If he has not enough to do 
Get you a Valve which you fit in Airhose of Airsupspension. 
get you a computer which gives you the weight which have to be on the Axle by which pressure Can you already buy since Years 
but,make now a recordingmachine like a Tachograph or the Recorder of Themperature by Reefers,which writes the weight you have on Wheel behind the valve
On Tractor will you have two Valves to regulate the Airsupspension
One for each side.
On normal Trailers just one on middleaxle
By Tanktrailer and Multifloortrailer will you also have two Valves,each for one side fixed on last axle
first at all is it helpfull to check weight-Balance during loading,as you also have it recorded in Case of accident.
Laterthan,when you have that Computer can we do other things too with it 