Mixed Tire PSI question

Discussion in 'Trailering' started by FlyGuy, Nov 2, 2019.

  1. FlyGuy

    FlyGuy New Member

    Jul 26, 2010
    2016 21SPX
    Merc 4.5L
    4 wheel trailer, standard equipment with 21SPX. One of the rear tires picked up a screw and had to be replaced, and new tire has printed on it 'Inflate to 65 PSI'. However, the other three say 50 PSI Max, and the trailer sticker lists load capacity at 50 PSI (though it doesn't say 50 PSI MAX). So, do I inflate the oddball to 65 PSI, or keep it at 50 PSI like the rest? (It's 50 miles to the launch, maybe 5x/year, probably less than 1K on the other three).

  2. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Give odd ball what the others are getting
  3. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    Looks like you bought a tire with higher load capacity rating. Like a D-rating, where the originals are C-rated, maybe? Or, if you went with the recommendation from the person at the tire store, then tell them they sold you the wrong tire and to exchange it.

    Never came across this problem before. Scof... do you think running at the lower pressure would cause it to overheat? Maybe not since that tire isn't being used to it's max? Just not sure how much being 15psi low is going to "bubble" that tire.
  4. hottoddie

    hottoddie Well-Known Member

    Jan 11, 2012
    Boston/Cape Cod
    1986 Sea Ray 390 EC
    Garmin 4212 Chartplotter
    Garmin 24 HD Radar
    Garmin 546s Plotter
    454 Crusaders
    Do you have a spare for the trailer? If not buy a tire and rim that matches the other 3 and make the "oddball" a spare. Towing those distances I would a spare.
  5. Woody

    Woody Well-Known Member PLATINUM Sponsor

    Nov 20, 2007
    N. Wisconsin/Lk Superior
    2005 420DA
    Cummins 6CTA8.3
    If it's a ST tire it should be inflated to MAX.
  6. Henry Boyd

    Henry Boyd Well-Known Member GOLD Sponsor

    Apr 24, 2007
    Newburyport, on the peaceful and serene Merrimack
    ‘09 Sabre 38 Hardtop Express “Serenity”
    Volvo D6 w/IPS450 Pods
    That’s correct, but running mixed tires would concern me. I think Dennis is right and the best solution is to have four matching tires.

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