Motorcycle tires
The motorcycle tire is a pneumatic tire that is made from natural or synthetic rubber and various carcass materials as reinforcements. The most obvious difference to tires for multi-lane vehicles is the rounded contour of the tread to enable cornering in an inclined position.
The relevant set of rules is UN / ECE regulation No. 75 pneumatic tires for motorcycles and mopeds .
tasks
Motorcycle tires establish contact between the vehicle and the roadway and, on the one hand, have a major influence on driving dynamics and, on the other hand, are an essential element of driving safety. The tires must transmit braking, acceleration and cornering forces. Furthermore, they ensure driving comfort and dampen interferences that act on the vehicle from outside or that arise within the vehicle .
The front tire has to absorb more braking forces, while the rear tire has to absorb drive forces or acceleration forces.
When braking, the wheel contact forces of a motorcycle are shifted much more to the front axle than with a car due to the higher center of gravity , so that the majority of the braking forces are transferred there, even 100% when the rear wheel is lifted.
When accelerating, on the other hand, the wheel loads are shifted to the rear, so that the rear wheel, which transmits the engine power, is more heavily loaded. The fact that a wider tire is usually used at the rear than at the front is due to the fact that, for a fluid driving style, acceleration is also sought in an inclined position (driving out of curves “on pull”) and the greater cornering force is advantageous. Braking in an inclined position is only possible to a very limited extent.
For geometric reasons, a wider tire requires a higher lean angle at the same cornering speed, so that a narrower tire can ultimately be advantageous from a driving dynamics perspective. Likewise, wider front tires cause a greater righting moment when braking in an inclined position, since the contact point at which the braking force acts is relatively further to the side from the center axis of the front wheel suspension than with a narrower front wheel. In practice, tire widths of approx. 120 mm at the front and approx. 180 to 200 mm at the rear (on 17-inch rims) have become popular in the sports sector in recent years. Rear tires with a width of up to 300 mm are available for custom bikes . The largest currently offered tire is the Vee Rubber VRM302 360/30 R18 from Thailand with a width of 360 mm.
Construction types and tire types
Types of tires
Similar to car tires, motorcycle tires are usually of the type of diagonal tire (code “-”, “bias tire” ), but more recently also in the mixed form of diagonal radial tire (code letter “B”, “bias belted” ) and radial tire (Code letter "R").
UN / ECE regulation No. 75 defines these types as follows:
- Bias-ply tires are "tires whose cord plies extend from bead to bead and are arranged alternately at angles substantially less than 90 ° to the center line of the tread";
- Belted diagonal tires are "tires whose carcass is enclosed by a belt consisting of two or more plies of essentially inextensible cord arranged alternately at angles similar to those of the carcass ";
- Radial tires are “tires whose cord plies extend essentially at an angle of 90 ° to the center line of the tread from bead to bead and whose carcass is stabilized by an essentially inextensible circumferential belt”.
Deviating from this, there have been so-called 0-degree radial tires for some time . They contain a layer whose reinforcements (e.g. steel wires or nylon cords) run in the circumferential direction. This position of the fibers is intended to ensure a larger contact surface, less height growth of the tire at high speeds and greater running stability. This should also reduce the tire's own weight and its heating during operation.
The bead - i.e. the inner ring of the tire flanks - ensures that the tire sits securely on the rim. The bead contains one or more wire cores with the carcass threads wrapped around them. The rubber apex sits above the bead core. In this way, tire deformations can be structurally influenced when lateral forces occur, which affect the steering response and suspension comfort.
Tires for smaller two-wheelers (and for those with classic spoked wheels) are often tube designs with an internal air tube (code letter "TT", "Tube-Type" ), larger dimensions on cast wheels are mostly tubeless designs (code letter "TL", "Tubeless" ).
Tire types
The wide range of uses of motorcycles is reflected in the types of tires offered. This means that the construction of the tires is adapted to their respective use, for example through a special profile design or rubber compound. The range extends from tires for scooters , for off-road use in motocross , enduro sports or trials with more or less pronounced stud profiles to more moderate off-road / road mixed profiles for travel enduros or scramblers and touring or sport tires for road machines to treadless slick tires for racing.
Profiling and functioning
The adhesion of road tires - at least on a dry, clean road surface - arises almost exclusively from the static friction of the tread rubber mixture with the more or less rough road surface within the tire contact area. The macro-roughness of the covering with a roughness depth of 0.1 to 10 mm is more decisive for the dry adhesion, while the micro-roughness in the range between 0.001 and 0.1 mm has a greater influence on the wet adhesion. For this static friction to occur - at least in dry conditions - the presence of a tire tread is fundamentally of secondary importance. However, this is necessary in wet conditions (draining water from the contact area) and has other tasks such as a defined deformation of the tire contour in an inclined position or the control of tire heating by flexing (see the following section rubber compound and temperature ).
