Motorcycle tyres
Encyclopedia
Contact patch
Contact patch is the portion of a vehicle's tire that is in actual contact with the road surface. It is most commonly used in the discussion of pneumatic tires, , where the term is strictly used to describe the portion of the tire’s tread that touches the road surface...
under normal conditions, and so have a very large influence over motorcycle
Motorcycle
A motorcycle is a single-track, two-wheeled motor vehicle. Motorcycles vary considerably depending on the task for which they are designed, such as long distance travel, navigating congested urban traffic, cruising, sport and racing, or off-road conditions.Motorcycles are one of the most...
handling characteristics
Bicycle and motorcycle dynamics
Bicycle and motorcycle dynamics is the science of the motion of bicycles and motorcycles and their components, due to the forces acting on them. Dynamics is a branch of classical mechanics, which in turn is a branch of physics. Bike motions of interest include balancing, steering, braking,...
. Motorcycle tyres have a round cross section to facilitate the leaning necessary when a motorcycle turns. The unworn portion of tyre near the outer edge may be referred to as .
Motorcycles mainly use pneumatic tyres. However, in some cases where punctures are common (some enduro
Enduro
Enduro is a form of motorcycle sport run on courses that are predominantly off-road. Enduro consists of many different obstacles and challenges...
s), the tyres are filled with a "mousse" which is unpunctureable. Both types of tyre come in many configurations.
Types
Motorcycle tyres are available for many different applications, including: Sport, Sport Touring, Touring, Cruiser, ScooterScooter (motorcycle)
A scooter is a motorcycle with step-through frame and a platform for the operator's feet. Elements of scooter design have been present in some of the earliest motorcycles, and motorcycles identifiable as scooters have been made from 1914 or earlier...
, On/Off Road
Off-roading
Off-roading is a term for driving a vehicle on unsurfaced roads or tracks, made of materials such as sand, gravel, riverbeds, mud, snow, rocks, and other natural terrain.-Off-road vehicle:...
, Dual-Sport, Enduro
Enduro
Enduro is a form of motorcycle sport run on courses that are predominantly off-road. Enduro consists of many different obstacles and challenges...
, Motocross
Motocross
Motocross is a form of motorcycle sport or all-terrain vehicle racing held on enclosed off road circuits. It evolved from trials, and was called scrambles, and later motocross, combining the French moto with cross-country...
and Racing
Motorcycle racing
Motorcycle sport is a broad field that encompasses all sporting aspects of motorcycling. The disciplines are not all "races" or timed-speed events, as several disciplines test a competitor's various riding skills.-Motorcycle racing:...
. There are tyres designed for dirtbikes, touring, sport and cruiser bikes.
Sport/performance tyres provide amazing grip but may last 1,000 miles (1,600 km) or less. Cruiser and "sport touring" tyres try to find the best compromise between grip and durability. There is also a type of tyre developed specifically for racing. These tyres offer the highest of levels of grip for cornering. Because of the high temperatures at which these tyres typically operate, use on the street is unsafe because the tyres will typically not reach optimum temperature before a rider arrives at the destination, thus providing almost no grip en route. In racing situations, racing tyres would normally be brought up to temperature in advance by the use of tyre warmers.
Sport Touring tyres are generally not used for high cornering loads, but for long straights, good for riding across the country.
Sport Street tyres are for aggressive street riders that spend most of their time carving corners on public roadways. These tyres do not have a long life, but in turn have better traction in high speed cornering. Street and sport street tyres have good traction even when cold, but when warmed too much, can actually lose traction as their internal temperature increases.
Track or Slick tyres are for track days or races. They may have more of a triangular profile, which in turn gives a larger contact patch while leaned over. These tyres are not recommended for the street by manufactures, and are known to have a shorter life on the street. Due to the triangulation of the tyre, there will be less contact patch in the centre, causing the tyre to develop a flat spot quicker when used to ride on straightaways for long periods of time and have no tread so they lose almost all grip in the wet. Racing slicks are always made of a softer rubber compound and do not provide as much traction as street tyres until warmed to a higher internal temperature than street tyres normally operate at. Most street riding will not put a sufficient amount of friction on the tyre to maintain the slick's optimal tyre temperature, especially in colder climates and in spring and fall.
