Nancy, I think it is likely that you have that reversed: the 20 psi sticker value is probably a minimum
or recommended pressure for the original tires to support the trailer, not a maximum; the 35 psi value is probably the maximum
pressure for the new tires (and would be required for maximum capacity), not the minimum. I don't know, but I suspect this is the situation.
I agree with Byron on two points:
- tires (at least some of them) have changed
- tire inflation pressure is controversial
I suggest using the Google search feature in this forum to look for "tire pressure" and be ready for a lot of reading - rather than re-launching the whole debate.
I also suggest looking at the load capacity information on the tire's sidewall, and comparing it to the axle weight
of the trailer, to check that the tires have sufficient load capacity for the trailer.