Tires: wrong tires for 3/4 ton, dodge 2500 diesel, carrying capacity

Question
I had two tires installed on a 3/4 ton Dodge 2500 diesel
Big O tires installed a P rated tire 245/75-16 I have about
16,500 miles on them, and are less than 1/8" tread left. The max tire pressure as per sidewall is 30 lb. , yet the vehicle calls for 58 lbs.  Am I correct that this was not the tire for this vehicle,  and that this lead to premature tire wear-out?
Thanks for your response

Answer
Pat,

Those are the wrong tires and they are dangerous.  They do not have enough load carrying capacity.

Go back to where you bought them and have them replaced.  They ought to do that free of charge an if they balk at that, tell them you will sue if they don't.