Gross weight on trailer = 12500 lbs. Is that on the axles ??
12500 lbs on the axles on a tri axle trailer equates to 2000 lbs per tire minimum requirements.
Six LT E at 3042 lbs is 18250 lbs of capacity. Thats gonna' pound that light tri axle trailer unnecessarily.
The LT215/85-16 E and LT225/75-16 E at 2680 lbs will give you 16000 lb capacity.
The Goodyear Wrangler LT215/75-15 D at 2090 lbs capacity will give you 12540 lbs capacity.
I use the BFG Commercial on my 11200 lb 5th wheel RV and other equipment trailers. Zero issues.
Just sayin'