In the case of off-road tires for loose ground, on the other hand, the profile is predominantly decisive, since the more or less coarse tread blocks or studs have to be pressed into the soft ground in order to produce the necessary interlocking. When driving in muddy terrain, the question of self-cleaning of the profile is also relevant, since the mud has to be thrown out of the profile by the rotation of the wheel so as not to “smear” the cleats. However, pure off-road tires are less suitable for driving on the road, as the high negative proportion of the profile and deformation or even bending of the high lugs on asphalt prevent maximum grip. For this mixed use there are special enduro tires, which represent a compromise of roadworthy positive tread surfaces with more or less pronounced tread indentations for light off-road use.
The strongest form interlocking with the ground is achieved by studded tires in the ice speedway with their up to 28 mm long steel spikes, with which the greatest inclines in motorcycle racing can be achieved.
Gilstern refers to the processing of motorcycle tires with a suitable tool, the Gilster plane , which is no longer common today. Incised fine grooves, similar to the sipes of a car winter tire, should improve road grip in rain and snow.
Rubber compound and temperature
Basically, softer rubber compounds adhere better than harder ones, but are subject to greater wear and tear and lower mileage. Some manufacturers also use different compounds in the different zones of the tread: softer outer areas on the shoulders for high lean angle adhesion and a harder central area for the central part of the tread, which is more stressed when driving straight ahead, in order to achieve higher mileage and more even wear of the contour.
However, the relative coefficient of adhesion of the tread rubber mixture is - in addition to its chemical composition - dependent to a large extent on its temperature. If the rubber is too cold, it does not achieve the necessary elasticity to interlock with the roughness of the road surface. It is therefore important that the manufacturer selects the formulation of the tread in such a way that the compound achieves its maximum adhesion during the tire temperature reached during normal, intended use. The tires heat up by flexing and slip friction depending on driving to different degrees, and the basic hardness of the rubber composition has no influence (in principle harder rubber heats up more strongly by flexing). As a rough guide, normal road touring tires can be expected to have sufficient grip from a tread temperature of 20–25 ° C; the maximum grip is reached at around 35–60 ° C. Sports or racing tires require higher temperatures for this; these start at 65 ° C and reach up to 100 ° C during operation.
If the tire temperature is too low, for example in city traffic, when driving cautiously or shortly after starting the journey, the tire only achieves comparatively little grip. On the other hand, a touring tire that is well suited for standard or everyday use because of its warm-up behavior and quickly offers reliable grip can get so hot when driving hard or on the racetrack that the temperature window is exceeded and the attainable grip rapidly by "smearing" the overheated Rubber or tread damage and the tire wears out extremely quickly or is permanently damaged. A contrary example would be the use of a - supposedly better adhesive - soft super sports tire on a normally driven everyday vehicle, which, however, cannot bring its advantages to bear due to the minimum operating temperature that is difficult to achieve and even harbors a risk due to the constantly too cold condition.
Tires with a pure racing compound or even slicks represent an extreme, which must be brought to approx. 60-80 ° C by means of heated tire blankets in good time before the start of the journey , as this temperature - even on closed racetracks - can only be achieved by warming up and with an increased risk of falling can. Tires of this type are usually not approved for use on public roads.
Because of these interrelationships, when buying tires, the user must be careful to select a tire that is compatible with his / her usage profile in terms of the mixture and design. It should also always be noted that not only racing tires but also modern standard tires only achieve their maximum grip, especially at low outside temperatures, after a certain warm-up stretch.
Tire dimension
A motorcycle tire is determined by the following information:
- Tire width in millimeters or inches
- Ratio of cross-section to width in percent
- Construction - diagonal or radial
- Rim diameter in inches
- Load index
- Speed index
- possibly direction of travel
This information is usually permanently vulcanized onto the sidewalls of the tire.
Current names
The label 160 / 60ZR17 (69W) TL M / C means the following:
- 160 means the motorcycle tire is 160 mm wide
- 60 indicates the percentage ratio of tire cross-section to tire width, in our example that is 96 mm.
- ZR radial tires for Vmax over 240 km / h
- 17 indicates the rim diameter in inches .
- 69W Load index 69 (325 kg), which indicates the maximum permissible wheel load, speed index W means 270 km / h (Note: According to ECE-R75, the entire wheel load may not be used with full use of the speed index, it is above 240 km / h percentage discounts must be taken into account.). The indices in brackets mean that the tire is also suitable for even higher speeds outside the standard specification, but this must be certified by the manufacturer for the specific application.
- TL is an abbreviation for tubeless and means tubeless.
