I have 2 gauges and 2 release valves and a switch for 12v compressor under drivers seat, previous owner/installer have a label stating 7 bar max, plated 4250kg, run about 3.5 bar but have taken it up to max when negotiating a steep change in incline to stop tow bar supports grounding as its such a large overhang, also comes in handy when levelling up as its nearly 2 inches difference in height at either end of scale.
