Tire pressure on toyo open country c/t

Just put a set of open country c/t tires on my truck.
its a heavy duty tire that is rated to 80 psi.
wondering what a good tire pressure to run would be considering the truck is recommending 29 psi.
at around 35 psi the tires seem somewhat deflated and mushy.

 

Do the chalk test. https://www.tundras.com/threads/tire-pressure-chalk-test-how-to-guide.2114/

 

Call the manufacturer.

P tires are not the same as LT tires and require additional PSI to maintain load requirements. The recommended PSI for an LT tire is generally 45-50psi.

Often people will deflate them because they dont like the road feel but it all comes down to load requirements not feel.

 

What size?