespread use because of their better wet braking properties. Racing tires, on the other hand, rely on higher soot contents in order to ensure grip under high loads thanks to the temperature stability. Even higher proportions of natural rubber are usually used in road tires, while modern racing tires are made with synthetic rubber. Due to the short mileages play anti-aging agents for race tires as opposed to street tires, no role, while on the other hand adhesive resins and plasticizers (eg. As oils) with racing tires with significantly higher proportions are used.

General

Slicks after a race distance (Formula 3)

Slicks (treadless tires) are permitted in some racing series . They have the advantage that the contact area, which is not large anyway, is not reduced by the "negative" points in the profile. In various rally and hill climb series and in some car classes, for example in Switzerland, only tires with a “negative profile” have long been permitted. This is particularly large with rain tires or intermediates . The rubber compound for rain tires is usually softer than for dry tires.

In many racing series, brand cups, brand formulas up to Formula 3 , the tires are prescribed exactly according to manufacturer and size, with sometimes different manufacturers for slicks and rain tires.

A bad tire can slow a car down by several seconds per lap. In addition, if the load is too high or if the asphalt temperatures are too high, the tires can degrade in the course of a race and even burst at the end of the race. The influence of the tires on the quality of a car is relatively high compared to the importance of the engine , the aerodynamics and the chassis , so that in racing series in which there are several tire suppliers, in addition to the competition from the individual racing teams, the competition from the tire manufacturers is fundamental Role play.

Bridgestone slicks for the 2009 Formula 1 season

History of tire suppliers in Formula 1

The tire manufacturer Pirelli was represented in Formula 1 for the longest time (from 1950 to 1991). Racing teams that used Pirelli only achieved 42 wins. Goodyear had a total of 368 victories in his engagement from 1965 to 1998.

Michelin (from 2001) and Bridgestone (since 1997) supplied the Formula 1 teams until the end of 2006. In some Formula 1 races, it has been observed that the teams that drive a certain brand of tires make the victory among themselves. In the 2005 season in Formula 1, the tires had to hold out the entire distance from qualifying to the end of the race. It was hoped that this provision would prevent accidents caused by tire damage, which was based on extremely lightweight construction. At the US Grand Prix in 2005 , the tire development race went so far that, after a serious tire-related accident during training, the tire supplier Michelin was unable to provide tires that would have withstood an entire race with sufficient safety. As a result, only the 6 vehicles that drove with Bridgestones started. As a result, tire changes in the race and qualifying were again permitted from the 2006 season, instead the maximum number of tires used per race weekend is now limited.

Since one would like to put the competition of the racing teams in the foreground again, in Formula 1 from 2007 only one uniform tire supplier was allowed for all teams. From 2007 to 2010 inclusive , this was Bridgestone. Pirelli has been the exclusive Formula 1 supplier again since 2011 .

After the cornering speeds in Formula 1 became ever higher and the associated dangers were no longer considered acceptable, a longitudinal groove profile was prescribed. Restricting the tire width would probably have had the same effect, but this maintained a certain visual continuity. Due to consistent further development, the cornering speeds continued to increase despite grooved tires, so that the regulation of this profile was repealed with the 2009 season and slicks have been permitted again since then.

The regulations prescribe a maximum rim diameter of 13 inches. The maximum width (different front and rear) is also specified.

Manufacturer and former manufacturer of racing tires in automobile sport

Tire sizes

While the size specifications for car tires are standardized and regulated by regulations, racing tires usually have different dimensions depending on the manufacturer. The common denominator is the rim diameter, which is given in inches and comes last. The width can be specified in inches or metric. The diameter or rolling circumference as well. A typical example of an Avon slick can be:

  • 6.6 / 19.5 × 14

6.6 means the tire width in inches, corresponding to 16.8 cm. 19.5 the diameter of 49.53 cm and 14 the rim diameter, which is generally stated in inches. The indication of the diameter in inches indicates that the tire was manufactured in a diagonal construction. The rubber compound, which varies in hardness depending on the suitability for the race distance, is noted in a manufacturer-specific nomenclature in addition to the actual size specification.

Michelin racing tires:

  • 18 / 67-17 S1826B

Structure of a slick name: 18 / 67-17 S1826B:

18 = tire width in cm
67 = outer diameter in cm
17 = nominal diameter in inches
S1826B = reference for carcass and rubber compound
19 / 67-420: 420 = nominal diameter in mm; 420mm = 16.5 inches.

