I don't doubt the unhappiness with ST failures. I do question quality statements from people with new Sialon or any other tires that haven't failed. That is not an indication that they won't fail. Come back after 20,000 miles and report. I am not necessarily a Towmax fan. I have them on my new Bighorn. However, I think investing another $1,500 to replace them isn't justified based on anecdotal evidence on a forum. Here's why I say that:
Towmax tires are on most new TT's and fifth wheels. There must be well over a million on the road. The side of the highways are not littered with RV blowouts. There needs to be more information to truly say that Towmax is worse than any other tire. Apples to apples, ya know. Also, it's important to understand the load conditions of the trailer when evaluating failures. I weighed my Bignorn last weekend. It has 11,500 lbs on the trailer tires. That comes down to 2,875 lbs per tire. I believe the Towmax is rated at 3,500 lbs/tire. That means I am loaded 82% of tire capacity. I have 7,000 lb axles. So, from a load perspective the "E" tires are fine. We drive 60mph or lower at all times and monitor pressure and temp. We have 80psi in all four tires when we leave.
Does that mean I won't have a blowout? Nope. Do GY tires fail...they do. Lots of reports on the forums. Do you see less reports? Yes. Why? One reason is that there are a lot less GY tires out there. The big question is: Will I avoid a blowout if I change out from the Towmax? No one can say I will. Will a LT tire reduce the chances of a failure? People here say it will, but no statistical evidence to support that.
One of the big problems with making decisions after reading an Internet forum is that all of the evidence is anecdotal. In the case of a product we use and can compare, like a TV or Satellite dish, anecdotes are really helpful. But with tires, it seems to me it is different. How many people are motivated to post that they are not having a tire failure with the OEM tires? There is really no motivation. As a customer, I didn't decide I wanted them. They just came on the trailer as standard. So naturally you will find many more failure reports here than happiness with the tires.
Another thing that bothers me a bit is the attack on Heartland that they buy the cheap tires (bothTowmax and Sailon are Chinese as are most tires nowadays) just to save money. Well, that may be the case, but I doubt it. There is absolutely no doubt in my mind that price is a critical factor in Heartland tire selection. Every extra dollar of cost increases the price to the customer. I'll bet that the switch to Sailon was not based on quality, but price. However, only Heartland knows why they did it. The change itself is not evidence that either brand is better.
By the way, I am not defending Towmax. Our fiver has about 3,000 miles on it (2,500 from the factory and 500 from us) and the tires are still ok. I am posting this because I wanted to point out that anecdotal evidence is not terribly helpful. Of course if you have the extra money burning a hole in your pocket, buying new tires is just as good a way to spend it as any other. I would be much happier if I could get some statistics on actual failures of the various ST and LT tires. Then I could make an informed decision.