Stripit has it right--there are 17.5" wheels available that are bolt-on for 9/16" studs. I know, because I did the change-out on my 36TK3.
Both the wheels and tires came from
www.trailertiresandwheels.com
in Edon, OH. Very knowledgeable guy. I also went with Michelin X XTA tires in Load Range J with 4805 lbs each capacity. I feel very confident with these tires/wheels under the trailer.
I am surprised that your 32 has a 17500 GVWR and not the axles/tires--are you sure it isn't 16000? My 36TK3 has a 16000lb rating, 7000lb axles.
Kinda odd if it has the lighter axles and a higher rating.
Joe