Workshop tip: How to eliminate erratic driving behaviour safely and analytically

Sometimes a vehicle does not run smoothly in the truest sense of the word - usually after the fitting of new tyres or complete wheels, but sometimes also abruptly after several hours of operation. Our workshop tip shows you how to eliminate erratic driving behaviour safely and analytically.

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Instead of fitting new tyres or wheels, the first thing to do is to investigate the cause. Because in many cases, the jumping, swaying or bouncing vehicle can be controlled by adjusting the air pressure. Much rarer is a faulty wheel assembly, but in that case the tyre has to be remounted onto the rim. New wheels, on the other hand, are only required if they do not match the machine's performance class or if the material is fatigued.

Abnormal driving behaviour

  • A pronounced radial runout of the wheel can best be recognised on the moving machine from the outside. The tyre and rim have a high and low point within their manufacturing tolerance. When both high points have been mounted on top of each other, the millimeter-sized manufacturing tolerances add up to a visible deflection. Remounting at an offset of 180° usually improves the running smoothness significantly.
  • If uneven running is building up while driving, this is often caused by too low tyre pressures.

Visual inspection

  • Wear profile: One-sided signs of wear at the shoulders or towards the centre indicate that the air pressure has been permanently set incorrectly.
  • "Flat spots": after longer periods of inactivity, tyres may show uneven running behaviour. The so-called "flat spot" will even itself out over time.
  • Characteristic curves: if the fine characteristic curves along the tyre sidewall are not uniformly concentric with the rim flange, there is a risk of serious material damage. The tyre must be remounted onto the rim again.

Changed usage

Adjusting the tyre pressure can improve smooth running,

  • if the frequency of road usage has changed
  • After heavy implements such as front loaders have been mounted or demounted
  • If dysfunctional rotational conditions between the rear and front axles leads to tension in the drive train.

Special case: adjustable rim

Adjustable rims must first be expertly centred before they are screwed on, otherwise uneven running is pre-programmed.