ST tires

[VWill]

You are not suggesting that a ST with a load index of 110 is different than a LT with a load index of 110, or even a P with the same load rating? I'm just trying to understand what you mean.

[Ag&Au]

Originally Posted by rp709

Which Michelin LT tires are the subject of a new recall?

I wouldn't call it new, but this is the only one I know of or could find on the internet.

Safety Recall : MICHELIN LTX M/S | Michelin Tires

Ken

[Bill M.]

I do not know what a Load Index is. What I am asking is if you took a GYM that is rated at 2500 or so lbs max load and tested it as a LT tire would it qualify for a 2500 lbs load rating as based on the LT testing. So, yeah, I am suggesting that the load ratings are not equavilent for the 3 types of tires mentioned. I think that load testing is done at different speeds for the tires resulting in higher ratings for ST tires than they would carry as if tested as LT or P tires.

[daveswenson]

Originally Posted by r carl

I can show you just how good ST tires are in an afternoon, we can put a set on my 3/4 ton truck and I will show you just how fast they can fail.

This is a ridiculous proposition. The forces a motorized vehicle places on a tire are nothing like the forces a trailer does. Let's be real.

[CapriRacer]

Originally Posted by Bill M.

I do not know what a Load Index is. What I am asking is if you took a GYM that is rated at 2500 or so lbs max load and tested it as a LT tire would it qualify for a 2500 lbs load rating as based on the LT testing. So, yeah, I am suggesting that the load ratings are not equavilent for the 3 types of tires mentioned. I think that load testing is done at different speeds for the tires resulting in higher ratings for ST tires than they would carry as if tested as LT or P tires.

Bill,

You've kind of hit the nail on the head!! ST tires have different operating conditions than LT tires - and P type tires are different than even those 2.

ST tires are for use on free wheeling trailer positions. The only torque applied to them is braking (and of course, the torque from rolling resistance, which is pretty small compared to braking on engine torque!). They are speed restricted to 65 mph.

LT tires are for powered vehicles. They are speed rated, with the minimum speed rating being about 99 mph. They have to provide cornering power for the vehicle.

P type tires (used on light truck application) are derated 10% for load carrying capacity. have speed ratings as low as 112 mph, and are for motorized vehicles.

Needless to say, the testing conditions for each type SHOULD be different for each type - and appropriate to each type.

So if I test the same SIZE tire, each type would have a different set of testing conditions - the ST tires being the most heavily loaded, but tested at a lower speed.

But if I test tires with the same load carrying capacity, then the ST tires will be the smallest.

Apples and bananas! You've got to be very cautious when doing comparisons to make sure you've accounted for all the differences.

[r carl]

Originally Posted by daveswenson

This is a ridiculous proposition. The forces a motorized vehicle places on a tire are nothing like the forces a trailer does. Let's be real.

But it is real, a ST tire cant hold up to what a LT tire can do.

[markdoane]

What do you mean by real? Have you done this experiment, or is this based on what you read on the internet.

[r carl]

Originally Posted by markdoane

What do you mean by real? Have you done this experiment, or is this based on what you read on the internet.

I wont argue about what should be obvious to you.

[daveswenson]

Originally Posted by r carl

But it is real, a ST tire cant hold up to what a LT tire can do.

Nor is it designed to. And an ST tire can handle side loads that an LT tire cannot.


That being said, it's pretty obvious that there have been some catastrophic failures with ST tires. I have had good results with my ST tires. Maybe I've been lucky, or maybe it's because I use a TPMS system and know that I have never run them under inflated. And get new ones every 4 years.

[r carl]

I don't think ST tires can't make you happy, I just think they could make you very unhappy.. I would hate to see anyone with a beat up wheel well.

[BoldAdventure]

According to my calculations, the dynamic inverse ratio to the circumference of the tire should create a multidimensional paradigm shift transversing the influx ratio of the torsion field when pressure is applied in the opposite wave front of the tires contact patch causing the ST tire to then decrease it's load capacity thusly being far inferior to wave front of the secondary particle emissions from the LT tire. When the wave front collapses the ST tire will then combust in a fit of rage.

