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Old 12-04-2014, 08:19 AM   #11
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If what etrailer says is correct (always inflate to max pressure) why does Goodyear put out a table to show pressure vs load on the marathon?
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Old 12-04-2014, 09:41 AM   #12
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Thanks llberg for the link back to etrailer about the max pressure on ST tires. The author there needs to supply me more info/supporting data to convince me of what he said.

Regardless, you and I are covered as we have "D" rated tires inflated to their max (and the max allowed by the wheels) of 65 psi. Once again, this load range rating of 2,540 lbs per tire surpasses the axle ratings and the actual weight of the RV at each tire.

I am not faulting fellow RVer's who tow a similar rig with "E" rated tires. I believe there was no benefit to me with my known weights and the information passed on to me by both Lions Head wheels and Maxxis technical support.

To me it was a great relief to get the factory spec tires off before a blowout and at the same time upgrade to a known good reviewed "D" rated tire (ST Maxxis 8008). Moving farther up the list to an "E" rated tire would not have improved my comfort zone that much more, if at all. Time will tell if I made the right decisions.
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Old 12-04-2014, 12:19 PM   #13
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Originally Posted by llberge View Post
Ron, I also really wanted to put load range E on my trailer for the additional strength of the tire. Here is just one of the places that talked me out of it. I read similar things on various other sites.

Thanks for your input.

Can a Load Range E Trailer Tire be Used in Place of a Load Range D Trailer Tire | etrailer.com

Etrailer just wants you to sell you some new rims. A blanket statement saying all ST must be run at max pressure is just silly. You are going to build heat if your load exceeds the pressure rating for that load regardless of whether the tire is a C D or E. Running 65 in an E on a D load is not going to hurt anything, but it will give you a stronger tire.


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Old 12-04-2014, 05:57 PM   #14
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Maxxis also puts out a load pressure chart for there ST tires.
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Old 01-09-2015, 03:05 PM   #15
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Originally Posted by Happy Vibe View Post
If what etrailer says is correct (always inflate to max pressure) why does Goodyear put out a table to show pressure vs load on the marathon?
Load inflation tables work well for normal vehicles like cars, trucks and motorhomes. These have tires "at the corners" of the vehicls so when it turns a corner all tires rotate around centers that "point" to the center of the turn radius.

They also work reasonably well for single axle trailers as the trailer rotates to also point the tires toward the center of the turn.

The problem occurs with multi axle trailers. It is physically impossible for all 4 or 6 tires to point to the center of the turn. The end result is that the tires are dragged around the turn and this puts VERY high internal stress loads on the structure and this can cause internal cracking which can lead to belt separations.
Running the sidewall inflation pressure will lower these stresses but they are still much higher (+20% or more) than normal.

I have covered this in detail on my blog on RVTireSafety.
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Old 01-09-2015, 03:08 PM   #16
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Etrailer just wants you to sell you some new rims. A blanket statement saying all ST must be run at max pressure is just silly. You are going to build heat if your load exceeds the pressure rating for that load regardless of whether the tire is a C D or E. Running 65 in an E on a D load is not going to hurt anything, but it will give you a stronger tire.


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"A blanket statement saying all ST must be run at max pressure is just silly" is based on what Engineering analysis?

My advice is based on Finite Element analysis and well established vehicle and tire dynamic load formula.
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Old 01-09-2015, 09:26 PM   #17
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What does load formula have to do with anything if max pressure is always to be used period?


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Old 01-10-2015, 09:31 AM   #18
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Did you put them on the same rims that the C tires were on and what pressures do you have those tires at? Also do you find the E tires have less sway than the C tires?
Just saw your post, Yes to stock rims,
Just got to Florida 2000+ miles on the same C rims that we put the E Carlise's on before our trip. I ran them at 80#s. The trailer always tows without sway on either C's or E's with our 2500 Sierra GMC Diesel. I just like knowing I have the Carlisle Brand & stronger E tires.
I don't buy the 65# rating issue and feel 80#'s works best for the tire.
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Old 01-10-2015, 10:12 AM   #19
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Originally Posted by lbrjet View Post
A blanket statement saying all ST must be run at max pressure is just silly. You are going to build heat if your load exceeds the pressure rating for that load regardless of whether the tire is a C D or E. Running 65 in an E on a D load is not going to hurt anything, but it will give you a stronger tire.
===============
============================

Under inflating a ST tire will generate a lot of heat. When traveling I always check my tires cold and have maximum PSI (as rated on the tire) in the tires. Then when we stop I check the tires for over heating. Never yet had tires running hot on me. And that includes traveling through Texas- Arizona- Utah- Montana- Wyoming etc...
And it's not advisable to jump two ratings on tires with the same rims. Going up one lever is what the manufacturers allow ( ei, C to a D, D to a E etc..) but not a C to an E rating.

ST = Special Trailer tires are designed to take the lateral stresses placed on trailer tires, Truck tires aren't). If you want to see an exaggeration then when backing tightly into a camping spot get out and take a look at how the tires are angled. Looks like they will pop off the rims they are twisted so badly.
If you would like to understand ST verses LT tires then watch this video:



Happy trails,
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Old 01-10-2015, 10:47 AM   #20
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Originally Posted by Tireman9 View Post
"A blanket statement saying all ST must be run at max pressure is just silly" is based on what Engineering analysis?

My advice is based on Finite Element analysis and well established vehicle and tire dynamic load formula.
I doubt that you can show us any ST tire manufacturer that will recommend less than full sidewall tire pressures unless the Vehicle manufacturer will also do it. Who controls setting initial recommended tire pressures for OE tires? The vehicle manufacturer.

All tire users look at industry standards for proper servicing of their tires. If not, they should.

Some ST tire manufacturers come right out and tell us that their tires degrade as much as 10% per year. Airing such a tire to the load carried is just like asking for early tire failure. With all safety considerations satisfied youíre right to go up a load range and then use itís maximum potential.

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