Forum Discussion

Geocritter's avatar
Geocritter
Explorer
Oct 05, 2014

Tire air pressure

I’ve been keeping the tire pressure in my 1994 Class A 33’ Holiday Rambler with 235/85R 16 tires inflated to 65 psi, typically road heat will increase the pressure to about 70-73 psi after I’ve been underway a while (I have pressure/temperature minders on each wheel). I don’t believe I’m at all heavily loaded and typically travel with my water tank and gray/black water tanks empty. I haven’t had any tire problems (knock on wood) in the 2,500 miles I’ve driven on this journey so far. Soon I’ll be making a 2,450 mile journey back to Texas, which unlike earlier this year will be in a steady probably 400 mile a day push.

I’d like to hear from other people who have similar rigs and learn what tire pressure they run with. I realize that I should be weighing the rig at each wheel, but I’m hoping there’s some rule-of-thumb here for a normal rig carrying a standard load.


The Behemoth taken earlier this year.
Class A
  • CapriRacer's avatar
    CapriRacer
    Explorer II
    Oct 06, 2014
    rdfugere wrote:
    If I get this correct, I have to weigh each tire and inflate the tire accordingly. If it is so important to get the weight that's on the tire, it would have to be weighed before each trip. I can see weighing the motorhome once to get an idea but if tire pressure is that exact it must be weighed before each trip because each trip is different and you may carry more or less weight each trip.


    You don't need to get so exact. Tires are fairly tolerant of over pressure.

    Remember, the tire load charts are MINIMUMS! You need to inflate for the worst case. I don't think any tire ought to be loaded more than 85% of its capacity at the pressure being used.
  • Mr_Mark1's avatar
    Mr_Mark1
    Explorer
    Oct 06, 2014
    rdfugere wrote:
    If I get this correct, I have to weigh each tire and inflate the tire accordingly. If it is so important to get the weight that's on the tire, it would have to be weighed before each trip. I can see weighing the motorhome once to get an idea but if tire pressure is that exact it must be weighed before each trip because each trip is different and you may carry more or less weight each trip.


    Weigh the coach as you would normally have it loaded. I would probably go with full water, empty holding tanks, full fuel (propane and diesel/gas). Then go to your tire manufacturer charts and fill the tires to the correct weighted pressure.

    If nothing else, fill the tires to the max cold pressure. On ours (2008 Monaco Dynasty), that would be 120 lbs. cold pressure. Can't go wrong with the listed cold pressure until you can get the coach weighed.

    Good luck,
    MM.
  • rdfugere's avatar
    rdfugere
    Explorer
    Oct 06, 2014
    If I get this correct, I have to weigh each tire and inflate the tire accordingly. If it is so important to get the weight that's on the tire, it would have to be weighed before each trip. I can see weighing the motorhome once to get an idea but if tire pressure is that exact it must be weighed before each trip because each trip is different and you may carry more or less weight each trip.
  • larry_cad's avatar
    larry_cad
    Explorer II
    Oct 05, 2014
    Rated tire pressure on the tire sidewall, or proper tire pressure for a given load weight is ALWAYS measured with "cold" tire air. Cold meaning tire air is the same temperature as ambient or surrounding air. Elevated tire pressures at higher traveling temperatures are not considered for purposes of inflating tires. This increase is taken into consideration by the tire manufacturers and other than a curiosity, it is irrelevant.
  • tommy_g's avatar
    tommy_g
    Explorer
    Oct 05, 2014
    I run 79lbs cold in all 8 of mine. The unit only has 79k miles, 47 states and 6 provinces but we may yet have pressure problems. My TPMS does not alarm on 100f plus days and the tire pressures rarely exceed 85lbs. Why 65lbs as opposed to the max?
  • Born_To_Travel's avatar
    Born_To_Travel
    Explorer
    Oct 05, 2014
    I too have a Class A of the same vintage with 16" tires and I run 65 psi in them as well with a TPMS... They run about the same pressure on the road and my longest day was a 850 mile day in about 90 degree weather and I had no problem as well... Just keep monitoring them and you should be fine...
  • wolfe10's avatar
    wolfe10
    Explorer
    Oct 05, 2014
    Sorry, our GUESSING at the correct PSI is not going to help you.

    You need to find a scales (many truck stops) and at least weight each axle.

    Better, weigh the individual wheel positions and use the heavier wheel position to go to your tire manufacturers inflation table to find the correct MINIMUM PSI for all tires on that axle.

    In many states, contact your local DOT office-- the ones who weight trucks. Ask if you can meet them at their office at beginning or end of shift to have your coach weighted. I PROMISE you they will be ecstatic that you are interested in safety and will be happy to do it.
  • darsben's avatar
    darsben
    Explorer II
    Oct 05, 2014
    If you are NOT going to weigh the rig then the rule of thumb would be inflate to the maximum pressure.
    You carry more weight than you think

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