LT is softer in the sidewall than ST. LT is designed for traction and softer ride. ST is designed for a following unit, not a driven unit. Following is a different set of design considerations than driven design considerations.
I have run both types and without issues. I would rather run ST's and will as long as Maxxis keeps making them in load range E for 15 inch wheels.
No man has a good enough memory to be a successful liar. Abraham Lincoln
2016 36FBTS Pinnacle
2016 F350, 6.7, 4x4, DRW, long bed
B & W Companion 5th wheel Hitch