Would that be 12,000 lbs. GVW, or actually whats on the axles. If those Westlakes are OEM, they are probably past due for changing out. From what I've read, there aren't any really bad ST tires out now, except for the super cheap no-names from China. The Hercules are supposed to be good, and the new Carlisle are supposed to be good. And the Goodyear Endurance, seem to be okay if you don't put a lot of miles on your trailer. Their tread depth is shallower than other brands so you won't get the mileage that you might with other brands. But most trailer tires age out before they wear out, so not a big deal overall.