The only ST235/75r15 tire we have available is the Westlake ST235/75R15 Radial Off-Road Trailer Tire - Load Range D # WST54FR which has a load range D and capacity of 2,910-lbs. These are a really nice, aggressive looking tire that we see used a lot on off-road style trailers like the Geo Pro, and they're going to give you a little bit beefier tire compared to your load range C tires.
With that said, there is not a load range E tire available in this size, but you could go down to the... view full answer...