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Old 10-16-2013, 12:20 PM   #15
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Originally Posted by 28Argosy View Post
Gosh this stuff is going over my head. I am sure all this will make sense to hubby, but meanwhile - I am lost...
The current tires on our Argosy 28 are Good Year 7.00-15LT. "Trailer High Mileage Tubeless White Walls"...
Opinions?
What is the DOT serial date for your tires? That size is an old size.
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Old 10-16-2013, 12:27 PM   #16
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snip

Part of what goes into determining the load carrying capacity is speed and the load tables are set up for the speed of the intented service. If you dig around the tire standards, you will repeatedly find references to changes in load carrying capacity for differences in speeds. For example, if you want to raise the speed restriction of an ST tire from 65 mph to 85 mph, you need to increase the inflation pressure 10 psi and reduce the load by 10% (which has the same effect as increasing the inflation pressure another 10 psi.)

snip
Capri, Need to be careful with the speed adjustment info. It can easily be misinterpreted. I had a discussion with GY Cust Service and was told that their tech bulletin only addresses the +10 mph with a +10psi and does not allow for an increase in pressure above the pressure associated with the max load. I am still trying to get something in writing from GY.

Also even if GY says it is OK to do this you should not use a GY bulliten and apply the information to an other brand. This would be like using Michelin unique load/infl info on a Cooper brand tire.
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Old 10-21-2013, 09:18 AM   #17
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Originally Posted by Tireman9 View Post
Capri, Need to be careful with the speed adjustment info. It can easily be misinterpreted. I had a discussion with GY Cust Service and was told that their tech bulletin only addresses the +10 mph with a +10psi and does not allow for an increase in pressure above the pressure associated with the max load. I am still trying to get something in writing from GY. Also even if GY says it is OK to do this you should not use a GY bulliten and apply the information to an other brand. This would be like using Michelin unique load/infl info on a Cooper brand tire.
Tireman,

That GYM service bulletin is here: http://www.tirerack.com/images/tires...plications.pdf

Industry standard clearly show tires developed for specific service ALL meet the same load/inflation specifications. When the tire service (use), size, and top load ratings are the same, the chart of loads vs inflation pressures are identical. Brand has nothing to do with it.
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Old 10-22-2013, 06:26 AM   #18
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Originally Posted by farrel509 View Post
Tireman,

That GYM service bulletin is here: http://www.tirerack.com/images/tires...plications.pdf

Industry standard clearly show tires developed for specific service ALL meet the same load/inflation specifications. When the tire service (use), size, and top load ratings are the same, the chart of loads vs inflation pressures are identical. Brand has nothing to do with it.
I think what Roger was getting at was that, while the issue of what affect speed has on a tire's performance may be independent of brand - kind of a Physics sort of thing - the brand determines how the warranty is affected and what the brand feels comfortable with as far as recommendations are concerned. Straying outside the parameters stated by the tire manufacturer would affect what testing they would have done to verify the performance envelope and how the warranty is applied.
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Old 10-22-2013, 02:29 PM   #19
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Originally Posted by farrel509 View Post
Tireman,

That GYM service bulletin is here: http://www.tirerack.com/images/tires...plications.pdf

Industry standard clearly show tires developed for specific service ALL meet the same load/inflation specifications. When the tire service (use), size, and top load ratings are the same, the chart of loads vs inflation pressures are identical. Brand has nothing to do with it.
Yep it is true that TRA does allow all tires without a "Service Description" to exceed the default 65 mph speed limit. This per my discussion with an engineer at TRA about an hour ago.
The problem is that Goodyear will tell you not to exceed 75 on their ST tires even though the "standards" allow operation to 85mph, so you really need to be sure you fully comprehend what you are reading when you make broad statements about adjustments that can be made outside the normal conditions.

Many times there things you can do but that doesn't mean it is the wise thing to do. You may be able to run your engine above the "redline" but I don't think that is wise.
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Old 10-22-2013, 06:27 PM   #20
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Tire pressures for RV trailer tires (any design) are just not arbitrary. The trailer manufacturers are directed by the DOT to set the correct recommended (cold) tire pressures and display them on the trailer's certification label/tire placard and in the vehicle's owner's manual.

I attend two to four large RV sows every year. In the past two - three years I've never seen any size RV trailer with recommended tire pressures below the maximum allowed on the OE tire's sidewall. I'm sure there is valid reasoning for that condition. RV trailers are notoriously over loaded.

