Tire advice needed,long trip planned

I am a 10 year Sunnybrook 37ft 5th wheel owner and know the weight range you are in on just two axles. I have three axles and still suffered the disaster that ultimately comes with the typical new RV. It is not worth the risk to life and limb to run those tires. You have a great deal invested so don't skimp on tires. I finally quit the quest for cheaper answers and installed the only real solution to your problem and that is Michelin XPS RIB tires. The $$$ is tough but you can even see the difference when you compare them to your old ones. Order them online and have a real professional alignment shop (truck) true, balance and mount them. You will never know how much agony you will avoid. By the way, it is also critical to get your heavy rig weighed wheel by wheel so you can try to distribute your weight properly, see that the rig runs level and keep the air pressure correct. Sorry for the long speech but I get tired of so many half baked opinions on these forums. Have fun and don't try to cut corners on your connection to the road!