You can't use the psi on the original tire placard because you have changed tire size, so use the actual or estimated loaded weights and the Toyo inflation table to determine the correct psi. Err on the high side - you never want to be low!
If you can't get to a scale, estimate the weight on the tire by taking 1/2 the axle GAWR and adding a fudge factor because chances are the weight isn't split 50/50. I usually add 5-10%, e.g. if the axle GAWR is 10,000 lbs, half is 5000 and +10% brings it to 5500 per tire. On the rear, its 4 tires so dived by 4 instead of two.
Former owner of 2004 American Tradition and several other RVs
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC