GoodYear Marathon ST Tires and NHTSA

[gmw photos]

Originally Posted by CapriRacer

A couple of responses:



Ah, ...... Mmmmmm....... This isn't exactly correct.

Ya' see, part of what makes an ST tire an ST tire is that the tire trades off speed for load carrying capacity. Use a larger tire and the speed capability would increase. This holds true for LT tires as well.

Yes, yes, this isn't listed as part of the labeling on the tire or part of published standards, but it's there.

.

Are you saying that a given tire design is not rated to carry it's stated load at it's maximum speed at the specified pressure ?

thanks, geo

EDIT: ( to include the whole paragraph I wrote )

I said:
"Part of the reason I will not buy ANY ST tire is this bogus cheap azz nonsense of a tire only being good for 65 mph and 3 to 5 years. For just a few dollars more I can buy a LT that does not carry those handicaps."
....end quote.

[gmw photos]

Here is the example of what I did on my TT. It came from the factory with 14" load range C tires. Brand was Freestar. Load capacity was 1760 lbs @ 50 psi. The documentation I found on them said they were speed rated "J", which is apparently 100kph ( 62 mph ).
I replaced them with 14" load range D, Kumho. Capacity is 1874 lbs @ 65 psi. These are speed rated "Q" which is 160 kph ( 99 mph ).
I also replaced the valve stems with metal stems. I had them balanced which the factory did not do to the originals.

In my mind, even though I did not increase the diameter ( the Kumho is actually a fraction of an inch smaller in dia, but not much. About 2/10" ), I have improved my lot in life somewhat, for towing at normal highway speeds, which for me is typically between 55 to 60, but occasionally to 65 mph.

[RamblinManGa]

Hi from AZ . . . boy, no consensus on tires here !! never has been, best I can tell. I have GYM's on my Safari 25, with a date code of 2007. They were newly installed when I purchased the AS in 2010 and now have about 12 or 13,000 miles on them. They are properly inflated before EVERY move and covered otherwise. So, what's your point Craig ? NO failures, NO problems. As I contemplate new tires before next Summers long adventures, I'd buy them again without question if they weren't China made and may anyhow. New Carlisle's are re-engineered & American made, so maybe ?! Fun ain't it ! regards, Craig

[dstalzer]

Originally Posted by RamblinManGa

As I contemplate new tires before next Summers long adventures, I'd buy them again without question if they weren't China made and may anyhow.

Craig,
I installed a set of GYM's in August 2010 and they are stamped Made in USA. The original set of GYM'S from the factory were Made in Canada in 2004. I had one of the original tires blow out at 65 MPH when the temperature was close to 100. I figured the age of the tire and the heat most likely caused the blowout. If Goodyear had not moved their manufacturing back into the USA, after several years in China, I would have not purchased the Chinese GYM's.

I store my AS in my climate controlled garage and use it 30 to 50 days a year and tow between 60 and 65 MPH. So far the current GYM's have around 5000 miles on them, seem to be in great shape, do not loose air like others have reported and I hope to get a couple more years of use out out them.

Dennis

[Ben4762]

I've been running Goodyear trailer tires on 3 different trailers since 1977. I've never had a flat or blow-out. I did have an issue with one GYM tire that was 5 years old. The tread was starting to separate from the steel belts.

[CapriRacer]

Originally Posted by gmw photos

Are you saying that a given tire design is not rated to carry it's stated load at it's maximum speed at the specified pressure ?

thanks, geo

EDIT: ( to include the whole paragraph I wrote )

I said:
"Part of the reason I will not buy ANY ST tire is this bogus cheap azz nonsense of a tire only being good for 65 mph and 3 to 5 years. For just a few dollars more I can buy a LT that does not carry those handicaps."
....end quote.

No, I am saying that ST tires aren't restricted to 65 mph, IF they use more inflation pressure and/or they carry less load. IF LT tire were to be loaded to the same degree that ST tires are, they would be speed restricted as well.

In other words, part of the things that make ST tires St tires and LT tires LT tires is the speed vs load issue. In LT tires, the load is much less and the speed is greater.

