System for determining pneumatic tire pressure for motor vehicle by comparing actual to adequate wheel rotational speed

A system for determining a reduction in the pneumatic tire pressure of road wheels on a motor vehicle, comprising:

• first means for detecting an actual rotational speed difference between rotational speeds of rear left and right road wheels of the motor vehicle;
• second means for detecting an operating condition of the motor vehicle;
• third means for calculating an adequate rotational speed difference between rotational speeds of the rear left and right road wheels based on an output signal from said second means;
• and
• comparing means for comparing said adequate rotational speed difference calculated by said third means and said actual rotational speed difference detected by said first means, and determining a pneumatic tire pressure reduction when the difference between the compared actual and adequate rotational speed differences exceeds a predetermined value.

A system for determining a reduction in the pneumatic tire pressure of road wheels on a motor vehicle, comprising:

• first means for detecting rotational speeds of drive and non-drive road wheels of the motor vehicle and calculating an actual ratio of slippage between the drive and non-drive road wheels based on the detected rotational speeds;
• second means for calculating an adequate ratio of slippage of the drive road wheels if the pneumatic tire pressure of the drive and non-drive road wheels is determined as normal from an operating condition of an engine of the motor vehicle;
• and
• comparing means for comparing said actual ratio of slippage calculated by said first means and said adequate ratio of slippage calculated by said second means, and determining a pneumatic tire pressure reduction when the difference between the compared actual and adequate ratios of slippage exceeds a predetermined value.