AOR recommends 33psi (cold) in their Quantum (2200kg -2400kg ATM) tyres, and the Q has independent coil suspension, with dual shocks per trailing arm. This pressure is recommended, as I understand, to lessen road vibration transmission through to the chassis and other components. I've gone as low as 21 or 23 psi on bad corrugations but never more than 35.
Whilst high tyre pressures might reduce rolling resistance by a smidgen, and thus fuel consumption. Nothing comes for free. The price one pays is a harsher ride, with the tyres less able to absorb as much of the road undulations and roughness, as if they're at a lower pressure and better able to flex.