Makes sense to me.

[John&Vicki]

Originally Posted by BoldAdventure

According to my calculations, the dynamic inverse ratio to the circumference of the tire should create a multidimensional paradigm shift transversing the influx ratio of the torsion field when pressure is applied in the opposite wave front of the tires contact patch causing the ST tire to then decrease it's load capacity thusly being far inferior to wave front of the secondary particle emissions from the LT tire. When the wave front collapses the ST tire will then combust in a fit of rage.

Makes sense to me.

Bada Bada Bing!

[Howard L.]

Research, rather than our forum talk is probably the best advice if a change to LT Tires is in mind. Here is one of many articles on the subject:

http://rvingwithmarkpolk.com/2012/11...s-vs-lt-tires/

My problem with the ST tires is the 65 mph limit. Here is a statement from ModYourRV.COM.

"While it is widely believed that ST tires are limited to only 65 mph, both Goodyear and Maxxis (and Power King Towmax STR also). advise":

"Industry standards dictate that ST tires are restricted to a speed of 65 mph unless a different speed restriction is indicated on the tire sidewall. If speeds from 66 to 75 mph are used, the tire cold inflation pressure can be increased by 10 psi without any decrease in load." Note: Wheel pressure maximum rating must be considered if overinflating the tires to run at higher speeds."

Since I have Maxxis ST s on our 30, I called them to see if the above was correct. Along with a verbal answer, an email below was sent:

(Hello Howard,

According to the Tire and Rim Association the inflation pressures and load specifications in general for any ST Radial trailer tires, regardless of the manufacturer, are designed and rated at 65 MPH. However, if the speed is higher than 65 MPH, the pressure and load need to be adjusted according to the following guidelines:
From 66 to 75 MPH – the tire inflation pressure needs to increase 10 PSI (not to exceed the maximum PSI the tire is rated for) but requires no load adjustment.
From 76 to 85 MPH – the tire inflation pressure needs to increase 10 PSI (not to exceed the maximum PSI the tire is rated for) and load should be reduced by 10%.
We hope this information is helpful. Thanks for your email and interest in Maxxis Tires.
Best Regards,

Your Maxxis Support Team)

In summary, with a Tire and Rim Association Load/inflation chart of air pressure and weights for your Maxxis or Goodyear ST (or LT) tires in your hand, look up what air pressure is necessary to match the weight of your trailer with the weight carrying capacity of the tires. An example: say, it is 70psi for my Maxxis when carrying the weight of my 30. I can add 10 psi. That brings the tire pressure to 80 and has not exceeded the sidewall max. I now have an up to 75 MPH tire. To 85 MPH, heaven forbid, you can do it, but first remove 10% of that weight from the trailer. Another way to do the numbers would be to find the tire's certified max wt. at 10 psi under the tire sidewall listed max--again from your tire chart. Multiply that times the number of trailer tires. If trailer weight is under that, you are good to add 10 psi (right up to the sidewall max) and drive at 75. If you're trailer weight is also 10% below that figured number, you've met the second criteria and you can try to kill yourself at 85.

You can also go back and figure what the minimum air pressure would be to safely carry the weight of your trailer (that's the number you must add 10 psi to and is all that is required to speed up to 75). If you run your tires at max psi, and max is above what you must inflate to, the rest is a weight safety margin.

I'm not trying to sell anything here. I just run the Maxxis 8008s on our 30 FC at 75 to 80 psi and find myself doing 70 mph sometimes on these TX hi-ways. Wanted to know where I stood doing that. The chart tells me that as low as 40 psi in those tires, they are still not at their load limits--on my trailer--not that I would ever run them that low. If you look up the ST 8008's speed rating, it's "Q", that's 99 mph.

Look up "Load/Inflation information" for your tires:
Goodyear, http://www.goodyearrvtires.com/pdfs/rv_inflation.pdf
Maxxis, http://www.maxxis.com/trailer/traile...nflation-chart

And so on for other brands. Sorry this so long, but thought good information.

