ST vs LT tires

[Phil&Sher]

Well, in the end you pay your money and you take your chances, I suppose. For now I'm going to go easy on my GYM's, but based upon good reports from those who have so chosen, I'll switch to 16" Tredit T-02 wheels and Michelin LTX M/S (#25516) tires as soon as my GYM's need replacement.

[Phoenix]

It isn't hard to compare specs on ST versus LT tires. We looked up data for GYMs and looked for Michelin LT tires with the same (or very close) values on www.tirerack.com. Lots of tire info, data, survey and reviews on that site.

We only have one axle, so sidewall stress from pivoting isn't a problem. However, for multiple axles, this is done at parking speeds, so heat build-up isn't a factor. Also, stress can be reduced significantly by parking on dirt or gravel, or just sprinkling a little sand along the tire tracks.

Regarding actual plies used in sidewall construction, using "ply rating" to indicate relative sidewall strength has been a common practice with passenger car tires for decades. Very few "4-ply" rated passenger car and LT tires actually have 4 plies. Most have only two and some have only one, even from top rated manufacturers, like Michelin. In fact, the Michelin XPS Rib LT tires we now have on our Bambi are 10-ply rated, but they have only one ply in the sidewall. However, that one is steel.

Do I worry about tire failures anymore? -- No.

[slowmover]

Originally Posted by Phoenix

It isn't hard to compare specs on ST versus LT tires. We looked up data for GYMs and looked for Michelin LT tires with the same (or very close) values on www.tirerack.com. Lots of tire info, data, survey and reviews on that site.

We only have one axle, so sidewall stress from pivoting isn't a problem. However, for multiple axles, this is done at parking speeds, so heat build-up isn't a factor. Also, stress can be reduced significantly by parking on dirt or gravel, or just sprinkling a little sand along the tire tracks.

Regarding actual plies used in sidewall construction, using "ply rating" to indicate relative sidewall strength has been a common practice with passenger car tires for decades. Very few "4-ply" rated passenger car and LT tires actually have 4 plies. Most have only two and some have only one, even from top rated manufacturers, like Michelin. In fact, the Michelin XPS Rib LT tires we now have on our Bambi are 10-ply rated, but they have only one ply in the sidewall. However, that one is steel.

Do I worry about tire failures anymore? -- No.

Specs aren't always directly comparable between tire types. This is at the heart of the problem of wanting "better than" ST tires when trying to make comparisons to LT's.

Ply rating is out of date by a decade or two. Load Range is even slightly deceptive. Load factor ([k-factor] is where the action is as tires of otherwise same size and load rating can have a K-factor with real differences.

Again, it is easy to want better than ST tires. But it is another thing to get the right replacement in LT (and when moving up from 15" to 16") as trailer tires need to be run at maximum sidewall pressure for best performance.

A tire -- with otherwise good specs for replacement (this is not so obvious as a Tire Rack chart which is also my old way of doing it) -- not run at proper pressure which is full pressure, is a miss for best performance.

An IR thermometer, it turns out, is not an accurate assessment of tire temps. See TM9 on this. Same with TPMS.

The linked thread on RV.net (Revived Tire Thread in Tech Issues, today with over 300-posts, two tire engineers and some well-informed amateurs) goes into all this.

Nailing down the best tire for a TT now has better information, but it up ends some assumptions we've made around here (and on every RV forum).

.

[Gene]

Rednax, I don't understand why you say running a tire at full pressure is correct. Tire pressures (except maybe ST's) recommended by the manufacturers are usually far less than the tire's maximum. People are told to increase pressure when carrying a heavy load, though I expect few do on that uncommon time when they get a load of bricks at the brickyard.

I know Airstream, when they install Load Range E, 16" LT's, puts the maximum pressure in them. Some Forum members do the same, some don't.

I can understand that maximum pressure will make the sidewalls a bit stiffer and may decrease potential sway. Is that the reason you said it?

Gene

[Phoenix]

There appears to be a "quality/reliability" range in tires used on travel trailers. For highway travel, that appears to be GYMs at the bottom (least reliable) to Michelin XPS Ribs (somewhere near the top). See tire survey results and reviews for both of these tires on www.tirerack.com.

I think all of the analyses seem to center around how much (or how little) can one spend to get a tire that is both reliable and economical/cost effective.

