Loader Tractor Tyre Pressures

[mghley]

Just wondering your views on tyre pressures for loader tractor. We have recently taken to a MF 5712 (66 plate) with loader including soft-ride. Unfortunately no cab suspension. Tractor used for general farm duties including loading and delivering hay bales.
Finding it very uncomfortable and bouncy, Had loader off today for a bit of mowing and towing trailer and bouncing about badley.
BKT Agrimax RT 855 460/85/R38 (18.4R38) on rear
BKT Agrimax RT 855 380/85/R28 (14.9R28) on front
How low can we run tyre pressures to help problem ???
Many Thanks

 

[Skimmer]

We run 12 in the back 40 in the front

 

[haybob]

Put some front weights on and let some air out if you aren't running loader for a few days