I HAVE A 10' OPEN TRAILER WITH THE 18.5-8 TIRES WHAT TIRE PSI. SHOULD I HAVE IN THEM. USED 50 PSI IN THEM LAST YEAR. MY TIRES SEEM TO BE CUPPING ON THE INSIDE EDGE. THANKS.

i read 70 pounds on my chart

Cupping is a characteristic of 18.5 and 20.5 tires run on a torsion type (no leaf springs) axle. Have never seen a solid reason why that happens. I can tell you for sure it's not the axle. Been there. Replaced one and problem was visible again within 3-4 thousand miles. Badly out of balance tires may help aggravate the problem a little.

50 psi should have likely been plenty - unless you are heavily loaded/carrying a lot more than 2 sleds in/on the trailer. Max PSI listed on the sidewall of trailer tires is not necessarily what you want/need to run in them. That max pressure is required only when carrying max. load. Depending on the weight of the trailer, you may be able to get away with 30-40 psi, allowing for a much smoother ride.

Is your trailer torsion style or solid axle. If it is a solid axle look at the axle with trailer empty it should have a slight crown(bent slightly upwards) when loaded it will straighten out.If axle installed other way tires will be riding on inside edge.

I run my tires at about 40 PSI with a torsion axle and it seems to help with the cupping.

Let me see if I can explain my theory about the cupping...If you over inflate the tires, the center of the tread will be at a larger diameter than the edges. This means that the speed of the edge of the tire in surface feet per minute (SFM) is a bit slower. Since the edge of the tread is a bit slower than the center of the tread, what happens when the edge of the tread hits a small bump that the center of the tread misses? I skids over it causing excessive wear. Think of all the little bumps that you hit with the edge of the tire that you miss with the center of the tread. This goes hand in hand with the fact that torsion axles tend to let the bottom of the tires flex out due to the design of the axle.

I have no idea if my theory is right or not. Just an idea. :crazy:

Is your trailer torsion style or solid axle. If it is a solid axle look at the axle with trailer empty it should have a slight crown(bent slightly upwards) when loaded it will straighten out.If axle installed other way tires will be riding on inside edge.
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trailer is the torsion style im going to try to run less psi. in them this year around 40 . should the tires & wheels be balanced.trailer is a 00 R&R

trailer is the torsion style im going to try to run less psi. in them this year around 40 . should the tires & wheels be balanced.trailer is a 00 R&R
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Same trailer and year that I have. Do you have the enclosure on it as well? You may want to run just a little less if it's an open trailer.