I have six commercail grade all steel ply carcassSailun S637 ST235/80-16 load G 4080 lbs at 110 psi on my GN triaxle stock trailer with 7k axles. This trailer makes short runs out to 450-500 miles at legal 75 mpg speeds and return the same day. The S637 are L speed rated.
When fully l;oaded I can spin the trailer on the center axle around close spaced loading docks areas. Doesn't faze these 110 psi tires. Now those soft 80 psi rated poly carcass ST tires is a different story.
Sailun also offers a S637 ST235/85-16 G at 4400 lbs the tire is a bit taller than the 235/80 tire plus a thicker tread for more miles of service.
Just make sure your present wheels are 110 psi rated.
JMO... that trailer with just 7k axles doesn't need 17.5" tires and wheels.
