GVW for a 1500 GMC/Chev is 7,300 LBS. 2018 and older were 7,600 with the max trailer package. The 265/60/20s and 265/70/18s I took off a 2500 and 3500 found a new home on a new 1500 GMC SLT 8 years and almost 200,000 miles ago.Very, very few half-ton pickups have a 2,000 pound payload capacity. So either you didn't read my post above correctly, or you are over loading your truck.
Besides load capacity, the tougher LT E-rated tires offer deeper treads, more plies and better puncture resistance.
Now look at your p-rated/SL load rated tire, what do you need a T,H or V speed rating for? Mall crawling or proving your manhood?