Are you sure the 19480 is not your total weight? What are the DOT date codes on the sidewalls of your tires... How old are they?
Easy one first... you can run 75 psi in your front tires.
Assuming your rear axle weight is correct, then you are 1800 lbs over weight on your rear axle and doubt it's a 20K rated axle so no your tires are not rated for that much weigh and probably your rear axle too... which gets me back to 19480 is your total weight.
ASSUMING your rear axle weight is 12,600 you need to run 75 in the rear tires too. If they are more than five years old I would replace all of them. If more than 3 years old I'd put two new on the front as you do not know how well they were taken care of. Save one of the front takeoffs and carry it as a unmounted spare.
This post is my opinion (free advice). It is not intended to influence anyone's judgment nor do I advocate anyone do what I propose.
Sold 04 Dynasty to our son after 14 great years.
Upgraded with a 08 HR Navigator 45โ...