Here, let me give you an example:

ST 235/85R16 Load Range E: Max Load 3640# at 80 psi. Max speed 65 mph

LT235/85R16 Load Range E: Max Load 3042# at 80 psi. Q speed rated ( 99 mph)

The ST tire is allowed to carry 600# more than the LT tires, BUT the LT tire has a higher speed capability.

Now, I am NOT arguing that there aren't problems with the current ST tires available on the market - there are, and the problems seem to be traceable to low quality designs - that is, those tires aren't benefitting from the latest technology.

BUT I am arguing that IF ST tires were redesigned, they WOULD perform as well as an LT tire. Why am I arguing that position? To make sure everyone understands that the label on the tire (the letters "ST") are NOT the problem. The confusion is understandable because the 2 things are present in these tires and the shortcut is easy to remember - but they aren't linked by the laws of physics and it is possible that some tire manufacturer will fix the problem by designing an ST tire the same way they design LT tires. I think there is some movement that direction - ala Maxxis - but it will take time for that to happen.

[Protagonist]

This website gives an indication of how to tell if a tire is American-made:
Where's My Tire Made | AmericanMadeTires.com

[gmw photos]

Originally Posted by CapriRacer

No, I am saying that ST tires aren't restricted to 65 mph, IF they use more inflation pressure and/or they carry less load. IF LT tire were to be loaded to the same degree that ST tires are, they would be speed restricted as well.

In other words, part of the things that make ST tires St tires and LT tires LT tires is the speed vs load issue. In LT tires, the load is much less and the speed is greater.

Here, let me give you an example:

ST 235/85R16 Load Range E: Max Load 3640# at 80 psi. Max speed 65 mph

LT235/85R16 Load Range E: Max Load 3042# at 80 psi. Q speed rated ( 99 mph)

The ST tire is allowed to carry 600# more than the LT tires, BUT the LT tire has a higher speed capability.

Now, I am NOT arguing that there aren't problems with the current ST tires available on the market - there are, and the problems seem to be traceable to low quality designs - that is, those tires aren't benefitting from the latest technology.

BUT I am arguing that IF ST tires were redesigned, they WOULD perform as well as an LT tire. Why am I arguing that position? To make sure everyone understands that the label on the tire (the letters "ST") are NOT the problem. The confusion is understandable because the 2 things are present in these tires and the shortcut is easy to remember - but they aren't linked by the laws of physics and it is possible that some tire manufacturer will fix the problem by designing an ST tire the same way they design LT tires. I think there is some movement that direction - ala Maxxis - but it will take time for that to happen.

Ok, now I understand what you are saying. Thanks for the clarification. So I take from your comments here that using a LT tire, that has sufficient load capacity ( with adequate reserve ) for the load we are placing on them, we are getting effectively the best of these worlds:
1. load capacity
2. speed rating
3. potentially higher build quality

....plus, although you didn't comment on it:

4. likely longer life ( from a strictly age standpoint )

Regarding running higher pressures in a ST tire to raise the speed rating, it is my understanding that GoodYear approves running up to 75 psi in a load range D Marathon. Doing so increases it's safe operating speed to 75 mph. However they do point out this does NOT increase the load carry capacity, and that you still must observe wheel ( and valve stem ? ) limits.

I should also point out in fairness to the chinese made ST tires that came on my little white SOB trailer, I ran them for a season, and none failed, even on some very hot all day runs. I attribute a least part of this to the fact that on my trailer, I have 3600 pounds sitting on the axles ( according to CAT scale ), and I had 7040 pounds of tire capacity, so in other words nearly double the load capacity. I am also religious about tire pressure ( I cheated them upward a little bit. Spec was 50 psi, I set them to 53 psi cold ) and I run pretty slow it sounds like compared to many users on this forum. I run 55 to 60 mph mostly.

By the way, to the comment above by r carl about Kumho being made in China, the company does have a plant in mainland china, but I am not certain what tires are made there. The Kumho's I have were made in Korea.

Thanks again for your clarification.

