Update:
Dealer delivered the new cabbed Kubota L5460 Friday without water loading the tires. So now I have two identical tractors, a new cabbed and a 2018 open station. The open station will be sold soon-ish. Both have the stock suspension seat and R4’s with 15# of air. The air ride seat is back ordered and dealer will come get the new cabbed one to install the seat when it arrives. He has offered to fill the tires with plain water at that time at no charge. No freezing concerns here.
Not sure which way I will go then, air or add the water. I’m thinking with the stiffness of R4’s even at lowered air pressure the air seat will be my best bet for a better ride for my aching back. Hope so. Should I get a FEL down the road dealer will ad water at that time.
Thanks all.