02/12: New Tire Discussion on Woodalls: LT versus ST and more.

[slowmover]

Originally Posted by eleighj

After reading the entirety of the Woodall thread along with this one and reviewing the spreadsheet provided by Barry’s Tire Tech; it seems for our one axle trailer which is rated at 4300# GAWR and 4500#GVWR that we can either continue using ST225/75R15 LRD GYMs or upgrade to LT225/75R16 LRE. I do not think that going the “intermediate step” of going to a ST225/75R15 LRE wheel and tire combination would be cost effective; better to pay the price once. Also; it looks like to me that if you stay with the GYMs; you need to be prepared to trade every 3 years or 15,000 miles whichever comes first.

Lewster was pretty much right on the money when he posted this back on 3/1/2007; http://www.airforums.com/forums/f438...tml#post442750.

We will be upgrading to the LT225/75R16 LRE wheel and tire combination shortly. Serious piece of mind for us one axle folks.

Ed

Hi, Ed. Kudoes on making ones way through that lengthy thread (due to post numbers and links) and for adding the link from a resident wise man. Bob Thompson has a lengthy thread recently revived on the BFG Commercial T/A. While the Load Rate E is a stiff sonuva (due to running max psi) I hope it works for you. Going to 16" does seem the right way.

[eleighj]

Originally Posted by REDNAX

Hi, Ed. Kudoes on making ones way through that lengthy thread (due to post numbers and links) and for adding the link from a resident wise man. Bob Thompson has a lengthy thread recently revived on the BFG Commercial T/A. While the Load Rate E is a stiff sonuva (due to running max psi) I hope it works for you. Going to 16" does seem the right way.

Rednax:

One thing I noticed in Lewster’s post was that he was running his BF Goodrich Commercial T/A tires @ 65 PSI. Whatever tires we get we will run at the specified PSI for the tire. As for making my way through the RV Forum thread; as I deal with a lot legal writing every day; it was refreshing.

Ed

[slowmover]

There are those -- and I was among them -- who will run TT tires at a pressure less than sidewall maximum, more reflective of load (as we would with the TV). But, as you note, the sidewall max is now the minimum. Thus, ideally, the correct Load Range (Load Index, more accurately) be chosen.

[Gene]

Originally Posted by eleighj

Rednax:

One thing I noticed in Lewster’s post was that he was running his BF Goodrich Commercial T/A tires @ 65 PSI. Whatever tires we get we will run at the specified PSI for the tire. As for making my way through the RV Forum thread; as I deal with a lot legal writing every day; it was refreshing.

Ed

The specified psi varies according to the weight it supports. Specified does not equal maximum psi—the number printed on the side of the tire.

It is best to consult tables for a specific tire to show how much weight it supports at different pressures. You could vary it according to how much heavy the trailer actually is or go with the maximum gross weight of the trailer. Then tinker with it according to tire wear.

Gene

[slowmover]

Gene, you'll want to familiarize yourself with that thread. As your fellow attorney will indicate, you find yourself in opposition to two professional tire engineers by any longer advocating less than sidewall maximum. One may quibble over this, I leave to others what they do, but a few things in re TT tires now seem well set.

As to the TV tires, load versus pressure is still operative.

New info, the reason I started this thread.

[Cracker]

I asked this question a long time ago (---around 2006) - but never got an answer:

Correct Pressure??
This discussion finally came around to my question! During my factory vist, Airstream replaced my original Goodyear Marathon tires, load range "C," with new Goodyear Marathon, load range "D" tires. As Porky pointed out, the capacity of the "D" tires is 2,540 lbs at 65 psi, as opposed to 2,150 lbs at 50 psi for load range "C" or "D." Airstream originally recommended that the tires be inflated to 50 psi for my 2000 30' Excella. Accordingly, in order to achieve the softest ride, I would assume that the lower 50 psi pressure is still correct? I don't believe that Airstream is willing to arbitrarily increase my CCC by 1,560 lbs!
__________________
Cracker

None of the current discussions have provided a definitive answer either - however, I continued to run the tires at 50 psi for the next 6 years (---as per my previous comments herein) without incident. So, was my assumption correct???

[Phoenix]

Data from the Airstream Tire Failure Poll seems to imply that owners with Load Range C tires run 50 psi, and most with Load Range D and E tires run 65 psi. While this can't be confirmed directly, the numbers seem to support this. It appears that only a couple of owners run more than 65 psi, and I am one of them.