The regulations for tire selection and fitment to the RV trailer axles differ considerably from the automotive industry. Trailer tire manufacturers tout their tires as always needing full sidewall pressure and that it's not harmful to the tires. Their load inflation charts are intended to assist vehicle manufacturer's in their tire fitment selections and nothing else.

I have not figured out how to use a load inflation chart on tires that are already using maximum tire pressures. NHTSA allows tire pressures to be lowered for special conditions. Normally it's never going to be recommended to use less tire pressure than that which has been recommended for the Original Equipment tires. Remember, I'm writing about RV trailer tire fitments. Do not confuse that information with motorized RV tire fitments.

BA
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Old 10-22-2013, 06:57 PM   #21
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ST versus LT

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Originally Posted by CapriRacer View Post
[FONT=Arial][SIZE=3]

I'd also recommend using no more than 85% of the rated capacity of the ST tires.
CapriRacer, would you give us your opinion on the rush to replace ST tires on Airstreams with LT tires?
I have had good service from ST tires through years of Airstreaming. I have MAXXIS ST Load Range E tires on my 2007 Classic 30, and I couldn't be more pleased.
DANGER! This is a highly emotional topic for some!
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Old 10-22-2013, 07:03 PM   #22
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CapriRacer, would you give us your opinion on the rush to replace ST tires on Airstreams with LT tires?
I have had good service from ST tires through years of Airstreaming. I have MAXXIS ST Load Range E tires on my 2007 Classic 30, and I couldn't be more pleased.
DANGER! This is a highly emotional topic for some!
Hi Ken,
I'm not Capri, but I will toss a comment into the ring on this. I think you can answer your own question about whether it's worth taking off ST and installing LT.

Ask yourself this question: do you think ST tires are "as good", and last "as long" as LT tires ?

If, in your mind, the answer is yes, then possibly it makes sense to continue using ST tires since they cost fewer dollars to buy.

If the answer is "no", then perhaps it might make sense to use a LT tire.
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Old 10-22-2013, 07:29 PM   #23
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Hi Ken,
I'm not Capri, but I will toss a comment into the ring on this. I think you can answer your own question about whether it's worth taking off ST and installing LT.

Ask yourself this question: do you think ST tires are "as good", and last "as long" as LT tires ?

If, in your mind, the answer is yes, then possibly it makes sense to continue using ST tires since they cost fewer dollars to buy.

If the answer is "no", then perhaps it might make sense to use a LT tire.
Just put 16" wheels and Michelin LT's on our 2005 Classic 30 today. I was relieved to find everything fit just fine and the wheels look pretty sharp!

I can't say I ever had really bad experience with ST tires although I did have three out of four GYM's all start throwing tread half way across Texas on our previous non-AS trailer.

I put that down not so much to defective tires but to my own lack of awareness!

At that time I figured that as long as I had decent tread and no sidewall cracks, I was good to go! Those tires were likely ten years old! Now I change tires every five years.

However, I liked the load capacity and speed rating of the 16" LT tires as well as the ready availability of good quality replacements, and the good reports that people I respect on this forum had given.

As well, the fact that the Airstream factory are now offering 16" LT Michelins as an option swayed me some, so I have joined in!

Hoping it works out well! Will be heading south to test them out next Feb!


Brian.
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Old 10-23-2013, 06:43 AM   #24
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Originally Posted by Alumaholic View Post
CapriRacer, would you give us your opinion on the rush to replace ST tires on Airstreams with LT tires?
I have had good service from ST tires through years of Airstreaming. I have MAXXIS ST Load Range E tires on my 2007 Classic 30, and I couldn't be more pleased.
DANGER! This is a highly emotional topic for some!
Yes, it is a very emotional topic - one that generates lots of acrimony.

I see 4 problems:

1) There are trailer manufacturers who do not do a good job of sizing tires. I can't say for sure that Airstream is not one of them, but there are indications they are doing a good job. I just don't have enough information about the past to make a judgment.

2) People who are not familiar with the demands RV'ing makes on vehicles - and tires - will neglect to check the tires and in particular, the inflation pressure. Some aren't even aware that the tires on trailers require much more inflation pressure than the tires on their tow vehicles.

3) Trailer tires are manufactured by what I call "Third Tier" manufacturers (or using Third Tier equipment). By "Third Tier", I mean not mainstream or specialty manufacturers. This means that the technology employed is behind the times and not up to par with today's expectations.

