Wheel PSI Ratings

Discussion in 'General RVing' started by Steve H, Nov 6, 2007.

  1. Steve H

    Steve H Senior Member

    Are wheel PSI ratings contingent on the integrety of the wheel or the stregth of the valve stem?

    My resaon for asking...While still searching for a 15 inch wheel rated at 2830 @ 80 PSI capable of supporting an "E" rated tire, I came across Hi Spec manufacturing. They rate their 15 inch at 2830lbs @ 60 PSI but also add the comment that pressure rating depends on what the valve stem is capable of holding.
     
  2. Kirk

    Kirk Senior Member

    Re: Wheel PSI Ratings

    Your air pressure that a rim will contain is based upon both. The lower one applies. If you have a rim that is rated for 200# but you install one of the rubber valve stems, it will probably blow it out if you try and go that high. No rim manufacturer can design a rim to hold what the valve stem you put into it is not designed to hold.
     
  3. Steve H

    Steve H Senior Member

    Re: Wheel PSI Ratings



    Thanks for taking the time to answer!

    Here is my concern...I just bought a set of Sendel wheels that are rated for 2830 lbs. Found out after the fact that they are also rated for 65 PSI (contrary to what the salesperson told me)I can not get a hold of anyone at Sendel to find out if the wheel is capable of holding 80 PSI with metal stems!

    I don't know why anyone would manufacture a wheel for an "E" rated tire (2830 lbs) if it could not sustain the 80 PSI. Guess I am looking for a way not to return the wheels to save the $70 shipping but I do want a safe wheel/tire combination!
     
  4. DL Rupper

    DL Rupper Senior Member

    Re: Wheel PSI Ratings

    How heavy is your trailer? The "E" rated tire dosen't have to have the 80 PSI to be inflated. On my truck I only inflate the front E rated tires to 55 PSI and the rear to 75 PSI. It is based on the weight of the load they are carrying. If they don't need to carry the entire 2830 lbs, you may be able to inflate the E rated tires to your rims maximum capability (65 PSI), and be within tire weight/load capabilities. The E rated tire is usually a premium more plies type tire, but they do not require 80 PSI to be inflated properly. In fact, if they are not carrying maximum weight (2830 lbs) they will be over inflated and supporting to much of the load on the center beads of the tire. They will wear out faster in the middle. You want the tire to support the load evenly across all of the beads.
     
  5. Steve H

    Steve H Senior Member

    Re: Wheel PSI Ratings



    I agree with what you are saying but every bit of information I read from other forums, tire distributors and manufacturers, recommend running ST Tires at maximun pressure. I also read that underinflated tires overheat and are prone to failure. To tell you the truth...I don't understand why trailers have such an issue...I never (knock on wood) had a blow out in anything (40 years of driving/riding) exceptwith my5th wheel. Treated it good too...check pressure daily, nevered curbed, always under 65 mph etc. Tires were brand new (600 miles)

    Apparently it is OK to vary pressure on LT tires but I am told this is not appropriate for ST tires. I justmounted a set of Denman Express ST's.

    My Springdale has a GVWR of 10,020. Haven't put it onour local CAT yet but there is not much in it! (I am guessing 9000) Empty weight is stickered at 6380.When I had my first blow out it was basically empty...no fluids, no propane etc.

    Anyway...thanks for your help!
     
  6. DL Rupper

    DL Rupper Senior Member

    Re: Wheel PSI Ratings

    Yeh, my "E" rated tires are LT tires. I didn't know the ST tires even came in "E" load rating. I only had 1 blowout in 35 years of driving cars/trucks until I had 2 blowouts in one year with my 5er. I switched to Michelins XPS RIB commercial light truck tires and haven't had any problems since. I guess with 16 inch tires you get more options.
     
  7. Guest

    Guest Guest

    Re: Wheel PSI Ratings

    Hey DL that's what i run on the class a ,, the mich,, ribs ,, been great so far ,, and i would by them again (damn i wish i had not sold my shop now) i stocked a few tires ,, but did get a discount from the tire venders,,, OH WELL :disapprove: :)
     
  8. Poppa

    Poppa Member

    Re: Wheel PSI Ratings

    You know I have to syick my 2 bits in.