[jcanavera]

Originally Posted by CapriRacer

Bottomline: If the tire failure isn't reported, then it's like it never happened. While refusing to buy ST tires seems like a good tactic, in reality, it would take so long for the affect to be noticed and the numbers would be so small that I doubt it would work at all.

Yep I understand, but from an economic standpoint my immediate solution is to go with an LT rather than continue my cycle of replacing ST's every three years due to belt issues. #1 it saves damage to the trailer caused by the tire coming apart at speed. #2 while the cost of my 16" LT is higher, I consider that offset by the ability to get a minimum of 5 years of service from my LT's. #3 while I agree that it may be a blip on the radar to the tire manufacturers, why reward them and purchase a product that for many of us, has given us unsatisfactory service?

Jack

[Protagonist]

Originally Posted by jcanavera

#3 while I agree that it may be a blip on the radar to the tire manufacturers, why reward them and purchase a product that for many of us, has given us unsatisfactory service?

I don't think anyone is suggesting that you buy tires that you suspect will fail, just because you can report the failure.

BUT, if you have a tire that fails due to a manufacturing defect, by all means report it! No matter what brand it is, no matter whether it's on your trailer or your tow vehicle, or on any other vehicle you may own. Whether you bought the tire or it came with the vehicle or trailer.

Remember that big Firestone tire recall back in 2000? 6.5 million tires recalled and replaced, because enough failures were reported to cause a big enough blip on NHTSA's radar.

[BAB]

I dumped the 15" wheels and GYM's one month after I took delivery of my 2012 28' Intl. After just over a year (and about 14,000 miles) on my 16" wheels and Michelin LT's, I couldn't be more pleased. I did install a TPMS as well. After a four week trip to the Southwest, and just completing two weeks in the Northeast, my tires look brand new. While I don't habitually go over 62 MPH, there are a few times I've had to hit 70. Think this tire discussion (which has hundreds and hundreds of posts) has been very helpful to illuminate possibilities and allow owners to make their own choices. I made mine and appreciate all those who shared their experiences to allow me to make a more informed choice.

[CapriRacer]

Originally Posted by gmw photos

Ok, now I understand what you are saying. Thanks for the clarification. So I take from your comments here that using a LT tire, that has sufficient load capacity ( with adequate reserve ) for the load we are placing on them, we are getting effectively the best of these worlds:
1. load capacity
2. speed rating
3. potentially higher build quality

......

I see load capacity and speed rating as inversely related - and I see the third item as labeled incorrectly. There may be quality issues, but I think the real problem is design - as in what materials are supposed to be used where.

Originally Posted by gmw photos

........
....plus, although you didn't comment on it:

4. likely longer life ( from a strictly age standpoint )

..........

My ideas have been changing over time and I think the age issue is partially due to the fact that ST tires are more highly stressed and burn off the antioxidants more rapidly, partially because antioxidants are very expensive and likely to be used at reduced levels, and partially because the overall structure isn't as robust (boy, I hate that word, but nothing else fits!).

Originally Posted by gmw photos

......Regarding running higher pressures in a ST tire to raise the speed rating, it is my understanding that GoodYear approves running up to 75 psi in a load range D Marathon. Doing so increases it's safe operating speed to 75 mph. However they do point out this does NOT increase the load carry capacity, and that you still must observe wheel ( and valve stem ? ) limits......

This is part of the tire standard published by The Tire and Rim Association (TRA). It applies to ALL ST tires. In fact, this principle applies to LT tires - and you can extend it to ALL tires. It's part of the physics involved in tires.

Some types of tires have these sorts of things published so it is easy to see the relationship. But other types of tires are tightly defined that there isn't much wiggle room. For example: Passenger car tires are supposed to be used on passenger cars and they are designed to always to be used on paved streets, have a speed limit. Those are enough limitations that the load tables don't have special notes about differing speeds.

EXCEPT: They do have special notes for P type tires used on trucks - and P type tires used at very high speeds.

Originally Posted by gmw photos

.......Thanks again for your clarification.

You are quite welcome.