- M / C stands for motorcycle (mandatory identifier for America). This marking must also be applied to motorcycle and scooter tires in 13 to 19 inches since May 2003 at the latest.
The label 130 / 80-18 69S TT indicates a bias tire and here:
- The hyphen - (instead of ZR) indicates a diagonal construction.
- TT Tube Type, tire with tube
- S Speed symbol , here 180 km / h
- other information see above.
| class | A1 | A2 | A3 | A4 | A5 | A6 | A7 | A8 | B. | C. | D. | E. | F. | G | J | K |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| km / h | 5 | 10 | 15th | 20th | 25th | 30th | 35 | 40 | 50 | 60 | 65 | 70 | 80 | 90 | 100 | 110 |
| class | L. | M. | N | P | Q | R. | S. | T | U | H | V | VR | W. | ZR | Y | (Y) |
| km / h | 120 | 130 | 140 | 150 | 160 | 170 | 180 | 190 | 200 | 210 | 240 | > 210 | 270 | > 240 | 300 | > 300 |
If a direction of rotation is indicated by arrows on the side wall of the tire, the wheel must rotate in the direction of the arrow when driving.
Alphanumeric size designation
In North America there are still alphanumeric size designations ( "Harley sizes" ) for cross-ply tires, the metric equivalent of which can be found in a reference table . The tire dimension is specified in a letter combination consisting of an "M" for motorcycle and a code letter for the tire width, followed by a number for the aspect ratio and the rim diameter.
Example:
- The tire dimension MR 90-17 means that it is a motorcycle tire M , which is approx. 130 mm wide according to the code letter R and has a cross-section ratio of 90 % and a rim diameter of 17 inches. With the same aspect ratio, this roughly corresponds to the metric size 130 / 90-17 or the old inch size 4.50-17 .
Since the official coding ends with the dimension MV 85 , which corresponds to a width of approx. 150 mm, but current models consistently have wider tires, this designation system is largely obsolete. In recent times, the internationally common metric designation system has also predominantly been used for US two-wheelers and tires. In UN / ECE regulation No. 75 these designations are listed in Appendix 5 - Table 7 "Sizes and dimensions of American tires".
Old names
Example:
- Front: 3.25 S19
- Rear: 4.00 S18
The first number indicates the tire width in inches for diagonal tires . For radial tires, this information is in mm. The letter stands for the permitted speed range and the number behind it stands for the tire inner diameter from bead to bead.
Tire binding
In Germany, the tire designations of the installed tires must match the data in the registration certificate part 1 (formerly vehicle registration document). If necessary, a specific combination of front and rear tires must be observed.
For some motorcycles, the manufacturer and model designation of the tires to be used are precisely specified. In order to be a little more free in the choice of tires, or if the originally registered tire types are no longer available, this tire binding can be "unsubscribed". If there is no manufacturer entry, you can choose between different makes, only the tire dimensions have to be taken into account.
Another possibility is the release certificate (clearance certificate, UBB) from a tire manufacturer. The tires named therein for the respective motorcycle type can be fitted. The release certificate expands the list in the vehicle registration document without any bureaucratic effort, i.e. an individual acceptance according to Section 19 (2) StVZO is not required. They are available from tire dealers or manufacturers, today mostly by downloading them from their website.
Air pressure
The vehicle manufacturers prescribe the exact tire pressure for each vehicle type . This influences driving behavior and thus driving safety as well as tire service life. The load capacity of the tire depends on the air pressure. For this reason, this is specified by some manufacturers for the minimally loaded (= one-person operation) and the fully loaded vehicle, while other manufacturers stipulate a uniform tire pressure for all load conditions. This information can be found in the motorcycle owner's manual or in the tire manufacturer's recommendations for the respective motorcycle type. The tire manufacturers publish so-called tire manuals for this purpose.
In off-road use, especially in trials, the tire pressure is very low (in places below 0.5 bar) in order to increase the tire contact area. In order to prevent the tire cover from moving or slipping on the tube rim and thereby damaging the tube, one or more tire holders are used per wheel, which press the tire wall from the inside to the rim flange with a thread pull from the rim side.
Tread depth
The tire tread depth in Germany and Switzerland must be at least 1.6 mm (corresponds to 2/32 inches), otherwise the tire must be replaced. In order to make the remaining tread that is shrinking more visible, small elevations are incorporated into some tread grooves in the groove base, the so-called TWIs = tread wear indicator . For most motorcycle tires, however, the TWIs only show a remaining tread depth of just 0.8 mm, as this corresponds to an American standard height.
In Germany, motorcyclists with a tread depth of less than 1.6 mm have fallen below the legal limit ( Section 36 (2 ) StVZO ) and can expect a fine and 1 point in the register of fitness to drive .
