I just did a forum search for "Towmaster" and there are 7 threads here about the brand.
Greenball has long been a manufacturer (actually distributor) of industrial and agricultural tires. I've got Greenball products on my tractor, on the trailer that I haul it with (they are Towmaster) and also have Greenball on one of my ATV's. So far, no problems with any of them, but only the trailer tires are Towmaster.....
Be careful with Greenball and Towmaster. Although Greenball is a distributor, they are not the manufacturer. They don't sell "Greenball ST tires" They sell "Towmaster ST tires" some are made in China and perceived to be of questionable quality, some are made in Indonesia and perceived to be better in quality. Do they match Maxxis and Michelin in quality? That's a question with different comments depending on personal experience. Brand loyalty runs deep in tires just as it does in tow vehicles and RV's.
I think Outbackmel probably has the most documented comments about the tires, and from what I think I remember, he was pretty well pleased.
I've got about 1500 miles on my flatbed trailer, it weighs about 7500 lbs loaded and has the Towmaster ST225 75R 15 LRE tires. Never a problem with them, but I was a little disappointed that they only have a 2 year warranty. Since they came standard equipment on the trailer, I had no choice unless I wanted to replace them at purchase and only get $40 a tire in exchange. ??? WTH ??? Anyway, I kept them and they seem to be doing OK. I just wish they had a longer warranty since I probably won't put 3000miles on them in 5 years and that's 3 years out of Greenball's warranty period of 2 years.
2015 F250 6.7l 4x4
2014 Cougar X Lite 27RKS