2007 Lexus IS 250 Owners Manual - Page 166

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) The hill-start assist control may not operate effectively on steep inclines and roads covered in ice. n Replacing tires 2 When driving Make sure that all tires are of the same 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 and VSC 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. 153