Off road tyres have knobbly, deep treads for maximum grip on loose dirt, mud, sand, or gravel; such tyres tend to be less stable on paved surfaces.
Touring tyres are usually made of harder rubber for greater durability. They may last longer, but they tend to provide less outright grip than sports tyres at optimal operating temperature
Operating temperature
An operating temperature is the temperature at which an electrical or mechanical device operates. The device will operate effectively within a specified temperature range which varies based on the device function and application context, and ranges from the minimum operating temperature to the...
s. The tradeoff is that touring tyres typically offer more grip at lower temperatures, meaning they can be more suitable for riding in cold or winter conditions whereas a sport tyre may never reach the optimal operating temperature.
Properties
There are several properties of motorcycle tyres that influence the performance, handling, and stability of a motorcycle.- Rolling resistanceRolling resistanceRolling resistance, sometimes called rolling friction or rolling drag, is the resistance that occurs when a round object such as a ball or tire rolls on a flat surface, in steady velocity straight line motion. It is caused mainly by the deformation of the object, the deformation of the surface, or...
is the resistance that occurs when a tyre rolls on a flat surface. The rolling resistance coefficients of motorcycle tyres are about 0.02. It tends to increase with forward speed and decrease with inflation pressure.
- Cornering forceCornering forceCornering force or side force is the lateral force produced by a vehicle tire during cornering.Cornering force is generated by tire slip and is proportional to slip angle at low slip angles. The rate at which cornering force builds up is described by relaxation length...
is the lateral (i.e. parallel to the road surface) force produced by a vehicle tyre during cornering. Cornering force coefficients of motorcycle tyres tends to decrease with increased vertical load, increased inflation pressure, and increased temperature.
- Camber thrustCamber thrustCamber thrust and camber force are terms used to describe the force generated perpendicular to the direction of travel of a rolling tire due to its camber angle and finite contact patch...
is the force generated perpendicular to the direction of travel of a rolling tyre due to its camber angleCamber anglethumb|100px|From the front of the car, a right wheel with a negative camber angleCamber angle is the angle made by the wheels of a vehicle; specifically, it is the angle between the vertical axis of the wheels used for steering and the vertical axis of the vehicle when viewed from the front or...
and finite contact patchContact patchContact patch is the portion of a vehicle's tire that is in actual contact with the road surface. It is most commonly used in the discussion of pneumatic tires, , where the term is strictly used to describe the portion of the tire’s tread that touches the road surface...
.
- Pneumatic trailPneumatic trailPneumatic trail or trail of the tire is a trail-like effect generated by compliant tires rolling on a hard surface and subject to side loads, as in a turn...
is a trail-like effect generated by compliant tyres rolling on a hard surface and subject to side loads, as in a turn. It is the distance that the resultant cornering force of side-slipSlip angleIn vehicle dynamics, slip angle or sideslip angle is the angle between a rolling wheel's actual direction of travel and the direction towards which it is pointing...
occurs behind the geometric center of the contact patchContact patchContact patch is the portion of a vehicle's tire that is in actual contact with the road surface. It is most commonly used in the discussion of pneumatic tires, , where the term is strictly used to describe the portion of the tire’s tread that touches the road surface...
.
- Relaxation lengthRelaxation lengthRelaxation length is a dynamic property of pneumatic tires that describes the delay between when a slip angle is introduced and when the cornering force reaches its steady-state value....
describes the delay between when a slip angleSlip angleIn vehicle dynamics, slip angle or sideslip angle is the angle between a rolling wheel's actual direction of travel and the direction towards which it is pointing...
is introduced and when the cornering force reaches its steady-state value.
