SST Tires, Structure And Labeling, Run-Flat Tire

A tire pressure monitoring display is necessary when using run-flat tires.

Tire damage and the pressure loss resulting from it is not always recognizable.

SST tires are identified with a special code (RSC = Run-flat System Component) on the side wall.

Fig 1: Locating RSC On Side Wall

Courtesy of AUDI

The identification on the side wall of run-flat tires can differ depending on the manufacturer.

Self-Supporting Tire stands for a tire system with emergency running characteristics in the event of a loss of pressure. In the event of a flat tire, the driver can continue driving to a limited extent to the next Service Information.

Advantage

SST tires make it possible to drive up to 50 km (31.1 miles) at a maximum of 80 km/h (49.7 mph) even with a complete loss of pressure.

Driving style, speed, road surface, weather conditions, tire condition and tire load influence the distance.

With SST tires, it is not necessary to immediately change a tire when it suffers from a complete loss of pressure (for example no tire changing in an area with low visibility or in dangerous conditions).

Braking, steering and driving performance remain for the most part even after the tire loses pressure.

A spare wheel is no longer necessary when using SST tires. From the view of the customer, this means: saving space and weight.

Assembly

Fig 2: Identifying Tire Structure

Courtesy of AUDI

1 -  Bead with Bead Core

2 -  Sidewall

3 -  Sidewall Reinforcement

4 -  Rim with extended hump (EH2) on both sides - required when using run-flat tires

Technology in Detail

Standard Tires without Emergency Running Characteristics

-- -I- standard tires with air.

Fig 3: Identifying Standard Tires With Air & Standard Tires Without Air

Courtesy of AUDI

-- -II- standard tires without air.

-- If the standard tire loses air, the rim presses the side wall together. The rubber in a flat tire is heated strongly and quickly loses its properties.

SST Tires with Reinforced Side Wall

The self-supporting, reinforced side walls from the basis of SST technology.

-- -I- SST tires with air.

Fig 4: Identifying SST Tires With Air And SST Tires Without Air

Courtesy of AUDI

-- -II- SST tires without air.

-- Especially thick side walls -A- support the empty tires on a standard rim and the vehicle remains maneuverable. A special rubber mixture reinforces the tires and supports the vehicle in an emergency.

The reinforced side walls, unlike a standard tire, prevent the tire flanks from pinching between the road and rim when flat.

Difference in Version H2 and EJ2 Extended Hump Rim

• The increased hump on the EH2 Extended Hump Rim prevents the SST tire from springing off when pressure is lost.
• EH2 Extended Hump Rim builds up toward the center of the wheel.