ST (trailer) tires are made both radial and bias. I think that most heavier rated ST's (like E rated) are bias but I'm not sure. A principal difference between LT and ST tires is the rubber compounds in ST's are supposed to resist the deteriorating effects of UV and ozone so they hold up better in storage. Again just what I,ve heard. I tried bias tires on my 11K+ 5th wheel and found they wore badly compared to the radials I've run before. It may have just been poor tires but I've gone back to radials.
Grizzly: I got my IR thermometer from Harbor Freight. It works fine for my purposes.
Dan