Trailer Tire Pressure

[reedtg3]

I'm planning to trailer Cattail 300 miles or so next weekend to Bahia Honda State Park and thought it might be prudent to confirm that my trailer tires are properly inflated.  I have the original (2011) Load Star 205/65-10's on the standard issue single axle Magic Tilt trailer.  I'm not sure how to interpret the information molded into the sidewall of the tires, but it looks like the recommended pressure is 90 psi cold.  If that is the case, I have been traveling short distances on dangerously under-inflated tires.  Is there a consensus on this issue?
Tom
Lake Harris, FL             

[Shawn]

For a trailer tire inflate it to whatever it says the max tire pressure is on the tire itself. That is what the tire needs to be inflated to for it to be able to handle its weight load rating.

Having said that 90 PSI sounds high. I think mine were 60PSI max when cold.

Shawn

[blighhigh]

I have the same size tires for my Horizon Cat.  When I went to purchase new tires I found out that there are different pressures for the different grades.  My grade is E which allows an inflation pressure of 90 p.s.i.  The lower grades have lower maximum inflation pressures.  By the way after reading a lot of information on trailer tires, it seems that there is recommendation to replace trailer tires every 3 to 5 years regardless of the mileage on the tire.

[hoddinr]

The tire pressure on the tire will be different depending on the Load Range of the tire.  You should have at least load range C tires, Tom.  They get inflated to 50 lbs, so you probably have load range E which are inflated to 90 LBs.  Dennis the PO of Nomad put Load Range F on my trailer and they were rated to be inflated to 120 lbs.  Unfortunately they had developed checks in between the treads and had to be replaced.  I couldn't find Load Range F tires, and my trailer guy, Jeff of Discount Trailers, said E rated tires were more than adequate.  They are rated for 90 lbs like yours.

The high pressure is to keep the sidewalls from flexing as you drive and they heat up.  Flexing tires caused by low inflation is a common cause of blow outs.

Shawn is right.  Inflate it to what it says on the sidewall, if it's too high a pressure the worse that will happen is the center of the tire will wear out before the edges.  But you'll have nice round tires going down the road.  Rarely do trailer tires actually wear out their tread anyway, developing checks in the sidewalls or between the treads.  

Also always replace trailer tires before they are six years old.  Five is recommended.  Cheap insurance against blowouts and breakdowns on the side of the highway.

Ron

[reedtg3]

Thanks, guys.  That is exactly the information I needed.
Tom

[Bob23]

This has been helpful to me. I have very low mileage but 9 year old tires on the trailer for my 1985 23/2. And I'm planning to attempt to trailer her from NJ to CLR this summer. Sounds like I need to make a trip to Eastern Marine to buy a new set rather than end up in the middle of nowhere with blown out tires. Thanks, Mates!
Bob23

[wes]

Tire pressure is just a matter of physics. The weight carried by each tire divided by the size of the tire area in contact with the road equals the tire pressure. When my 19 is on my two wheeled trailer, there's around 1500 lbs of weight on each wheel. With a contact area of 4"x4" (16 sq. in.) I would need 93.75 psi in the tire.

If underinflated, the soft tire will simply spread out onto a larger contact area so that the formula is maintained. If I only put 80 psi into my tires, the contact patch will expand to 18.75 square inches. That will create more rolling resistance and more heat, and at some point it will also deform the sidewall.

Trailers carry a lot of load on a small number of small diameter tires, so pressures are high compared to passenger cars. My tires are rated at 90, which is not unusual.

Wes

[CaptRon28]

You can probably get more than 5 years if you keep them out of the sun and don't let them sit in water or wet grass/gravel/dirt for any length of time. They will dry-rot if you don't. I've got 5 trailers (3 boat, 2 car haulers) totaling 18 tires. They are all covered and all sit on concrete squares, above the grass, gravel, etc. And yes, keep them at close to the tire pressure listed on the sidewall. Those numbers are based on load rating.

Nine years will be pushing it, especially if you haven't done the above.

[nies]

CaptRon is right on and after five years ,even under good storage, is asking for trouble, a tire blowing out on the road is never pretty............nies

[brackish]

Bob, my tires are ten years old, have approximately 3000 miles on them have been coated with 3M protectant every year for the last five, and the trailer has been parked in the shade with the boat off most of the time.  With all that said, While the tread looks very good, I plan to replace them this spring before I make any additional tows with the boat on.