Tom Miller wrote:

You could buy a couple of air cylinders and use a 12 volt air compressor (
tyre inflator) to supply the air.

Even better if he connects the rear tyres to the cylinders. If he opens
the valve, the cover goes up and the back (deflated tyres) goes down
which eases loading. By closing the cover, the rear tyres are inflated
again.

Nick
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de