Motorcycle Tires (Chopper Tires)
There are several different types of motorcycle tires:
Touring (choppers and cruisers) - These motorcycle tires are generally not used for high cornering loads, but for long distances such as cross country.
Street (crotch rockets) - For sportbikes that are generally not going to be riding aggressively. Motorcycle riders of this type usually want tires that are going to last a few more miles.
Sport Street (fast crotch rockets) - These tires are for aggressive street riders that spend a lot of time carving corners on roadways. These tires do not have a long life when used this way, but they do have very good traction in high speed cornering.
Track/Slick Tires (racing) - These motorcycle tires are for track races. They are more triangular in shape which gives a larger contact area while leaning over. These tires are not recommended for street use by manufactures, and are known to have a shorter life on the street. Due to the triangulation of the tire, there will be less contact patch in the center, causing the tire to develop a flat spot quicker when used to ride on straight roads for long periods of time.
Bias tire construction utilizes body ply cords that extend diagonally from bead to bead, usually at angles in the range of 30 to 40 degrees, with successive plies laid at opposing angles forming a crisscross pattern to which the tread is applied. The design allows for the entire tire body to flex easily providing the main advantage of this construction, a smooth ride on rough surfaces. This cushioning characteristic makes for major disadvantages of a bias tires: increased rolling resistance and less control and traction at higher speeds.
Belted bias tire
A belted bias tire starts with two or more bias-plies to which stabilizer belts are bonded directly beneath the tread. This construction provides smoother ride that is similar to the bias tire, while lessening rolling resistance because the belts increase tread stiffness. However the plies and belts are at different angles, which lessens performance compared to radial tires.
Radial tire construction utilizes body ply cords extending from the beads and across the tread so that the cords are laid at approximately right angles to the centerline of the tread, and parallel to each other, as well as stiff stabilizer belts directly beneath the tread. The advantages of this construction include longer tread life, better steering control, and lower rolling resistance. A disadvantage of the radial tire is that it produces a harder ride at low speeds on rough roads.
Many tires used in industrial and commercial applications are non-pneumatic, and are manufactured from solid rubber and plastic compounds via molding operations. Solid tires include those used for lawn mowers, golf carts, scooters, and many types of light industrial vehicles, carts, and trailers. Solid (non-pneumatic) tires have also been designed for automotive use using special compounds of polyurethane, although have not yet been delivered for broad market use.
Tire performance metrics
Dry traction is measure of the tire’s ability to deliver traction, or grip, under dry conditions. Dry traction increases in proportion to the tread contact area. Dry traction is also a function of the tackiness of the rubber compound.
Wet traction is measure of the tire’s ability to deliver traction, or grip, under wet conditions. Wet traction is improved by the tread design’s ability to channel water out of the tire footprint and reduce hydroplaning.
Friction between the tire and the roadway causes the tread rubber to wear away over time. Government standards prescribe the minimum allowable tread depth for safe operation. There are several types of abnormal tread wear. Poor wheel alignment can cause excessive wear of the innermost or outermost ribs. Over inflation can cause excessive wear to the center of the tread. Under inflation can cause excessive wear to the outer ribs. Tire manufacturers and car companies have mutually established standards for tread wear testing that include measurement parameters for tread loss profile, lug count, and heel-toe wear. Also can be known as tire wear.
A tire rotating at high speed will develop a larger diameter due to centrifugal forces that force the tread rubber away from the axis of rotation. As the tire diameter grows the tire width decreases. This centrifugal growth can cause rubbing of the tire against the vehicle at high speeds. Motorcycle tires are often designed with reinforcements aimed at minimizing centrifugal growth.
Rolling resistance is the resistance to rolling caused by deformation of the tire in contact with the roadway. As the tire rolls, tread enters the contact area and is deformed flat to conform to the roadway. The energy required to make the deformation depends on the inflation pressure, rotating speed, and numerous physical properties of the tire structure, such as spring force and stiffness. Tire makers seek lower rolling resistance tire constructions in order to improve fuel economy in cars and especially trucks, where rolling resistance accounts for a high amount of fuel consumption.
The use of performance oriented tires, which have a tread pattern and rubber compounds designed to grip the road surface, usually has slightly shorter stopping distances. However, specific braking tests are necessary for data beyond generalizations.
The tire tread and sidewall elements undergo deformation and recovery as they enter and exit the footprint. Since the rubber is elastomeric, it is compressed during this cycle. As the rubber deforms and recovers it imparts cyclical forces into the vehicle. These variations are collectively referred to as Tire Uniformity. Tire Uniformity is characterized by Radial Force Variation (RFV), Lateral Force Variation (LFV), and Tangential Force Variation. Radial and Lateral Force Variation is measured on a Force Variation Machine at the end of the manufacturing process. Tires outside the specified limits for RFV and LFV are rejected. In addition, Tire Uniformity Machines are used to measure geometric parameters including Radial Runout, Lateral Runout, and Sidewall Bulge in the tire factory at the end of the manufacturing process as a quality check.
When a tire is rotated it will exert a centrifugal force characteristic of its center of gravity. This cyclical force is referred to as balance, or imbalance or unbalance. Tires are checked at the point of manufacture for excessive static imbalance and dynamic imbalance using automatic Tire Balance Machines. Tires are checked again in the auto assembly plant or tire retail shop after mounting the tire to the wheel. Assemblies that exhibit excessive imbalance are corrected by applying balance weights to the wheels to counteract the tire/wheel imbalance.
To facilitate proper balancing, most high performance tire manufacturers place red and yellow marks on the sidewalls of its tires to enable the best possible match-mounting of the tyre/wheel assembly. There are two methods of match-mounting high performance tire to wheel assemblies using these red (Uniformity) or yellow (Weight) marks.