  • 210/620 R17

210 = tire width in mm
620 = outer diameter in mm
R = radial tire (radial tire)
17 = nominal diameter of the rim in inches

Racing tires

Racing tires for road or track cycling are optimized in the direction of higher grip and lower rolling resistance , while wear is of secondary importance here. The tires are designed to be very narrow with a reinforced construction at the same time in order to allow high internal air pressures to reduce rolling resistance. The tread compound is optimized in the direction of greater grip and is usually designed without a profile.

For trial , outdoor and off-road competitions ( downhill ), on the other hand, wider, treaded tires are used. Different profiles and rubber compounds can be used depending on the weather and the nature of the ground.

Racing tires in drag racing

Start of a Top Fuel Dragster (Jndia Erbacher, CH) in a race at the Rico Anthes Quartermile 2019.

In " drag racing " (a type of motor sport that is all about maximum acceleration) the demands, especially on the rear wheels, are enormous. The tires are specially adapted to the requirements of the races, which are held on tracks specially prepared with rubber and glue . At the moment (as of 2020) only one make of tire is permitted in the top class, the so-called Top Fuel category: The " Goodyear Eagle Dragway Special" This tire is certified up to 563 km / h.

The rear tires are huge at 36.0 × 17.5–16 and have a circumference of around 3 meters. The tires are filled with a very low pressure of just 0.6 bar. They are designed so that they change in diameter and width with increasing speed. The static diameter of about 92 cm increases to 150 cm, while the width shrinks from 46 cm to about 26 cm. This effect leads to a “variable transmission ratio” in terms of speed (distance covered per tire revolution). The sidewalls of the tires are designed in such a way that they “fold” as it were when you accelerate, as the rim of the wheel rotates faster than the tire and the sidewalls during initial acceleration. The resulting twist is called "wrapping". When the tire is wrapped to the maximum, the contact with the track is as long as possible and offers maximum traction. This phenomenon can be seen well in numerous super slow motion videos. As soon as the TF has left the start line, the tires quickly become higher and thus narrower, which leads to less contact with the track surface. At the beginning of this process there may be a so-called “tire shake”. The reason for this is that the tire does not detach itself from the twist, but rather “rolls over” itself in this state, shaking the car violently. US professional teams use a rear tire for 4 to 5 runs (about 2 kilometers). A series production car tire for the EU market has a mileage of around 25,000 to 50,000 km. A TF rear slick costs around US $ 500-600.

The front tires are 3 inches (7.6 cm) in diameter and mounted on 17 inch (43 cm) wheels. Tire pressures vary between 70 and 100 psi (4.8 to 6.8 bar). At takeoff, unlike the rear tires, they have a "quiet job" as they are often in the air for 60 feet or more. These tires are also certified up to 560 km / h and are typically used for around 20 runs or around 5 miles.

The tires are made from a very heat-resistant and hard-wearing rubber compound called "D2A". At the center of the tire, this mixture is about 0.20 inches (5.08 mm) thick. That is less than 1% of the total tire structure. The load-bearing structure is a fabric carcass, which consists mainly of nylon and ensures the required flexibility and deformability of the tire. Tire wear is measured through small holes in the rubber, which the team can use to estimate how thick the tread is and when a change is required.

Although “ tire warmers ” would be available for TF dragsters, burn-out has become the main method for increasing the temperature of rear slicks. The dragster drives through a small amount of water and then lets the tires spin, causing them to smoke. During this process, the temperature rises up to 120 ° C. The “high art” in the following is to keep the heat in the tire until the actual start by the driver with the help of his guide steer the car back in the own “hot” rubber tracks that he has just laid, and additional heat ( and traction) by scrubbing old "rubber compound" off of his tires and adding fresh rubber to the track for extra grip. After a run, the tire temperature can briefly be 160 ° C to 180 ° C, not because of the frictional heat during burn-out , but primarily because of the enormous flexing work (mechanical stress / deformation) of the tire.

Web links

Individual evidence

  1. ^ Wolfgang Weber: Driving dynamics in perfection 1st edition. Motorbuch Verlag, Stuttgart 2009, ISBN 978-3-613-03128-9 . P. 209
  2. ↑ https://www.continental-reifen.de/fahrrad/technologie/race
  3. ↑ a b c Dan Welberry: Top Fuel Dragster / Owner's Workshop Manual . Ed .: Haynes Publishing. Haynes Publishing, Somerset, UK 2014, ISBN 978-0-85733-265-3 , pp. 44-46 .
  4. ↑ a b c Hockenheim-Ring GmbH: Motodrom Insight / The official Hockenheimring magazine . Ed .: Hockenheim-Ring GmbH. Edition 2020. Hockenheim 2020, p. 23 .