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Home >> Porsche >> 2014 >> Cayenne S >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 59 (44 - Wheels, Tyres, Suspension Alignment (4.8L Turbo) -- 92A - Cayenne (92A)) >> Ti, 4440 ATI Front Tire Scrubbing (1304) >> Front Tire Scrubbing

Front Tire Scrubbing

WARNING: This page is about a different variant/trim than selected.

Vehicle Type: All 

Model Year: All 

Information: Tire scrubbing may occur at higher steering angles at low vehicle speed. This may result in a customer complaint of tire and front end noise. The customer may also complain of steering feedback concerns.

Work Procedure: Tire scrubbing is a lateral movement of the tire over the surface on which it rests. There are numerous factors involved in tire scrubbing, several are described below.

Steering geometry is designed so that for a given steering angle appropriate tire slip angles are produced. Tire slip angles are required so that necessary tire cornering forces will be generated as vehicle speed increases. Reducing slip angles will have the effect of reducing cornering forces and thus reducing vehicle handling capabilities.

Cold tires do not grip as well as warm tires. Cold tires also do not deform to absorb lateral loads as easily as warm tires. Tires with a low profile also do not deform as much as a tire with a higher profile. A cold low profile tire is more rigid than a warm high profile tire. So, cold, low profile tires can slip more easily than a warm, high profile tire.

Larger tires have a larger contact patch. More energy is used in turning a larger tire, so a higher steering load is the result. Larger contact patches mean that more energy from the higher steering loads will be released as a tire slips.

The amount of energy released is sufficient to create noise as the tire laterally scrubs over the road surface and as it moves through the suspension components.

The tire scrub may feel like a slight dragging of the tire due to the lateral movement of the tire over the road surface. This is a normal condition. No repairs are necessary.

Reference: Society of Automotive Engineers, Car Suspension and Handling, 4th edition