Tires are flexible casings made of rubber covering the rim of a wheel. They cushion the wheels of a vehicle resulting in an enhanced surface grip. These products apply to a diverse range of moving objects, including automobiles, trucks, tractors, bicycles, motorcycles, buses, and other transport conveyances.
The most common tire structure today is pneumatic, supported by internal pressure. Robert Thomson, a Scottish engineer and inventor, is credited with the initial design of the pneumatic casing fitted with an inner tube in 1845. Current models rely on a pressure seal between the rim and the wheel to contain the compressed air.
Tire production advanced in the 20th century with the introduction of synthetic rubber by Bayer in the 1920s and
radial construction by Michelin in 1946. Today, a vast majority tires are radials due to their superiority in fuel efficiency and handling.
Tire production is divided into multiple categories according to structure and design, including:
Bias construction comprises diagonal layers made of body ply cord material extending between the beads at a 30-40 degree angle to the tread’s centerline. As a result, bias tires facilitate a smooth drive over rough surfaces. However, the technology leads to increase in rolling resistance and diminished traction and control at greater speeds. Limited commercial production exists for supplying collector vehicles.
Radial tire design incorporates a cord angle equating to approximately 90 degrees to the centerline. The body ply cords run parallel to each other and stabilizer belts located right beneath the tread. The belt overwrap positioned below the tread surface helps maintain structural stability. The radial structure decreases rolling resistance and promotes steering response at greater speeds. Radial casings offer longer tread life compared to earlier alternatives. A disadvantage is a bumpier ride at lower speeds on rugged terrain.
Tubeless tire construction was created to tackle the problem of flat tires. These tires have an inner lining instead of tubes. The lining consists of rubber with limited permeability to trap air inside the tire, preventing air leaks. As a result, the loss of air pressure from a perforated tire in motion is slowed down.
Solid tires are prominent in industrial conveyances. Many are non-pneumatic and consist of compounds derived from molding solid rubber or plastic. Such products are found in lawn mowers, golf carts, skateboards and industrial vehicles such as instance forklifts. Installation is executed via a hydraulic press.
Semi-pneumatic tires contain a hollow center and are not pressurized. Other characteristics include minimum weight, low cost, resistance to puncturing, and cushioning. Standard uses include lawnmowers, wheelchairs, and wheelbarrows. Industrial applications employ the rugged versions featuring a design that prevents the rims from pulling off.
Emergency tires serve as a temporary backup if a regular tire is unfit for use. They are smaller than normal tires, thereby saving storage space and reducing the overall vehicle weight.
Standard classification of wheel casings by function includes the following.
Passenger and light truck tires -- In addition to the regular structures, a selection of specialized options exists including:
High performance tires integrate soft rubber compounds that enhance traction and yield superior performance when cornering at an increased speeds. Diminished tread lifespan is a disadvantage.
Summer tires are ideal for seasons without snow. They are designed to reduce noise and facilitate smooth driving and handling at high speed.
All-weather tires have a greater number of tread kerfs than the summer version. These tires are suitable for areas with short snow seasons. They feature a mix of characteristics enabling driving on dry and wet roads in summer and snowy or icy roads during winter.
Winter tires have treads segmented into small blocks to improve steering and braking on snow-covered roads. The deeper grooves and rib pattern prevent slide slippage, and the lug design provides extra propulsion ability. Snow caught in the grooves forms snow pillars through up and down compression resulting in better steering and traction in soft snow.
Some winter casings are fabricated with metal studs to maximize traction for use in colder regions. The studs cut into the ice surface and cause damage to roads. By contrast, studless models comprise of hydrophilic or porous rubber materials that stick to wet and icy surfaces. This version offers a comparable performance in most conditions, except on polished ice.
All-terrain -- SUVs and light trucks rely on all-terrain models. They possess firmer sidewalls to avoid punctures when driven off-road. The tread patterns are developed with wider spacing keeping mud out of the treads.
Truck and bus tires -- Also called heavy-duty tires, these tires are used in such vehicles as commercial freight-carrying trucks, dump trucks, and buses. They are divided into groups based on vehicle position, including drive axle, steering or trailer. Particular reinforcements, materials, and tread parameters permit operation with heavier loads.
Off the road (OTR) tires -- Casings of this type are best suited for construction vehicles, including backhoes, graders and wheel loaders. The construction is either bias or radial. The bias structures are fabricated with numerous reinforcing plies enabling them to handle heavy loads and severe conditions.
Motorcycle tires -- Motorcycle tires feature the following options:
Sport touring tires are ideal for long, straight rides with medium cornering loads.
Sport street tires are designed for aggressive cornering at greater speeds. A shorter tread life offsets the traction advantage.
Track tires are optimized for racing. Their triangular form creates a larger point of surface contact. They have a shorter tread life than standard tires and are not suitable for street driving.
Aircraft -- Landing gear must withstand extreme loads over short intervals of time. More tires are needed as aircraft weight increases to distribute its weight. The construction supports stability in conditions with heavy crosswinds. The tread pattern inhibits hydroplaning and promotes braking performance. The tires are inflated with nitrogen as a means of limiting expansion and contraction due to drastic temperature and pressure fluctuations during flight.
Agricultural -- Farm vehicles, such as tractors and harvesters, employ the agricultural product category. Deep lugs with wide spaces in the tires result in an improved soil grip.
Tire production covers an extensive array of shapes and sizes based on the function and performance requirements. To select the right product, first determine if a particular classification is available for the application. When choosing from different brands, evaluate and compare the performance-related characteristics applicable to the products. Look into the manufacturer’s specifications to ensure the outlined parameters match the expectations.
Several specifications apply to tires, including:
Inflation pressure -- Tire manufacturers supply recommended levels of inflation pressure. Adherence to these levels allows for safe operation without exceeding the indicated load rating and loading capacity of the motor vehicle. The maximum pressure rating is imprinted on the tire.
Load rating -- Manufacturer’s load ratings stipulate the amount of weight a tire can support. Exceeding the levels can lead to difficulty in steering causing unsafe driving conditions.
Speed rating -- The rating identifies the maximum operational speed.
Service rating -- These specifications apply to the tires used on buses and trucks.
Treadwear rating -- The treadwear grade represents the manufacturer’s expectations as to a tire’s lifespan. The measurement compares the manufacturer’s product to a Course Monitoring Tire, the standard testing tire used for comparison purposes.