ST vs LT tires

[Wayne&Sam]

Originally Posted by pattonsr

If the JC Service Center does the 16" tire installation, do they balance the tires before mounting them?

I had mine shipped to me from JC. They came balanced.

[Phly36]

I've got 4 - Cooper Road Master 7.00-15LT tires on our 1976 24' Argosy. Anybody know anything about these tires?

[Phly36]

I see that they have a max load limit each of 1,720lbs. Should be OK for our uses. I just don't know how old they are . . . We've owned "The Goose" for a year & are living in her full time. And, I might add, loving it!

Phil & Judith Meyer

[DFlores]

The original post asked st or lt.....I am experimenting with my box trailer. I purchased a set of four Maxxis M8008's in San Antonio's Peterson Tire Warehouse. I found that buying from the warehouse saved me some money. Gary Peterson was a great help.

These are ST tires, since my box trailer will only go 14" wheels. I will post any failures, flats, etc. maybe others can do the same for other brands and sizes.


Wish me luck

[tvanwave]

Originally Posted by Phil&Sher

I read somewhere that ST trailer tires are rated for 65 MPH and LT truck tires are rated for 95 MPH. I also read a post on another forum from a guy who was having lots of tire problems on a heavy fifth-wheel, even though he was cautious about his weight and speed. He switched to from 15" ST's to 16" LT's and his problems disappeared.

ST Goodyear Marathons are speed rated R = 106mph

[Gene]

This article posted on Discount Tire's website disagrees with a speed rating of 106 mph: Trailer Tire Facts - Discount Tire

Actually my understanding is that ST tires are not required to be speed rated at all. The recommendation is that speed not exceed 65 if you inflate them at 65 psi. Goodyear has stated on its website that you can increase both inflation and speed to 75: http://www.tirerack.com/images/tires...plications.pdf . Any manufacturer may do the tests for speed rating if it wishes. In another place on the Goodyear website, it states the ST speed rating is 65.

Gene

[azflycaster]

Maybe that was KPH.
65 MPH = 104.6 KPH which is very close.

[Phil&Sher]

Originally Posted by tvanwave

ST Goodyear Marathons are speed rated R = 106mph

Good Luck

[BigAl]

My understanding is that the trailer tires are not rated but passenger tires are.
The Goodyear marathon has a max speed rating of 65 MPH. If your inflation for your trailer weight is below the max pressure rating of the tire then if you inflate ten pounds over that pressure you can increase max speed by 10.
Go to Goodyear website and confirm this for your self.
Al

[Phil&Sher]

Goodyear Product Service Bulletin #2011-13
May 18, 2011

TO: Goodyear Company Owned Outlets, Goodyear Contract Dealers,
Goodyear Canada Inc. Dealers

Subject: Tires for Trailer Use Only: General Information (replaces PSB 2006-06)

This bulletin provides important information to help your customers obtain the best performance from "Special Trailer" tires. Please review the following important points with your trailer tire customers.
Special Trailer ("ST") Tires
Goodyear Marathon trailer tires are widely used in a variety of towable trailer applications and are designed and branded as "ST" (Special Trailer) tires.

• Industry standards dictate that tires with the ST designation are speed rated at 65 MPH (104 km/h) under normal inflation and load conditions.
• Based on these industry standards, if tires with the ST designation are used at speeds between 66 and 75 mph (106 km/h and 121 km/h), it is necessary to increase the cold inflation pressure by 10 psi (69 kPa) above the recommended pressure for the rated maximum load.

o Increasing the inflation pressure by 10 psi (69 kPa) does not provide any additional load carrying capacity.
o Do not exceed the maximum pressure for the wheel.
o If the maximum pressure for the wheel prohibits the increase of air pressure, then the maximum speed must be restricted to 65 mph (104 km/h).
o The cold inflation pressure must not exceed 10 psi (69 kPa) beyond the inflation specified for the maximum load of the tire.

[Kosm1o]

At this point in the GM st tire discussion and other st tire discussions , does a speed rating have any believable relevance? I think not.

[Gene]

Originally Posted by Kosm1o

At this point in the GM st tire discussion and other st tire discussions , does a speed rating have any believable relevance? I think not.

Yeh, if the tread comes off at 65 or a 106, what's the difference?

Gene

[tvanwave]

Originally Posted by azflycaster

Maybe that was KPH.
65 MPH = 104.6 KPH which is very close.

I recant - I cannot find the website the info came from, so I admit my mistake. Glad to be corrected though!!

