Forum Discussion

Anmacc2's avatar
Anmacc2
Explorer
Jun 16, 2015

Tire pressure

I posted several questions in a different thread and received great information but this specific question got lost in the conversation...

I have P255/75R15 tires on my TV. My TT is fully loaded and weighing in at 5200lbs. My load in the TV (Chevy express van) is light, 2 people, 2 bicycles, about 100lbs misc. What tire pressure should I have in the back tires of my TV? The front tires of my TV?
  • Anmacc2's avatar
    Anmacc2
    Explorer
    Jun 17, 2015
    So, having read this I took my rig to the dealership. They confirmed this to be accurate. With the weight of my trailer, the WDH, the hitch weight, and the capacity of my TV, there is no reason to increase the beyond the normal 35psi. Thank you everyone!!!
  • Anmacc2's avatar
    Anmacc2
    Explorer
    Jun 17, 2015
    jadatis wrote:
    A P tire always is allowed to carry the maximum load up to speed of 99m/h AT 35 psi . And because when towing your maximum speed will be pretty much lower then that, you need 35 psi at max .
    That is if your rear axle is not overloaded, and thats sertainly possible, thoug its not allowed to law.
    But the type of TT makes me suspect your tires to have a large reserve.
    This would allow lower pressure even.

    JIMNLIN already assumed you use a Weight distribution hich , but do you .
    WDH transport part force on rear TV weight to front wheels and wheels of trailer, but not all.
    This means that still front axle of TV is lifted up a little, so front TV tires dont need higher pressure then for normal driving.

    There is a range in the pressure for a load or the other way around a range in the load for the presure , in wich the tire does not damage by driving, and comfort and gripp is still acceptable.

    Lowest weight at wich no bumping , I determined at if real load on tire is 85% of weight the pressure is calculated for for 99m/h.
    Highest weight at wich no damage depends on speed you drive, for lower speed more load to carry with no damage and higher speed less.

    This can be used to give the rear tires of TV a pressure that is enaugh for when no WDH used and no bumping when WDH is used.
    Same for TT tires but the other way around.

    I will not begin about my calculators because the newer Pressure/loadcapacity lists for P-tires in America now uses the same formula as the European wich is adequate for P-tires.
    So if load on axles or tires is determined propperly those lists give pressure that dont give damage.
    Capriracer most likely uses those newer lists from after 2006.
  • beemerphile1's avatar
    beemerphile1
    Explorer
    Jun 16, 2015
    I would run at or near the max pressure. You have P-metric tires and the P means passenger. They do not have a high load rating and have more flexible sidewalls for comfort, not hauling.
  • jadatis's avatar
    jadatis
    Explorer
    Jun 16, 2015
    A P tire always is allowed to carry the maximum load up to speed of 99m/h AT 35 psi . And because when towing your maximum speed will be pretty much lower then that, you need 35 psi at max .
    That is if your rear axle is not overloaded, and thats sertainly possible, thoug its not allowed to law.
    But the type of TT makes me suspect your tires to have a large reserve.
    This would allow lower pressure even.

    JIMNLIN already assumed you use a Weight distribution hich , but do you .
    WDH transport part force on rear TV weight to front wheels and wheels of trailer, but not all.
    This means that still front axle of TV is lifted up a little, so front TV tires dont need higher pressure then for normal driving.

    There is a range in the pressure for a load or the other way around a range in the load for the presure , in wich the tire does not damage by driving, and comfort and gripp is still acceptable.

    Lowest weight at wich no bumping , I determined at if real load on tire is 85% of weight the pressure is calculated for for 99m/h.
    Highest weight at wich no damage depends on speed you drive, for lower speed more load to carry with no damage and higher speed less.

    This can be used to give the rear tires of TV a pressure that is enaugh for when no WDH used and no bumping when WDH is used.
    Same for TT tires but the other way around.

    I will not begin about my calculators because the newer Pressure/loadcapacity lists for P-tires in America now uses the same formula as the European wich is adequate for P-tires.
    So if load on axles or tires is determined propperly those lists give pressure that dont give damage.
    Capriracer most likely uses those newer lists from after 2006.
  • Anmacc2's avatar
    Anmacc2
    Explorer
    Jun 16, 2015
    You're one of several people who have questioned the 15inch tires.... But yes, I'm sure. The PSI limit is 50. Is it your suggestion that all 4 tires s/b at 50? Learning is easy.... Breaking old habits and unlearning what I thought was right is harder for me. Sorry that I keep seeking clarification and thank you all for your help.
  • JIMNLIN's avatar
    JIMNLIN
    Explorer III
    Jun 16, 2015
    I have P255/75R15 tires on my TV. My TT is fully loaded and weighing in at 5200lbs. My load in the TV (Chevy express van) is light, 2 people, 2 bicycles, about 100lbs misc. What tire pressure should I have in the back tires of my TV? The front tires of my TV?

    Are you sure the chevy van has 15" tires ??
    At any rate I would run the front and rear P tires at max psi on the van and especially while towing the trailer. 35 or even 44 psi isn't much pressure.

    Now what you really need to do is find out how much weight your WD hitch is adding or subtracting to the vans front and rear axles when road ready. Not knowing any axle weight numbers can leave us guessing
  • CapriRacer's avatar
    CapriRacer
    Explorer II
    Jun 16, 2015
    Look for the vehicle tire placard. It will list the original tire size and the specified pressure for that size. On GM trucks, the vehicle tire placard will be on the driver's doorframe.

    If the vehicle tire placard lists the size you currently have on the vehicle, then that information is good enough.

    If the tire size is different, then it needs to be recalculated. The calculation isn't difficult, but it requires that the use of tire load tables, which are sometimes hard to find on the internet. I happen to have a copy and am willing to do the calculation for you. HOWEVER, I need both bits from the vehicle tire placard (size and pressure) and the new tire size.

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