This also means that there is no feedback system to inform the tire manufacturer or the trailer manufacturer that the tires are not performing as well as they should. Without that kind of feedback, not only don't they know there is a problem, but they would have no way of judging if any changes affect the performance.

There are 2 notable exceptions - Goodyear and Maxxis. Goodyear certainly has the expertise and the dealer network, but I wonder about whether they have perceived the problem - and if they have, have they made changes. It's hard to tell.

Maxxis, on the other hand is a fairly aggressive tire manufacturer who is struggling to get out of the Third Tier box and enter the world market as a serious player. In the US, they just don't have the dealer network, so I wonder how effective their feedback system is working for these types of tires.

4) The 3 above conditions set the stage for issues. If all three of these was as it should be, then there would not be a need to look for alternatives. Allow me to point out that car manufacturers and truck manufacturers don't seem to have these issues - as do even third tier tire manufacturers of tires for these pieces of equipment.

That means that people start looking for alternatives. The simple thing to do is to change tires - and LT tires just happen to be there. What frequently gets lost in the conversation is that there are usually several changes that take place when the changeover is made, but the "fix" is usually attributed to just one attribute - the letters "LT" on the sidewall.

And one last point: It is difficult to diagnose a tire failure - and many "tire failures" have origins in road hazards. The tire gets blamed for many things that are not its fault. So the water is plenty muddy and it can be hard to discern a real tire failure - one that requires some changes at the design end of things.

Add to this the human tendency to seek a simple answer, and you get many opinions - some misguided.

Further add to this some mis-information that is out there, and you have a "perfect storm".
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Old 10-23-2013, 12:31 PM   #25
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Tire pressures for RV trailer tires (any design) are just not arbitrary. The trailer manufacturers are directed by the DOT to set the correct recommended (cold) tire pressures and display them on the trailer's certification label/tire placard and in the vehicle's owner's manual.

I attend two to four large RV sows every year. In the past two - three years I've never seen any size RV trailer with recommended tire pressures below the maximum allowed on the OE tire's sidewall. I'm sure there is valid reasoning for that condition. RV trailers are notoriously over loaded.

The regulations for tire selection and fitment to the RV trailer axles differ considerably from the automotive industry. Trailer tire manufacturers tout their tires as always needing full sidewall pressure and that it's not harmful to the tires. Their load inflation charts are intended to assist vehicle manufacturer's in their tire fitment selections and nothing else.

I have not figured out how to use a load inflation chart on tires that are already using maximum tire pressures. NHTSA allows tire pressures to be lowered for special conditions. Normally it's never going to be recommended to use less tire pressure than that which has been recommended for the Original Equipment tires. Remember, I'm writing about RV trailer tire fitments. Do not confuse that information with motorized RV tire fitments.

BA
You are correct. The only use for Load Infl tables for TT is to confirm you are not overloading your tires after getting the individual loads confirmed on calibrated scales. I would suggest you underload your tires by at least 10% if not more.
The tables can be of use if/when you decide to up-rate your tire load capacity with a new size.
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Old 10-23-2013, 03:03 PM   #26
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Status: New Wheels and Kumho LTs on the trailer now along with a set of Centramatics. Also shown is the last "blowed up" GYM. Note I have put some air in it to demonstrate how the tread separation causes a bubble under the tread. When the tire goes flat, it make it look like the tire was under-inflated, which it wasn't. All but one of my GYM failures looked like this one except the one that blew the bubble in the sidewall.
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Old 10-23-2013, 03:48 PM   #27
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The pic above on the right of the tire shows other issues that have been going on long enough to cause a wear pattern. (In addition to the bulge in the top portion of the pic.

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Old 10-23-2013, 07:01 PM   #28
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My last set of ST tires had wear pattern very similar to what I think I see in the picture (apart from the bubble).

Significant wear on both sides not the centre. In checking various websites showing different types of tire wear, I assumed that I had caused the problem by running the tires at too low a pressure.

But in your case, you said low pressure was not an issue.

Mine were completely worn out after about 2-1/2 years and 14,000 miles. Only 1mm tread depth left on each side.

For the first year I had run them at about 55 psi, then 60 psi for the balance of the time.

Guess I might have been smarter to run them at the max - 80psi - as one of the earlier posts suggests.

I will probably try that with my new tires starting with our first trip this winter.

I had the tire shop air them up to 75 psi, but it sounds like maybe I should bump them right up to 80. (They are LT's).

Brian.
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