KPI – Static Camber

Static camber is a measure of the inclination of a tyre to the vertical in front view.  When the top of the tyre leans towards the centre of the vehicle a tyre is said to have negative camber, as shown in the diagram below.  A tyre has positive camber when the top of the tyre leans away from the centre line of the vehicle.

Tyre camber angle to the road surface is one of the key variables which influences tyre performance.  Static camber, bump camber, camber compliance and steering geometry all combine to give a resultant tyre camber to road under any driving scenario.

A tyre with camber will generate a lateral force known as camber thrust. The direction of camber thrust is the same as the direction that the top of the tyre is leaning. So for a static negative camber, the top of the tyre leans towards the centre of the vehicle, therefore the camber thrust force is towards the centre of the vehicle.  This produces a steer effect but if the left and right camber angles are the same, the steer effects on each side are cancelled out.  Even though the steer effect is balanced, the tyres are still trying to fight each other unless the steer effect is compensated for with static toe.  A common rule of thumb suggests that the steer ratio due to static camber compared to static toe is ~10:1.  So 1 Deg of static camber gives the same steer effect as 0.1 Deg of static toe.

On production vehicles, tyre camber angles are typically between -0.5 Deg and -1.5 Deg.  Running higher negative camber angles will improve the cornering power of the tyres but may result in premature inside edge wear.  On a vehicle used for track driving, this inside edge wear due to higher static camber may be balanced by the higher outside edge wear during hard cornering when the tyre looses camber to road due to body roll and camber compliance.  Static camber differences between the front and rear suspensions can also be used to make small changes to the handling balance of a vehicle.


Related posts: Bump/Roll Camber, Camber compliance


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