The present paper reports for the first time experimental results of the measurement of steady state side slip effects of plastic tyres commonly used for ground floor industrial vehicles. Two different types of lyres, one steering lyre and one tyre of the load wheel have been examined on a tyre testing rig by measuring the lateral force for different side slip angles. Additionally the influence of the rolling speed and of the wheel load has been taken into account The resulting steady state side slip characteristics of the plastic lyres quantitatively looks like the characteristic of conventional pneumatic tyres. In contrast to the wheel load the rolling speed has no significant influence. Based on this result the dynamic behaviour of industrial vehicles can be examined using linear or nonlinear models for which it is useful to expend the presented analytical approximation of the measured characteristics.