I would argue that ST tires have a higher rating ONLY because of their speed restriction. The marketing claims of special construction and materials just does not seem to be there. They rot quickly and fail way to often. ST manufacturers also note that they loose 10 percent of their capacity for each year is service. Three years and a tire rated to 3420 is only good for 2394 pounds, 5 years and you are at 1710 pounds. Send them back to local utility trailer service, they are NOT for SEEING America with a large 5th wheel trailer.
If you have 7K axles get GY G614 or Sailun S637's. If you have 5.2 or 6K axles, get a good LT235/85R16E or LT245/75R16E. If you have 15" rims and tires upgrade to 16" LT's, even if you have to change hubs.
SNOKING
Oh I agree but lets be clear here..... ALL tires have a scheduled service life and all tires essentially time out in approximately 5 years. Dont believe me?..... Call up a few reputable tire shops and ask them. Thats not an definitive statement for all tire types either but a general rule of thumb for the tire industry. And ST tires also have higher load ratings because their construction is designed to hold up the load "laterally" whereas passenger tires are also designed to hold all forces equally in acceleration, deceleration, and turning. So the capacity in ST tires is more like a jack stand.
Not to mention that people often misunderstand the tire capacity which should be under their 5th wheel. Unlike TT's, 5th wheel axles only hold a percentage of the weight as the truck axle holds the rest. So for example, my 14,000 lb 5th wheel is a triple axle. I have six E rated 10 ply tires which have a capacity of 2830 lbs each. At their maximum psi rating (which all ST tires should be run at) have the capacity to hold up a 17,000 trailer. That said, my pin weight is roughly around 3000-3500 lb depending on the load. So therefore my axles are only seeing around 10,000 lbs at most given times. That means I have around 7,000 lbs of reserve capacity in my tires. Far more than the trailers capacity. Even if after the supposed 5 year / 10% theory, I still have the tire capacity.
Now all that said, if you see a 5th wheel with only four axles which weighs anywhere over 11,000 lbs then its likely that even if that trailer is equipped with E rated 10 ply tires, over time there will be capacity issues by running the tires at their maximum weight capacity rating. Not to mention people have a habit of letting their trailers sit for months and months on end without moving and also running tires at too low of pressure by either thinking this helps soften the ride of they just fail to check period.
Lastly, in reality that 4 axle trailer weighing in around 11,000 - 12,000 lbs should have 16" rims and be running a G rated tires but thats not always the case. So point being..... We can get all ****** off at ST tires but the blame game doesn't lie completely on the shoulders of the tire companies as the trailer manufactures and the consumer play much larger roles in tire failures than these forums give credit.