[Beginner]

A couple of years ago I posted extensively on the Tires ...Tires...Tires blog and was hammered. I actually talked with the Engineer responsible for tire testing who was employed by the National Highway Transportation Safety Administration. His advice was to obtain a tire with highest speed rating because THE SPEED RATING WAS THE OVERALL ACID TEST OF HOW MUCH A TIRE COULD WITHSTAND BEFORE THE RUBBER COMPOUNDS LOST THEIR INTEGRITY WHICH ALLOWED THE BELTS TO SLIP AND THE TIRE TO FAIL. Simply put, if a tire carries a speed rating of 95 mph, then it can run (when properly inflated according to inflation/weight charts) all day long at 65 or even 70 or what ever speed you are brave enough (or stupid enough) to run at and stay together.
How much sence does it make to run a tire rated at 65 mph at 70 mph. The heat comes from the flexing of the sidewall and the contact with the hot road. Again, we have chosen to purchase the most durable recreation vehicles on the market, why chance damaging them with inadequate tires. The choice is ours, either slow down (to say 55 mph) or buy better tires. The yard stick of better tires is the speed rating.
Beginner

[slowmover]

The same tire [LT] run on a pickup, or run on a trailer, is subject to different ratings by the manufacturer. Things are both a bit simpler and a touch more complicated than they appear.

There's a new thread on WOODALL's involving LT vs ST and has two tire engineers onboard making differentiations and clarifications; as linked in this post on AIR. Upsizing and watching ratings are "good", just how to determine what LT tire is workable now has some numbers attached to it.

.

[Phil&Sher]

Originally Posted by REDNAX

The same tire [LT] run on a pickup, or run on a trailer, is subject to different ratings by the manufacturer......

Hard to understand why, although I'm sure you're right about the different use ratings manufacturers might assign to the same tire. Common sense would make me think that the tire doesn't know what sort of vehicle it's mounted on. The tire just "knows" what conditions it's experiencing: speed, load, inflation pressure, and temperature.

Presuming proper inflation, 55mph on a cloudy, cool day at half rated load should beat 75mph on I-10 in August at max load, no matter what kind of vehicle it's mounted on.

For now, I'm running my Marathons at 65psi, half-max load in the trailer, 55-60mph, with tire pressure/temp monitoring, and hoping for the best.

[slowmover]

The tire just "knows" what conditions it's experiencing

Why it is worth reading the thread. The ratings have to do with the beatings the tire suffers. The ratings may not be perfect (more about wording, perhaps), but an understanding of how they are interpreted (supplied in thread) gives one better guidelines that just "go bigger and heavier" as inflation pressure lower than sidewall maximum is contraindicated. One needs to come closer -- and one can -- is the point.

12-15% load reserve plus max tire pressure is ideal (where the wheel is properly rated and is of correct rim width).

That's it in a nutshell.

But how to cross-reference LT against ST tires is where the devil is in the details. It is not a direct correlation due to use.

.

.

[Bill M.]

For me, the discussion of LT versus ST tires is not really about ratings. ST tires would be great if each tire actually meets the ratings that they are given. But apparantly a much larger percentage of ST tires fail. I have several friends who have had GYM's fail while they were running TPI system and reading 65 psi when it went, and tires were 1 to 3 years old. My choice to go to LT tires is made knowing that they are not the best tire on paper and in spec ratings for the job. But in believing that they are better made and have a lower failure rate than the ST tires. Multiple axles on trailers can cause overloading issues on trailer tires that cars and trucks do not have. My understanding is that the ST tires are rated to allow for this, so I use a large safety factor for the LT tires. But if the ST tires are defective that seems to trump ratings. The tire engineer I know worked for GY, in China for a while, and he runs GY LT tires on his trailer.

[slowmover]

Why you should read the linked thread to the discussion. What fails, why, [probabilities] and how to spec a set of better tires is what it is about. We don't have shoot in the dark in upsizing and transferring ratings from ST to LT.

[rodsterinfl]

Greetings

I am somewhat new here and have asked a lot of questions but now I have a comment on this thread about tires. I spent about a week heavily investigating this issue due to the need for replacement of my just acquired AS. I read many posts here and talked to Good Year cust service, Michelin and also Towmax (conglomerate). I discovered that unless you are willing to buy wheels and tires anew, it is best to stay with ST tires. Here is why. The ST tires have two cords on the sidewall; however they are larger diameter cords for handling weight. The 8 versus 10 ply issue is a weight capacity consideration BUT the wheels have to be able to handle the extra pressure of the 10 ply which is 20-30 lbs more. The tires that were on my 2006 Safari 25 were manufactured on the 41st week of 2004!! They were two years old about the time of original sale. The aluminum wheels that come with AS from 2006 (maybe even earlier) through current are designed for about 60 lbs of psi between load and pressure as per AS tech service. When they removed my OEM tires GY Marathons, they were stamped 6 ply. I did a double take. I ended up with Towmax 8 ply. I found them rated highly overall in several discussions. They are also being used by different companies now as OEM tires.While the LT tire is excellent. It is not designed for side forces that a trailer gets pivoting, etc. That is what I was told.