Tire Monitor System - Operational Characteristics
SI B 36 05 07Wheels and Tires
December 2007
Technical Service
SUBJECT
Tire Warning Light Illuminated due to Low Ambient Temperature
MODEL
E90, E91 (3 Series) from 3/07
E92, E93 (3 Series)
E60 (5 Series) except M5 from 3/06
E60 (M5) from 9/06
E63, E64 (6 Series) from 3/06 except M6
E63, E64 (M6) from 9/06
E65, E66 (7 Series) from 3/06
E70 (X5)
E83 (X3) from 3/06
E85, E86 (Z4) from 1/06
INFORMATION
The Tire Pressure Monitoring System utilizes a warning lamp, located in the instrument cluster, to alert the driver of low tire pressure conditions. The warning is illuminated when the tire pressure decreases by approximately 25 percent. Temperature fluctuations can cause changes in tire pressure. For every 10° F change in ambient temperature, the tire pressure can change by 1 psi. Therefore, the tire warning indicator may be triggered due to a large change in temperature combined with a pre-existing low pressure condition.
When addressing customer concerns related to Tire Pressure Monitoring Systems, the following points should be noted:
^ Tire Pressure Monitoring Systems have been mandated by the Federal Government
^ The thresholds necessary to illuminate the tire warning lamp are consistent with Federal Guidelines
^ Driving on a significantly under-inflated tire causes the tire to overheat and can lead to tire failure
^ Under-inflation reduces fuel efficiency and tire tread life, and may affect the vehicle's handling and stopping ability
^ Customers should be advised to inspect their tires for physical damage and check the tire pressures when the tire warning is illuminated
^ The use of Tire Pressure Monitor Systems does not eliminate the need for routine maintenance by the vehicle operator.
^ BMW recommends checking tire inflation pressures every two weeks and before long trips
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