2011 Lexus IS 350 Owners Manual - Page 183

2-4. Using other driving systems CAUTION n TRAC may not operate effectively when Directional control and power may not be achievable while driving on slippery road surfaces, even if the TRAC system is operating. Do not drive the vehicle in conditions where stability and power may be lost. n If hill-start assist control does not operate effectively (vehicles with an automatic transmission) Do not overly rely on the hill-start assist control. The hill-start assist control may not operate effectively on steep inclines and roads covered in ice. n When the VSC is activated The slip indicator light flashes. Always drive carefully. Reckless driving may cause an accident. Exercise particular care when the indicator light flashes. n When TRAC and VSC are off Be especially careful and drive at a speed appropriate to the road conditions. As these are systems to ensure vehicle stability and driving force, do not turn off TRAC and VSC unless necessary. n Replacing tires Make sure that all tires are of the specified size, brand, tread pattern and total load capacity. In addition, make sure that the tires are inflated to the recommended tire pressure level. The ABS, VSC and TRAC systems will not function correctly if different tires are fitted on the vehicle. Contact your Lexus dealer for further information when replacing tires or wheels. n Handling of tires and suspension Using tires with any kind of problem or modifying the suspension will affect the driving assist systems, and may cause the system to malfunction. 190