It might be time for me to mix things up a bit!
1) An ST tire carries much more load than a similar sized LT tire: LT235/85R16 LR E = 3085# @ 80 psi, ST235/85R16 LR E = 3640# @ 80 psi (+18%). That means that at least one of the government tests is more stringent for ST tires.
2) US Government testing procedures do NOT produce a tire that will perform well in the US market (This applies to Passenger Car tires, LT tires, AND ST tires!) Nowadays, the tire has to EXCEED the government minimums by a good percentage to perform adequately.
