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Paulx's avatar
Paulx
Explorer
Apr 15, 2014

Trailer tire questions

Hi, I have a Salem 181BHXL trailer which has two axles and about 3700 lb dry weight. The tires are H188ST, size is ST205/75D14 which has a max load of 1760 lb @ 50psi. The trailer was delivered from the dealer with 40psi in the tires.

I have not found a table for load/inflation for this tire but the goodyear table has the same sized tire at the same pressure taking the same weight, 1760 lb. At 40 psi it takes 1530 lb.

Just wondering what I should use for my pressure. We don't intend to load this trailer to the gills due to fairly low tow vehicle capacity. Is 40 a good pressure? I know the tires can be unevenly loaded but even with 1000 lb of payload, that's 4700 lb, divided by 4 tires is under 1200 lb per tire which is 25 psi in the load table! Do people really go that low with their tires in light trailers?
  • Atlee's avatar
    Atlee
    Explorer II
    Apr 16, 2014
    I'll add my support for the max pressure for the ST tires. I can't say I'm experienced, but I have listen to the majority advice on this board, coupled with what I think is reasonable.

    I did just return from a 7,942 mile trip to the west coast, which included climbing up to 7-8k feet and going down to 282 feet below sea level, and my tires did just fine.

    I've had two other travel trailers for about 1 year each, keep the tires aired to the max pressure, and never had a problem with tires.
  • BarneyS's avatar
    BarneyS
    Explorer III
    Apr 16, 2014
    My advice is to listen to the experienced RVers on this board. They say to air up the tires to the max as stated on the tire sidewall. In my opinion, that is good advice and is what I have been doing for many years. I have never had a tire problem in all that time (knocking on wood! :).
    By the way, you might be very surprised at how much weight you will put in your trailer - most people are! :E
    Barney
  • Paulx's avatar
    Paulx
    Explorer
    Apr 16, 2014
    Well it's funny, the reason I am asking is because of the official label and because of what the manual says. The label says 50 psi and shows the max payload, which is 3600 lb (almost the same as the trailer dry weight, 3700 lb). The manual goes into great detail about tires and weights, saying the numbers on the labels were chosen to take care of a max load. But nowhere does it say, "use 50 psi no matter what load you have in it". It kinda sorta implies 50 psi is to handle the max load. No way am I ever going to put 3600 pounds of stuff into this trailer.
  • JLTN_James's avatar
    JLTN_James
    Explorer
    Apr 15, 2014
    Paul,

    Even if the trailer isn't loaded to the max, I recommend max sidewall pressure in the tires.

    Since you're in The Equality State, it's almost all downhill from there. Tire pressure gauges measure the pressure inside the tire against the atmospheric air pressure outside the tire. As you drop in elevation, the atmospheric pressure increases, so the measured pressure inside the tire decreases. This can be between 2-4 PSI. See this article: Tire Pressure vs. Altitude

    I kept my trailer tires at the max, haven't had a blow-out, and tire wear has been pretty good. Only one RH tire has been damaged and that was probably from hitting the occasional curb in tight RH turns.
  • Campfire_Time's avatar
    Campfire_Time
    Explorer
    Apr 15, 2014
    Don't compare ride quality of an ST tire to a vehicle tire. They are entirely different animals. Try not to read too much into a "harsh" ride for the trailer. ST tires are made for trailers, they have stiffer sidewalls and a built to support the weight. The trailer is built to sustain the bouncing and stress on the road within normal use. The construction is somewhat fragile yes, but only if do things to it that it wasn't built to do, like try and take on a rough off road trail.

    Check your manual for proper inflation. I've yet to see one that didn't recommend anything other than what it says as a max on the tire. Mine says 50 psi as does my trailer's manual.
  • Paulx's avatar
    Paulx
    Explorer
    Apr 15, 2014
    Wow, unanimous.

    By the way I can see *some* use for a softer ride even if nobody is riding in it. The body of the coach should not be stressed too much I think; after all the construction is somewhat questionable or fragile. Also it may be less likely to get tire damage when hitting potholes.

    Keep in mind trucks with heavy springs, running unloaded, are usually very harsh. Put a load in them and they become reasonable.

    I just remembered the FAQ had lots of threads about tire pressure. Thanks for the advice though.
  • Bull_Rider's avatar
    Bull_Rider
    Explorer
    Apr 15, 2014
    Pump em up to the max pressure listed on the side of the tire. Measure the pressure when the tire is cool, like first thing in the morning. The tire pressure will increase by about ten pounds when you get em warmed up and at travel speed. I don't go over 65 MPH when towing.

    Don't air down tires that are warm from driving.
  • fla-gypsy's avatar
    fla-gypsy
    Explorer
    Apr 15, 2014
    There is no issue with taking it to the max sidewall pressure. It would be preferred IMO.
  • downtheroad's avatar
    downtheroad
    Explorer
    Apr 15, 2014
    I have been round and round with this same question..
    For the trailer, I keep it simple...max pressure as shown on the sidewall.

    It has been a good decision...no problems.

    Some will say weigh the loaded trailer and air them down for a softer ride or less tire wear...I don't care about "softer ride." I'm not riding in it.

    Wear? I replace my tires every 5-6 years anyway.

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