Oh yes, checked with JC and the stock aluminum rims on my 2012 are good for 80 psi.


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[perryg114]

Remember more pressure equals more energy if the tire decides to explode. ST tires are stiffer because of higher pressures.

Perry

[Ag&Au]

Originally Posted by BoldAdventure

According to my calculations, the dynamic inverse ratio to the circumference of the tire should create a multidimensional paradigm shift transversing the influx ratio of the torsion field when pressure is applied in the opposite wave front of the tires contact patch causing the ST tire to then decrease it's load capacity thusly being far inferior to wave front of the secondary particle emissions from the LT tire. When the wave front collapses the ST tire will then combust in a fit of rage.

Makes sense to me.

Finally, something I can agree with.

Ken

[Ag&Au]

Originally Posted by Howard L.

Research, rather than our forum talk is probably the best advice if a change to LT Tires is in mind. Here is one of many articles on the subject:

............................................
see original post for text deleted for brevity.
...........................................
And so on for other brands. Sorry this so long, but thought good information.

Oh yes, checked with JC and the stock aluminum rims on my 2012 are good for 80 psi.


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When dealing with any engineered product, it is generally true that you can find ways to exceed the maximum rated loads to some degree with a low probability of failure. This is because sound engineering practice dictates a safety margin be designed in, However universally, when you exceed the stated maximum specifications, you will reduce the safety margin by some degree. My opinion is that it doesn't make sense to play lotto with safety margins, because the margins and what factors cause them to vary are generally unknown to the end user.

Ken

[Howard L.]

Originally Posted by Ag&Au

When dealing with any engineered product, it is generally true that you can find ways to exceed the maximum loads to some degree with a low probability of failure. This is because sound engineering practice dictates a safety margin be designed in, However universally, when you exceed the stated maximum specifications, you will reduce the safety margin by some degree. My opinion is that it doesn't make sense to play lotto with safety margins, because the margins and what factors cause them to vary are generally unknown to the end user.

Ken

And mounting LT tires, designed for powered vehicles, designed for good traction while maneuvering starting, stoping on a heavy weight towed vehicle is not playing lotto? I know I must be missing something in your analysis. Adding 10 psi to gain another 10 mph max speed is the guideline of the same Tire and Rim Association that set the basic 65 mph max speed for all ST tires in the first place. Hardly playing lotto. Again, the Maxxis ST tire quoted above is manufactured as a "Q" speed rated tire.


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[Ag&Au]

Originally Posted by Howard L.

And mounting LT tires, designed for powered vehicles, designed for good traction while maneuvering starting, stoping on a heavy weight towed vehicle is not playing lotto? I know I must be missing something in your analysis. Adding 10 psi to gain another 10 mph max speed is the guideline of the same Tire and Rim Association that set the basic 65 mph max speed for all ST tires in the first place. Hardly playing lotto. Again, the Maxxis ST tire quoted above is manufactured as a "Q" speed rated tire.


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Let me quote my own post:

Originally Posted by Ag&Au

When dealing with any engineered product, it is generally true that you can find ways to exceed the maximum rated loads to some degree with a low probability of failure. This is because sound engineering practice dictates a safety margin be designed in, However universally, when you exceed the stated maximum specifications, you will reduce the safety margin by some degree. My opinion is that it doesn't make sense to play lotto with safety margins, because the margins and what factors cause them to vary are generally unknown to the end user.

Ken

Definition of opinion

o·pin·ion
əˈpinyən
noun
noun: opinion; plural noun: opinions
a view or judgment formed about something, not necessarily based on fact or knowledge.

Based on that, I don't feel I need to defend what I said.

Now, had I said "It is a fact that...... etc." rather than "it is my opinion" Then perhaps I should feel a need to argue about it, but I didn't, so I don't.

Ken

[perryg114]

Everything is an opinion on here. Some are good some are bad and some are more informed than others.

Perry

[BoldAdventure]

Whats that saying about opinions and your bottom side?