Tires: wheels for 105 psi tires, hankook tires, inflation pressure

Question
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Followup To
Question -
Barry,
    Do we need special wheels for the Hankook 7.5R16LT 105 psi tires we recently purchased for our goosenect trailer?  We previously ran OEM LT235/85/R16 tires inflated to 80 psi, but these tires just weren't doing the job for us.  The Hankook tires are rated for 105 psi but the tire dealer said to run 80 psi in them because of our wheels.  However, I've come to see that rated tire pressures are extremely critical for good performance.  Please advise if we should run the Hankook tires at 105 psi and if, so, will our current wheels carry the load.

         Thanks,
         Roger
Answer -
Roger,

I just hate when a tire dealer steers someone wrong, especially when they have the information right in front of them.

An LT235/85R16 Load Range E has a load carrying capacity of 3042 pound at 80 psi.  (It should say that on the sidewall as the "single" value, not the "dual".)

I'm a little unsure of what the current tires say, so I'll need you to be very careful and read the info on the sidewall.  (This tire wasn't built to US standardizing, so it isn't listed in my standardizing book.)  But if I have this right:

1)  The size is 7.50R16LT Load Range F
2)  The max load single is about 3300 pounds at 105 psi.

Those are the key things I want you to check.

If I am close on the load, then in order to carry the same load your former tires were capable of carrying (3042 #), you need about 92 psi.  So while your current tires may have more load capacity, they do that due to the higher inflation pressure.

Now about your wheels.  They ought to be stamped somewhere with the maximum load and inflation pressure.  I'll bet these are 80 psi wheels (fairly common for LT tires and wheels) and are not rated for 105 psi - or even 92.

Get back with me on what the tires actually say.  I could be wrong on this and it's no sense in your having bad info from me when the correct info is written down where we can find it.

Barry,
    I'm sure you know this already.  The Hankook tires are Korean as are Kumho tires.  The ranchers here in South Tx use them on their cattle trailers.  The consensus seems to be that the Kumho tires are really a good tire but the Hankook tires give good service also.  I couldn't find any of the Kumho tires.  We haul mesquite wood and heard about the Korean tires after we had trouble with the OEM tires.  Tire ratings for the Hankook tires:
         single: 3330
         dual: 3175
To restate my major concern: should we put 105 psi in the Hankook tires because that is the recommended cold pressure?  Then, will the 80 psi rims fail under these pressures?  In the past, we ignorantly abused the OEM tires by sometimes running them underinflated and then by periodically overloading the trailer.  Even under these conditions, the tires were forgiving and gave good service 85% of the time.  Hopefully, with proper care, these Hankook's will give good service 100% of the time.

         Roger

Answer
Roger,

It is just as I suspected.  If you run the tires at 85 psi they will be overloaded.  However at 105 psi, the rim is now in question.

You'll have to look at the rim to get the answer.  It ought to be stamped somewhere on it (and it might be inside the rim where you have to take off the tire to see it).  It ought to say the maximum load and the maximum inflation pressure.  The dimensions might be in kilograms(kg) or bar (pressure), so you may have to convert.

But they way rims would fail if there is too much load and / or inflation pressure is that they would be cracks in the rim, especially where the rim turns under the bead of the tire.

Hope this helps.