After an expensive GYM blowout that damaged our Bambi, cost $450 in roadside assistance, and led to the purchase of three new ST tires (two of which subsequently failed), I skipped all of the analyses and just bought the best (and most expensive) tires I could find. While this is overkill for many, I only had to buy two wheels and tires, which is worth the peace of mind to me.

If I had to buy six wheels and tires, a little more analysis would have been justified; and I would most likely would have gotten a slightly less durable LT tire (like the Michelin LTX M/S2). However, I am personally not interested in putting another ST tire on my Airstream.

Just another opinion, but from personal experience, to be taken with a grain of salt...

[Gene]

Originally Posted by Phoenix

Just another opinion, but from personal experience, to be taken with a grain of salt...

Less than a grain.

There have been a number of such testimonies from Airstream and other RV owners about Marathons. We drive with less worry since we got the Michelins. They don't lose air like the Marathons did and wear better. We haven't ridden in the trailer, but Michelins are engineered to ride smoothly, so that's a plus too.

Gene

[slowmover]

Originally Posted by CrawfordGene

Rednax, I don't understand why you say running a tire at full pressure is correct. Tire pressures (except maybe ST's) recommended by the manufacturers are usually far less than the tire's maximum. People are told to increase pressure when carrying a heavy load, though I expect few do on that uncommon time when they get a load of bricks at the brickyard.

I know Airstream, when they install Load Range E, 16" LT's, puts the maximum pressure in them. Some Forum members do the same, some don't.

I can understand that maximum pressure will make the sidewalls a bit stiffer and may decrease potential sway. Is that the reason you said it?

Gene

Gene, I've been hearing this from the commercial guys for several years. And sorta ignored the pressure "fiat". My older practice/recommendations were load versus pressure as that was the big truck mantra (and who knows more than them, etc). But the experts (literal experts) and those old timers are emphatic about max pressure to maintain resistance against slip on our kind of trailers.

That RV.net thread is a good'un. Seriously good. See my recent thread on same for a few tidbits and link. Best tire thread anywhere, going back years.

.

[Gene]

I saw your new thread here about tires. It was interesting. I'm not sure I can stand another tire thread—I have a limit on how many tire threads I can follow at once.

Gene

[slowmover]

Ignore the ones here, then. They've been superceded. We're out of date as of a few days ago as a result of the Woodalls thread. I've already cleared my bookmarks and permanent files. Bye bye buggy whips.

Viable numbers for a proper match.

.

[tkowalyk]

Got the new LT tires installed this week. Looking forward to the increased peace of mind that will come with the LTs.

We had or Good Year Marathons for over 5 years, without incident.

[Ridgerunner3]

Originally Posted by tkowalyk

Got the new LT tires installed this week. Looking forward to the increased peace of mind that will come with the LTs.

We had or Good Year Marathons for over 5 years, without incident.

Very nice. The tires look like Michelins. Where did you get the wheels? I am probably heading the same direction on my next tires.

[dznf0g]

Originally Posted by Phil&Sher

Well, in the end you pay your money and you take your chances, I suppose. For now I'm going to go easy on my GYM's, but based upon good reports from those who have so chosen, I'll switch to 16" Tredit T-02 wheels and Michelin LTX M/S (#25516) tires as soon as my GYM's need replacement.

Good plan, but are these the OEM GYMs. If so, they are approaching their 5 year life span (by many accounts). Watch them closely.

[tkowalyk]

Bud,

They are indeed Michelin LTX M/S (LT225/75R 16 E) tires.

The Wheels are Tredit, a tire and wheel company in Indiana that Airstream gets supplies from. Make sure they are rated for Load Range E tires and have 0˚ offset.

Here is a link to the model I bought:

TR4 Mod

The right size is the 16x6.

Those tires are $241.36 each + mounting.
The tredit rims are $123.03 each including the center caps and lug nuts.

I bought 5 tires and a steel rim in the same style for the spare.

[Florida 55]

I purchased my 16" Sendel wheels from Performancetireplus.com . They are the same as the Tredit wheels. Current price (4/28/12) is $112.00. Performance carries all of the Airstream wheels including the Eddie Bauer and new Flying Cloud wheels. Shipping was fast, I had my wheels in 4 days. Do a web search for promotional coupons before ordering, you might get lucky and get a discount.

