There are three main tyre contructions:
- » Bias ply (cross ply or diagonal ply)
- » Bias belted
- » Radial
Bias ply (cross ply) tyre construction
Bias ply tyre is known for its classical, conventional design. Simple structure of construction consists of only two elements, carcass and one or more plies.
The carcass makes the structure of a tyre body and it consists of several parts: tread, bead, sidewall, shoulder, and ply (plies). The ply is a layer made of textile cords coated into rubber. The layers are arranged diagonally, 30-45 degree angle (usually an angle of 45-degree) in relation to circumferential tyre centraline. Plies are set one on top of another, in alternate directions. Changing the angle of cord changes tyre performance. Lower angle (30 degrees for example), makes the tyre much stiffer, it generates more heat while it is used, The tyre is more stable at higher speeds, but the ride is uncomfortable. By increasing the cord angle from 45 degrees the ride will become more comfortable.
Bias tyre usually has 2 or 4 plies. The more plies the tire has, the stiffer it will be and heated more.
Bias tyres preceded radial tyres that are now commonly in use. Even today, many motorcycles are equiped with bias tyres as original equipment.
The reason for its long lasting is simple structure and impact resistance especially when it is used off-road (off road).
Engineered for maximum speed to 240 km / h.
Typical cross ply tyre designation:
4.00 - 18 M/C 64H
(-) - Bias tyres
(M/C) - Motorcycle tyre
Bias belted tyre construction
Next generation of bias tyres, radial tyres predecessors, are the bias-belted tyres. Their construction is very similar to previous except the fact that the carcass of bias-belted tyres are reinforced in tread area with two or more belts with crossed layers. The belt is made of steel or synthetic (rayon, nylon, or fiberglass) cords which gives strength to the tyre sidewalls and great stability to the tread. The more plies tyre has it will be able to bear more weight although contact patch will be smaller and the traction weaker.
The function of belt is to reduce dynamic deformation caused by centrifugal forces and to lower its operating temperature. The advantage is among others also reduced rolling resistance of stiffer tyres which provides more comfortable ride.
Carcass and belts are made with combination of different materials depending on different goals they have to reach.
Advantages of bias-belted construction make them good for heavy motorcycles.
Bias-belted tyres are generally more expensive than classical bias tyres, but they also last longer.
Typical bias-belted tyre designation:
150/70 B 17 M/C 69Q
(B) - Bias belted tyres
(M/C) - Motorcycle tyre
Radial tyre construction
The first radial tyre for road motorcycles was made in 1987 by Michelin. It was revolution in the world of motorcycles. Today, all road sport and supersport bikes are equiped with radial tyres.
In comparison with bias-belted tyre the structure of the radial tyre carcass is diferent, its cords run around the tyre from bead to bead radially. Plies do not cross over each other and tyre is able to flex. Casing angle is about 90° to the centraline and a belt angle of 0 - 25°. Two or more belts under the tread give the tyre stability and higher speeds are possible.
The belts are made of different materials such as rayon, nylon, fiberglass and steel (steel belted radial tyre), providing greater rigidity in the tread area and flexibility in the area of the sidewalls. Reduced thickness of the sidewalls affects less heating of tyres, lower risk of damage and increased tyre stiffness.
Radial tires are lighter, last longer, have better cornering grip, and provide lower rolling resistance. Due to the superior acceleration, braking and cornering radial tires are the best choice for fastest motorcycles.
Typical radial tyre designation:
190/50 ZR 17 M/C (73W)
(R) - Radial tyre