Is It Okay to Run Trailer Tires at Reduced Pressure

Question:

I have purchased 2 new tires/rims 5.70-8 Load C and recommend max air is 75lbs. My question is it seems like a lot of pressure for boat w/trailer 16 ft aluminum w/18 hp motor. that maybe weights fully loaded 800lbs. Would 50 psi be safe and I usually drive 55-65 mph. Can’t find a lot of info and would appreciate input. The boat is 50 years old so I don’t want to beat it up????. Thanks

asked by: Ted H

Helpful Expert Reply:

Unless your tire manufacturer has tested the tire's load capacity at 50 psi and could provide the specific load rating at that pressure, trailer tires should be maintained at the pressure rating listed on the tire sidewall. It would seem logical that by reducing the tire pressure by 33% to 50psi would also reduce the tire's load rating by 1/3, but it doesn't necessarily work that way. At the reduced pressure, the tire's capacity would be unknown and therefore unsafe. It's best to fully inflate the tires to the pressure listed on the tire sidewall.

I've linked you to a series of trailer tire/wheel articles that you might find helpful.

expert reply by: Mike L