I bought 16" LTX MS Michelin tires for $188.00 plus tax mounted, balanced and installed from a local tire shop. The Michelins have performed well and hold the air pressure. I found myself adding air to the GYM's every 2 to 3 days.

[boondockdad]

Originally Posted by Phil&Sher

Well, in the end you pay your money and you take your chances, I suppose. For now I'm going to go easy on my GYM's, but based upon good reports from those who have so chosen, I'll switch to 16" Tredit T-02 wheels and Michelin LTX M/S (#25516) tires as soon as my GYM's need replacement.

This is exactly what we got. Liked the T02 better than the 'split-fork' style.
So far, so good.. only have about 1,000 miles on 'em
I think the real test will be Arches/Bryce/Zion trip this summer

Here's the OEM on left, and T02. Looks so much larger, but is only 1.1" larger in diameter.

[Phil&Sher]

Originally Posted by dznf0g

Good plan, but are these the OEM GYMs. If so, they are approaching their 5 year life span (by many accounts). Watch them closely.

Will do, but actually the GYM's I have on the trailer were manufactured in 2010, per the AS dealer where we bought the trailer and the date codes on all four tires.

[Phil&Sher]

Originally Posted by finalcutjoe

This is exactly what we got. Liked the T02 better than the 'split-fork' style.
So far, so good.. only have about 1,000 miles on 'em
I think the real test will be Arches/Bryce/Zion trip this summer

Here's the OEM on left, and T02. Looks so much larger, but is only 1.1" larger in diameter.

Beautiful! Nice comparison to the original....thanks.

[boondockdad]

And here they are rolling...
Please excuse the dirty trailer, I scaled before washing and waxing

[jasper2222]

Why not stay with the 15 inch tires and go with a 235 75 15 michelin m/s2. I do see another site where this is discussed. I am just in kind of delimina right now. Had a Marathon tire blow. Tire was 5 years old so need to change all tires. The m/s2 carries a weight rating of 2200 lbs. I have a 96 25ft excella. Would not these tires be good, instead of going to the added expense of new wheels and the Lt 225 75R 16 E rated tire?

Just need to do something in the next couple of days. marathon did not blow. Tread peeled off. Tire still had 50 lbs pressure.

thanks, richard

[bonginator]

Originally Posted by CrawfordGene

We changed to 16" Michelin LTX tires a couple of years ago and are very happy with them. We now have something like 24,000 miles on them and they are wearing much better than the Marathons did. I have been running 68 lbs. in them, but have increased it to 72 as the edges were wearing slightly faster than the centers. The Marathons lost air despite changing valve stems. The Michelins do not lose air.

We got the same wheels Moosetags did. They come from Tredit, a tire and wheel company in Indiana that Airstream gets supplies from. They are not the only company that has similar wheels. Just make sure they are rated for Load Range E tires and have 0˚ offset.

It is difficult to find a good LT tire in 15" for the size tire Airstream has been using in recent years, so we went to 16" wheels after measuring the space available about 100 times. We wanted Michelins because we have always had good experiences with them and they ride smoother than many other tires.

We got 5 new wheels, all the same, and rotate the spare around and will thus get more miles out of the set of 5 wheels and tires. The tire carrier has steel holders around it that can be bent outward to fit the 16" tire, but we carry it in the truck bed as it is easier to get in and out and easier to check air pressure.

Some people use the Michelin Rib tire. This is a tire designed for commercial trucks and the carcass will last a very long time as the tire is meant to be retreaded. It has steel cord in the sidewalls and appears to be a very firm tire, perhaps too much so. I expect the carcass will last well over 100,000 miles and seems like overkill to me. The firmness of the sidewalls may make it harder to back up at extreme angles because of the inability of the tire to bend sideways until it skips. The LTX looked like the best deal—it should last 50,000 miles or more and we will probably get to that in 5 years of use when it is time to get new tires anyway.

ST tires are not speed rated. It is suggested not to go more than 65 mph with them, and if you go faster to increase air pressure. Most speed rating is done because of gov't regs on passenger cars. I don't believe LT tires have to be speed rated, but many are and the ratings are in the 90's or higher. It's rough not to be able to tow at 120 mph, but you have to accept certain limits to have an Airstream.

Gene

Gene- time for us to get new tires on our 23 fb se. Would you pm me with the exact tire numbers you bought? I'd like to contact your seller about getting a set after measuring our wheel well.

Sandy