CVR222NV
TDR MEMBER
You are correct in that you definitely do NOT want to run 19.5 tires under pressurized for the simple reason that there is no bead lock that hold the tires onto the rims and ALSO excessive sidewall flex from low pressure can and will eventually lead to sidewall failure from fatigue.
The industry term for it is "Sidewall Zipper Failure" which obviously cannot be pretty.
I am not sure what is the lowest pressure you can run in YOUR tires (it differs mostly by size, but also by manufacturer). For instance, when unloaded and not towing I can air down the 225/70/19.5 G tires on my truck to 70 psi based on the load inflation chart, and IIRC one of the Michelin 19.5 tires (forget which one can be aired down to 65 psi) but that is the lowest I have seen for these tires. I highly recommend finding the load inflation chart from the manufacturer for your tires and air up accordingly. Meantime, I owuldn;t run any less then 75 psi UNLOADED and more if you are running loaded/towing.
All that being said, keep us updated how those tires work out for you mileage and ride wise.
Thanks Seafish! I could not find a load inflation chart on the Hercules website so I emailed them. Hopefully they respond. I did find a Goodyear load inflation chart and for the post 2006 245/70R/19.5 it shows a minimum of 80 psi. This chart has the same max psi of 110 psi and single axle rating of 4540 as the Hercules H-702 so it is probably close.