Specialised options can also be added to the subframe of the trailer to make driving the trailer more pleasant for the driver. The automatic tyre air pump system monitors the pressure in the tyres and adjusts if necessary. When there is a puncture in one of the tyres, this system prevents it from escalating. The continuous air supplying the tyres, helps the driver avoid travelling on the rims and provides additional time to find a safe stop before the tyre is destroyed. Another option is the self-steering axle which offers more agility. The weight of the trailer remains perfectly supported at all times.