Discount Tire and Costco both recommended running 80 psi in the Load Range E tires on our Bambi, especially since summer temperatures frequently exceed 110 degrees.

Our Airstream does not ride hard on 80 psi tires. I suggest you try riding in yours with 50 psi. Then, then raise the pressure to 65 psi to see if there is any difference. However, you may not have any problems due to your lower ambient temperatures.

[Gene]

Rednax,

I'm trying to avoid reading the other thread and take what others say about it into consideration. We were running 68 psi in Load Range E tires, but have increased it to 72. For what it is worth, that's half way between 80 and 65, a statistic that has little relevance, I suspect.

I do not understand why auto and truck companies recommend less than sidewall maximums for vehicle tires if the tire engineers on that other thread recommend otherwise for trailers. Maybe if I read the thread, I'd know, but I should be doing other things right now and maybe I'll never know.

Gene

[eleighj]

I have some questions / thoughts on this issue:

1. Should the axle(s) alignment, balance, etc. be checked annually; same as with a vehicle?
2. Weighing your trailer often matters! There is a lot of data in the owner’s manual about weight and distribution; almost need to learn about weight and balance same as pilot. We will be doing this chore, again, this weekend as we have just had the new Airstream bike rack attached!
3. For use one axle guys redundancy may be a necessity. If you read the owner’s manual it has the following quote:
   “In an emergency you may remove the flat tire. The independent suspension of the Rubber Torsion Axle allows four wheel units to be safely towed on three wheels for a short distance (100 miles maximum) and only at a low speed (30 MPH).” Does not work for us!
   I know from posts by other single axle owners such a Phoenix and Lewster (formerly) a there is a high degree comfort in going to a LT225/75R16 LRE tire; max tire pressure discussions aside.
4. Are GYMs perceived to be somewhat inferior due the supposed lack of “latest” technology being used in their manufacture? Just wondering.

Last but not least I am not a lawyer; just have a lot of them working for me; so I have learned the lingo and thought process. Scary!

Ed

[Gene]

Originally Posted by eleighj

[FONT=Times New Roman][SIZE=3][*]Are GYMs perceived to be somewhat inferior due the supposed lack of “latest” technology being used in their manufacture? Just wondering.[/LIST] Last but not least I am not a lawyer; just have a lot of them working for me; so I have learned the lingo and thought process. Scary!

Ed

Perception is not often based on facts. So, perceive this as you will: my perception is that the technology for a better tire exists, but the manufacturer can choose not to use it to save money and have comfort that for the moment, people are still buying the product.

The other 3 questions are not as easily answered. Checking things like balance, etc., should be periodic (vague answer). Using Centramatics gives a slack on balance. Alignment can be checked by using a tire depth gauge every couple of months. You don't have to weigh the trailer if you know how much the things you put in it weigh—we did that early on and came put much lower than capacity. This is not the way most people do it. I would not want a single axle trailer and if I owned one, would get the absolute best tires for the job. I have done that anyway (in my perception, hopefully fact based).

You are lucky, Ed, to be surrounded by so many lawyers who have taught you logic and the mysteries of law. In fact, my wife has listened to me so well that she now uses my arguments against me. I have to remind her I have training and licenses she does not. And I am a licensed notary public as well. None of these arguments, admittedly not grounded in pure logic, convince her. I was cursed to marry a very smart woman. She does leave tire selection to me, however, proving once again she is too smart to be bothered learning all the tire information when she has me to do it.

Gene

[Phoenix]

Gene makes good points. It seems it's always about money. Why sell travel trailers with $290 tires on them when $115 tires will do. The more expensive tires will only jack up the price, and owners will complain about replacing tires with tread still left on them. That way, the decision to upgrade to more expensive tires is left up to the owner, who can decide how much he wants to spend on the next set.

With only one axle and a history of tire failures, the decision was easy for me; and no detailed scientific analysis was necessary: Just buy the best tires made. Fortunately, we only had to buy two of them...

[slowmover]

Gene, the magic term for TT's is:

side slip angle

and the portal to usage differences, one might say, between TT's and TV's in re tires.