    The reason for the flat can be attributed to others things. One your trailer should be run as level as possible. I know there are the so call equalizers on springs but I ran a trailer loaded heavy to the front axle and blew out 2 tires before I could shift the load.

    The other thing that can attribute to an early blow out is the pair of axles not being paralell (bnever could spell that word) and the tires runing cocked some what, getting hot and poof. Know what I mean. and the last thing is the breaks dragging just a little bit, going unnoticed will also cause the tires to get got.
     
  9. benwd

    benwd New Member

    Re: Wheel PSI Ratings

    kirkquote---" If you have a rim that is rated for 200# but you install one of the rubber valve stems, it will probably blow it out if you try and go that high."

    Common sense says otherwise. If the valve stem hole in the rim is 1/2 inch in diameter the force pushing against the stem is 20% of the tire pressure. At 200 psi the force on the stem is only 40 pounds. Try pulling one out, it takes a lot more than that.
     
  10. TexasClodhopper

    TexasClodhopper Senior Member

    Re: Wheel PSI Ratings

    benwdquote --- "If the valve stem hole in the rim is 1/2 inch in diameter the force pushing against the stem is 20% of the tire pressure. "

    I'm curious how you arrived at this conclusion. Would you elaborate, please?
     
  11. benwd

    benwd New Member

    Re: Wheel PSI Ratings

    texas----A half inch hole is 20% of a square inch. pi r squared, 3.14 X 0.25 X 0.25 = 0.196. Air at 200 psi X 0.196 = 39.25 lb.
     
  12. TexasClodhopper

    TexasClodhopper Senior Member

    Re: Wheel PSI Ratings



    Well, wouldn't the durometer of the rubber of the valve stem enter into the equation? Does the rubber of the valve stem tend to hold back the pressure, too? It sure seems kinda tight in there. Isn't there any effect from the friction? Maybe the manufacturer of the valve stems has some specs on them. Now that would certainly explain it.

    Isn't the hole in the back side of the stem smaller than the hole that it mounts into? Why wouldn't you calculate with that smaller diameter?

    Just seems like it is more complicated than just a hole in the rim. Is there more to the engineering than that?
     
  13. benwd

    benwd New Member

    Re: Wheel PSI Ratings

    Sure, there's more to it. But, the force pushing out from tire pressure is according to the diameter of the hole in the rim. There are other forces, like friction that increase the total force to push out the stem.
     
  14. C Nash

    C Nash Senior Member

    Re: Wheel PSI Ratings

    Now Tex and benwd, you'll done gone and got way above my learning with all this high tech knowledge :eek: Just put sawdust in the tires and don't worry about it ;) Lifes to short to worry over the small stuff :laugh:
     
  15. DL Rupper

    DL Rupper Senior Member

    Re: Wheel PSI Ratings

    Metal valve stems work on my 5er. Had a lot more problems with rubber stems. The rubber stems leak air and metal stems don't. :approve: They put metal stems on my wheels when I switched to the Michelin XPS RIB light commercial truck tires. End of problems for the last 8 years.
     
  16. C Nash

    C Nash Senior Member

    Re: Wheel PSI Ratings

    Hmm, Are we putting this in tires now :laugh:
     
  17. Guest

    Guest Guest

    Re: Wheel PSI Ratings

    Agreed ,,C what happens if this stuff goes into tires HMMMMMMMMMMMMM :laugh:
     
  18. C Nash

    C Nash Senior Member

    Re: Wheel PSI Ratings

    Guess it cleans them out and makes the air smell good :laugh: :laugh: Well, you know, that air sure does stink when letting out :eek: Guess we'll be drinking that stuff next :laugh: :laugh:
     
  19. TexasClodhopper

    TexasClodhopper Senior Member

    Re: Wheel PSI Ratings

    We all know by now that this "calgon" topic just goes round-n-round-n-round-n- ........... now here's proof!
     
  20. Guest

    Guest Guest

    Re: Wheel PSI Ratings

    That's :laugh: :laugh: :laugh: Tex
     

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