These [summer] tire types have been optimized for specific performance attributes and as a result have special considerations that need to be understood and followed. It is important that the dealership identify these tires to its customers and provide proper counsel to them on usage and limitations consistent with this bulletin.
SUMMER TIRES
High Performance Summer Tires
Many General Motors high performance models come factory equipped with tires that are optimized for maximum dry and wet road performance while still retaining satisfactory tread life, excellent durability and low noise levels. In winter climates where snowfall may occur these tires may be found to provide less traction. Winter tires are a viable alternative that may greatly enhance winter driving.
Cold Weather Operation
Important: Customers need to know that their vehicle is equipped with a high performance summer tire that will have reduced traction performance at temperatures below approximately 5°C (40°F). It is recommended that suitable winter tires (if available) be installed below this temperature. All of these tires are not intended to be driven on snow or icy road surfaces. The rubber used in these tires loses flexibility and may develop surface cracks in the tire tread/shoulder area at colder temperatures. Refer to the photos below for examples.
Important: While the cracking will not result in air loss, it is damaging to the tire. Tires that have been used in cold climates and exhibit tread cracks should be discarded. This is not a warrantable item if the customer has driven the car in temperatures below approximately 5°C (40°F).
Surface cracks are cosmetic and will not result in a loss of air, however special tread and compounds used on these performance tires will cause a decrease in performance in cold climates. Driving with high performance summer tires on snow, ice or cold road surfaces may cause loss of control.
Refer to the latest version of Corporate Bulletin Number 04-03-10-013: Driving Characteristics of Rear Wheel Drive Vehicles and Available Winter Tires for further information on available replacement winter tires for cold climate operation. Additionally, dealers in the United States may call the GM Tire Program at 877-728-4737 for help with late season tire availability or substitutions.
Competition Oriented Summer Tires
Competition oriented tires are DOT approved for street use, but primary use would for track events and competitive driving. Competition oriented tires use a special tread pattern and compound that provide more grip than normal road tires. The minimum tread depth will be reached earlier than typical tires, resulting in reduced tire life. This special tread pattern and compound will have decreased performance in cold climates, heavy rain, and standing water. It is recommended that winter tires be installed on the vehicle when driving at temperatures below approximately 10°C (50°F) or on ice or snow covered roads. See Corporate Bulletin Number 04-03-10-013 for additional information on winter tires.
Important: Driving on wet roads, in heavy rain, or through standing water with competition oriented tires may cause hydroplaning and loss of control. Use extreme caution and drive slowly on wet roads. Driving with competition oriented tires on snow, ice, or cold road surfaces can cause loss of control or an accident. Competition oriented tires are summer season tires and are not intended to be driven on snow, ice, or road surfaces below 10°C (50°F). Do not drive a vehicle equipped with competition oriented tires in these conditions.
Important: Track courses put high loads on tires operating at high speed, which can lead to tire failure if not inflated properly. Refer customer to the vehicle specific owner’s manual for specific information on track usage.
Cold Weather Operation
Important: Competition oriented tires have rubber compounds that lose flexibility and may develop surface cracks in the tread area at temperatures below -7° C (20° F). Always store competition oriented tires indoors and at temperatures above -7° C (20° F) when not in use. If the tires have been subjected to -7°C (20°F) or less, let them warm up in a heated space to at least 10°C (50°F) for 24 hours or more before being installed or driving a vehicle on which they are installed. Do not apply heat or blow heated air directly on the tires. Always inspect tires before use.