Speed and construction
As with four-wheeled vehicles, tyres for motorcycle have a tyre code, which describes a tyre's width, height/width aspect ratio, wheel diameter, load index and speed rating.The most common are:
- 3 digit number: The "nominal section width" of the tyre in millimetres; the widest point from both outer edges.
- /: Slash character for character separation.
- 2 or 3 digit number: The "aspect ratio" of the sidewall height to the total width of the tyre, as a percentage.
- An optional letter indicating construction of the fabric carcass of the tire:
- B: bias belt (where the sidewalls are the same material as the tread, leading to a rigid ride)
- D: diagonal
- R: radialRadial tireA radial tire is a particular design of automotive tire . In this design, the cord plies are arranged at 90 degrees to the direction of travel, or radially ....
- if omitted, then it is a cross ply tyre
- 2 digit number: Diameter in inches of the wheel that the tyre is designed to fit.
- 2 or 3 digit number: Load index; see table below
- 1 or 2 digit/letter combo: Speed rating; see table below
Load index
| LI | kg | LI | kg | LI | kg | LI | kg | LI | kg |
|---|---|---|---|---|---|---|---|---|---|
| 19 | 77,5 | 36 | 125,0 | 53 | 206 | 70 | 335,0 | 87 | 545,0 |
| 20 | 80,0 | 37 | 128,0 | 54 | 212,0 | 71 | 345,0 | 88 | 560,0 |
| 21 | 82,5 | 38 | 132,0 | 55 | 218,0 | 72 | 355,0 | 89 | 580,0 |
| 22 | 85,0 | 39 | 136,0 | 56 | 224,0 | 73 | 365,0 | 90 | 600,0 |
| 23 | 87,5 | 40 | 140,0 | 57 | 230,0 | 74 | 375,0 | 91 | 615,0 |
| 24 | 90,0 | 41 | 145,0 | 58 | 236,0 | 75 | 387,0 | 92 | 630,0 |
| 25 | 92,0 | 42 | 150,0 | 59 | 243,0 | 76 | 400,0 | 93 | 650,0 |
| 26 | 95,0 | 43 | 155,0 | 60 | 250,0 | 77 | 412,0 | 94 | 670,0 |
| 27 | 97,5 | 44 | 160,0 | 61 | 257,0 | 78 | 425,0 | 95 | 690,0 |
| 28 | 100,0 | 45 | 165,0 | 62 | 265,0 | 79 | 437,0 | 96 | 710,0 |
| 29 | 103,0 | 46 | 170,0 | 63 | 272,0 | 80 | 450,0 | 97 | 730,0 |
| 30 | 106,0 | 47 | 175,0 | 64 | 280,0 | 81 | 462,0 | 98 | 750,0 |
| 31 | 109,0 | 48 | 180,0 | 65 | 290,0 | 82 | 475,0 | 99 | 775,0 |
| 32 | 112,0 | 49 | 185,0 | 66 | 300,0 | 83 | 487,0 | 100 | 800,0 |
| 33 | 115,0 | 50 | 190,0 | 67 | 307,0 | 84 | 500,0 | - | - |
| 34 | 118,0 | 51 | 195,0 | 68 | 315,0 | 85 | 510 | - | - |
| 35 | 121,0 | 52 | 200,0 | 69 | 325 | 86 | 530,0 | - | - |
Speed rating
| Rating | Speed (km/h) | Speed (mph) |
|---|---|---|
| Moped | 50 | 30 |
| J | 100 | 62 |
| K | 110 | 69 |
| L | 120 | 75 |
| M | 130 | 81 |
| P (or-) | 150 | 95 |
| Q | 160 | 100 |
| R | 170 | 105 |
| S | 180 | 113 |
| T | 190 | 118 |
| U | 200 | 125 |
| H | 210 | 130 |
| V | 240 | 150 |
| W | 270 | 168 |
| ZR | over 240 | over 150 |