A C tire is equal to 4 ply and a D is equal to 6 ply, E, 8 ply.
Load range C = the old 6 ply rated tire
Load range D = the old 8 ply rated tire
load range E = the old 10 ply rated tire
All three tires are a two ply carcass however a D has heavier/thicker plies than the C tire ...E tires have heavier/thicker ply than the D tire.
Were not talking off road tires here but tires on a very lightweight TT.
The topic is does the OP need 205/75-14 D tires replacing 205/75-14 C tires on a 4500 lb trailer with 1125 lb load capacity per tire.
Librty02 reply make the most cents/sense.
Now if the OPs trailer was at max tire load on those OEM C tires then of course D tire upgrade makes cents/sense.
Hope the OP can separate those that reply about tires on a trailer vs tire on trucks...quads.....cars/etc.
OP what are your thoughts now ??
You went 7 years on those china made bombs. Why not a new set same brand for another 7 years.