For bicycles with an auxiliary motor , mopeds and light motorcycles , a tread depth of at least 1 mm is sufficient.
Mileage
The mileage is the distance that a tire covers from the new condition to the necessary replacement (usually due to wear). With road tires, a change is necessary at the latest when the minimum tread depth is reached - colloquially, the tire is then "worn out". In the case of off-road tires, the point at which the tire no longer adequately fulfills its purpose can be reached before the legal minimum tread depth is reached.
With motorcycle tires, the mileage that can be achieved depends on many factors, including:
- Tire manufacturer
- Tire type (sport, sport touring, enduro)
- individual driving style - frequent acceleration and braking increases wear
- Speed - at very high speeds, wear increases
- Tire pressure - if the tire pressure is incorrect, wear increases
- Weight (payload)
The material mixtures used are essential for the mileage. One speaks of "soft" for tires with greater grip and higher wear and "hard" for tires with less grip and less wear.
The tire manufacturers offer specially tailored tires for the various areas of application (race track, sport, tours, enduro). Depending on the intended use, the mileages that can be achieved are very different. A soft tire especially for the racetrack should have the best possible grip, but often has to be changed after a few 100 km. A harder touring tire still has good grip, but can reach 10,000 km and more.
Age
The calendar life of a tire is also limited. The tire manufacturers recommend replacing a tire that is five to six years old, even if there is still some tread left. A tire also ages when it is stationary, as the rubber hardens or becomes brittle. The so-called DOT number has also been vulcanized onto the sidewall of the tire since the 1980s . The former three-digit and now four-digit number shows the week of production and the year of production. For tires from the year 2000 onwards, the designation always has four digits, for example 2203 = 22nd production week of 2003. The production week can differ by one week from the calendar week of the respective year.
Handling new tires
New motorcycle tires must be run in before they can be used to their full extent. New motorcycle tires are covered with a sealing layer and adhering residues of the release agent from the vulcanizing mold, which must first be removed by carefully running in. By gradually increasing the angle of inclination in the curves, the outer tread of the tire contour is gradually roughened. It can take up to 200 kilometers to drive in.
Manufacturer
Selection of manufacturers:
- Avon
- Bridgestone
- Continental
- Dunlop
- Maxxis
- Mefo
- Metzeler
- Michelin
- Mitas
- Pirelli
- Heidenau tire factory
- swallow
See also
Web links
- Grip - Publication by the Institute for Bicycle Safety eV, Essen , on basic facts about road adhesion of motorcycle tires, PDF file, accessed on May 2, 2016
- Regulation No. 75 of the Economic Commission for Europe of the United Nations (UN / ECE) - Uniform Conditions for the Approval of Pneumatic Tires for Motorcycles and Mopeds - UN / ECE R-75 , accessed on May 2, 2016
Individual evidence
- ↑ How does the tire width affect the driving behavior? , Motorradonline.de, accessed November 22, 2015
- ↑ Wide tires without end? , Fahrtipps.de; accessed November 22, 2015
- ↑ motorradonline.de: 360 monster tires - and that drives! , accessed September 12, 2016
- ↑ An overview of the tires - Töff Magazin Schweiz. In: Töff Magazin. February 13, 2017, accessed February 23, 2018 .
- ↑ Radial tires with a 0-degree belt - motorcycle tires. In: motorradonline.de. February 25, 2003, accessed February 8, 2018 .
- ↑ Everything about grip and liability - how grip is created , motorradonline.de, accessed on May 15, 2016
- ↑ Hot glue - Regardless of whether touring tires or sports rubber - motorcycle tires only build reliable grip when the temperature is right ( memento of the original from May 1, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , motorradonline.de, accessed on May 1, 2016
- ↑ Guide to the grip of motorcycles , advice page from reifen-pneus-online.de, accessed on May 1, 2016
- ↑ The various tire types for motorcycles , advice page from reifen-pneus-online.de, accessed on May 1, 2016
- ↑ Metzeler Technical Handbook 2016, Metzeler Comparative Chart for Metric-Decimal Size Description , page 300 ( Memento of the original from May 2, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , E-booklet, accessed May 1, 2016
- ↑ Tire Desigantions - How To Read A Motorcycle Tire , AMA online publication , English, accessed on May 2, 2016
- ↑ Motorcycle tires: Approvals and declarations of no objection , detailed information from ADAC vehicle technology, status 05/2015 ( Memento of the original from May 2, 2016 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. , PDF file, accessed May 2, 2016
- ^ Website of the Metzeler company, Section Driving Safety - Minimum Profile , accessed on May 1, 2016
- ↑ Handling new tires. Motorcycle tire guide, accessed November 12, 2014 .
