Classification of Pneumatic Tires

Pneumatic tires support the vehicle's weight through air pressure inside the tire, while also utilizing the elasticity of compressed air to provide shock absorption. They are standard equipment on over 99% of modern vehicles (including sedans, trucks, and new energy vehicles). Pneumatic tires can be further subdivided based on differences in structure, pressure, cord arrangement, and tread pattern, each tailored to specific usage requirements.

By Component Structure: Tubeless vs. Tubeless

Tubeless tires consist of a tube, an inner tube, and a fender. The inner tube is the core component for sealing air, while the fender acts as a cushion between the tire and the rim to prevent abrasion. These tires offer advantages such as low cost and easy maintenance. A puncture requires only a replacement tube, and the tire can continue to operate.

Therefore, they are widely used in low-speed trucks, construction vehicles, and other vehicles with low-speed requirements. However, tubeless tires also have significant disadvantages: friction between the inner tube and outer tube can generate heat, posing a risk of blowouts at high speeds. They also offer poor airtightness, requiring regular inflation, making them difficult to meet the high safety and reliability requirements of modern vehicles.

Tubeless tires (vacuum tires): Eliminating the inner tube, the seal is achieved directly through an airtight layer (usually made of butyl rubber) inside the outer tube. A sealing groove is designed at the junction of the outer tube and rim to ensure stable air pressure. 

Tubeless tires offer significant advantages: First, they offer enhanced safety. After a puncture, the air pressure slowly drops, preventing the instantaneous burst of tube-type tires, giving drivers ample time to respond. Second, they offer excellent heat dissipation.

The lack of friction between the inner tube and the outer tube effectively reduces tire temperature at high speeds, extending tire life. Third, they are easy to maintain, eliminating the need for frequent refills. Their lighter weight helps reduce vehicle fuel consumption. Currently, tubeless tires have become standard equipment for sedans, SUVs, and high-end trucks, with only some older, low-speed vehicles still using tube-type tires.

By operating pressure: Suitable for high-pressure, low-pressure, and ultra-low-pressure scenarios

High-pressure tires typically have an internal pressure between 1.5 and 4.5 MPa. They have a harder carcass and offer greater load-bearing capacity, but also offer poor shock absorption and reduced comfort. Early trucks and tractors mostly used high-pressure tires, but these had significant drawbacks and have been gradually replaced by low-pressure tires, now used only on a limited number of specialized engineering vehicles.

Low-pressure tires: With an internal pressure between 0.15 and 0.45 MPa, they are the choice for mainstream vehicles. Low-pressure tires have a flexible carcass that conforms better to the road, improving grip and comfort. They also provide a larger contact area with the tread, distributing pressure and reducing tread wear. Low-pressure tire pressures for passenger cars are typically between 0.22 and 0.25 MPa, while trucks, due to their higher load requirements, typically have pressures between 0.3 and 0.45 MPa.

Ultra-low-pressure tires: With an internal pressure below 0.15 MPa, they have an extremely soft carcass and a large contact area with the tread, effectively reducing ground pressure and making them suitable for driving on soft surfaces. This type of tire is primarily used for specialized vehicles such as off-road vehicles, dune buggies, and swamp buggies. For example, the ultra-low-pressure tires used on off-road vehicles can prevent the vehicle from sinking on muddy or desert roads by increasing the contact patch. The deep tread design also enhances grip on soft surfaces.

3. Cord Arrangement: A Technological Upgrade Between Bias and Radial Tires

Regular bias tires: The carcass cords are arranged in a cross pattern, forming an angle of approximately 45° with the tread centerline, with the cord layers interlaced. The advantages of regular bias tires include a simple structure, low cost, high sidewall strength, and excellent impact resistance, making them suitable for driving on rough roads.

Therefore, early trucks and agricultural vehicles often used this type of tire. However, regular bias tires also have significant disadvantages: high rolling resistance and fuel consumption; severe carcass heat generation, which can lead to aging at high speeds; and poor wear resistance, resulting in a short service life of typically only 30,000 to 50,000 kilometers.

Belted bias tires: These tires are based on standard bias tires but feature one or more additional belt layers (made of high-strength fiber or steel wire). These layers form a narrow angle (approximately 15°-20°) with the tread centerline, effectively limiting lateral deformation and improving tread rigidity and wear resistance. Belted bias tires offer performance intermediate between standard bias and radial tires, with rolling resistance 10%-15% lower and service life approximately 20% longer. They are primarily used in trucks and buses with moderate performance requirements.

Radial tires: The carcass cords are perpendicular to the tread centerline (forming a "meridian" pattern), and the cord layers do not cross. A high-strength belt layer (mostly steel belt) is located beneath the tread.

The structural design of radial tires offers numerous advantages: First, they offer low rolling resistance, 20%-30% lower than conventional bias tires, significantly reducing fuel consumption and making them suitable for new energy vehicles and economy-focused sedans. Second, they offer excellent wear resistance, high tread rigidity, and a uniform contact patch, resulting in a service life of 60,000-100,000 kilometers. 

Third, they offer excellent handling, with the belt layer effectively transmitting steering forces, resulting in faster steering response and greater stability at high speeds. Currently, radial tires have become the mainstream choice for sedans, SUVs, and high-end trucks, with a market share exceeding 90%.