Best choice tires for large Keystone

[mtlakejim]

We just purchased a 2018 High Country HM 381TH. This is a 41', three axle, toy hauler hybrid. I have heard a LOT about "Chinese tires" that come stock from the factory. Having experienced what a blowout can do in the past I am naturally concerned.

While we are not made out of gold, I do spend money where it matters and obviously tires matter, a LOT. Our typical load will include a motorcycle and kayaks in the garage. I generally tend to drive with the flow of traffic pacing with the 18 wheelers on interstates (with a good front cushion). That means that it is not unusual for me to run at about 74mph on open stretches of highway. I generally think it is far safer to go with the flow than drive the speed limit (its the idiots that drive really fast and lane change or the slow pokes blocking traffic that get us all in trouble isn't it?). For certain, I ALWAYS like to have a cushion of safety in the tire rating. That being said I have the following questions:
1. Are the factory tires safe for the for the first year (we typically just camp a couple times a month within a 3 hour drive from the house with an occasional longer trip maybe once per year)? Or should I replace them immediately?
2. What is the best mid priced (as in we don't want the cheapest but don't want to break the bank either) tire brand and what load range/rating should I get to have a good safety "cushion"?
3. Related to above, I hear a lot about ST, LT and such ratings. What is really the best to run on a trailer? Is it a cost thing or what?