[slowmover]

Originally Posted by Cracker

I asked this question a long time ago (---around 2006) - but never got an answer:

Correct Pressure??
This discussion finally came around to my question! During my factory vist, Airstream replaced my original Goodyear Marathon tires, load range "C," with new Goodyear Marathon, load range "D" tires. As Porky pointed out, the capacity of the "D" tires is 2,540 lbs at 65 psi, as opposed to 2,150 lbs at 50 psi for load range "C" or "D." Airstream originally recommended that the tires be inflated to 50 psi for my 2000 30' Excella. Accordingly, in order to achieve the softest ride, I would assume that the lower 50 psi pressure is still correct? I don't believe that Airstream is willing to arbitrarily increase my CCC by 1,560 lbs!
__________________
Cracker

None of the current discussions have provided a definitive answer either - however, I continued to run the tires at 50 psi for the next 6 years (---as per my previous comments herein) without incident. So, was my assumption correct???

The definitive answer is to run TT tires at sidewall maximum. Thus the difficulty of trying to get a better tire than ST but otherwise a commensurate load capacity with adequate reserve.

Truly, this is best done in wheel-by-wheel weighing as it can be that one wheel of a four wheel tandem axle trailer is carrying 30% more weight than any other. An axle average (as many of us have used) is helpful, but not definitive.

Thus, the link above to (tire engineer) Barry Smith's TIRE TECH page on ST tires is recommended. From the charts included, make ones selections and conversions.

[slowmover]

Conversion chart:

Barry's Tire Tech

[Cracker]

[/QUOTE]None of the current discussions have provided a definitive answer either - however, I continued to run the tires at 50 psi for the next 6 years (---as per my previous comments herein) without incident. So, was my assumption correct???[/QUOTE]

Even with the above history, and all of my previous history, I'm still curious enough to want to weigh my individual wheels - if I can locate a scale that will acommodate me. I've never noticed whether or not the truck depot scales I normally go to are wide enough to permit putting one side of the trailer on the scales at a time. The only reason for not simply inflating the "D" tires to 65 psi is the fact that my Airstream shows no sign of stress and seems to ride very smooth. We were even surprised on one trip to find an open glass of coke that we left on the table during a lunch stop in Bennington, Vermont still sitting there, unspilled, when we arrived home in Pittsfield, Maine - and this on secondary roads while being towed by a GMC dually!

[howco]

well, I read this whole thread.
One week later my PHD came in the mail.
PHD stands for, "Piled Higher and Deeper."

Now I'm really confused.......

[Kosm1o]

Originally Posted by howco

well, I read this whole thread.
One week later my PHD came in the mail.
PHD stands for, "Piled Higher and Deeper."

Now I'm really confused.......

I'm with you. The tire discussions are never ending. I didn't buy a TT only to worry about all the issues mentioned in this and the many other threads about tires. I read , I decided, I bought. And just like my cars and truck, I don't want spend a lot of time worrying about it or second guessing my decision.

[slowmover]

Originally Posted by Kosm1o

I'm with you. The tire discussions are never ending. I didn't buy a TT only to worry about all the issues mentioned in this and the many other threads about tires. I read , I decided, I bought. And just like my cars and truck, I don't want spend a lot of time worrying about it or second guessing my decision.

Hell, none of us do. That's unfair to the subject itself, not to mention the participants in these discussions. The point to this thread is that, for the price of admission -- a reading of a thread on WOODALLS shortened by only reading about four of the contributors -- is the emphais given information about tires in general, and ST in particular, by two tire engineers who took it upon themselves to help clear the air around what constitutes reliability, first, and how to get above that bar in light of continued problems with outdated, sub-par tires while at the same time buying no more tire than is necessary as replacement.

Click on the above link, and gee whiz, all the work is done for you. The risk of failure is now greatly diminished. Now, on what subject do you have something constructive to add? Or, in light of your post, could that exist given its premise?

.

[Gene]

Originally Posted by Kosm1o

The tire discussions are never ending.

Absolutely. Investigating never stops. Answers can be elusive.

I am tired of these discussions, but quite literally a lot is riding on it. I make decisions, think about them, do not worry, move on down the road, read more.

Rednax comforts me because he keeps looking and maybe someday he will convince me to add more air to my tires.

Gene

[sailors]

OK everybody. I have viewed all posts and am still confussed. We have to replace tires on our 2006 20' Safari tomorrow. This will be the second time in 5 1/2 years. They are ST225-75R15. We spend our summers in Wa. state and winters in Az. What tire should I get?