Tire Advice

[uconn_jack]

Hi,

I recently had a blowout on my 2009 Skyline Layton 2970 TT (8,800 GVWR). Bought it used late last year, great shape, with Goodyears (including spare) on it that also looked in good shape and that I understand were about 3 yrs old. Tread-wise they have at least another year to them, and since I am on a bit of a budget, I could just put the current spare into use and get a new spare. However, even being Goodyears, with the blowout I'm not sure I trust the rest and would rather buy 4 new.

I know how most feel about "china-bombs", but I am on a budget so can't go with the Maxxis or Sailuns everyone raves about. Plus I'm not convinced its as big of a problem as its made out to be (my old TT had Greenballs and then HiRuns, never had a blowout until the Goodyears). So anyway, I have narrowed it down to the following tires (ST225/75R15):

Power King Towmax Vanguard - Load Index 117, Load Range E, Speed N
Trailer King RST - Load Index 117, Load Range E, Speed M
Gladiator QR25-TS - Load Index 117, Load Range E, Speed N
Carlisle Radial Trail HD - Load Index 113, Load Range D, Speed M

Now I know Carlisle is the only one of these brands that seems to be acceptable by many, and it is only about $10-15 more per tire than the others, but it does have lower load and speed specs than the others. The Carlisle specs are sufficient for my TT weight, but I am wondering if getting more load buffer with the 117/E tires might be better, despite those tires being held in less regard.

Looking forward to opinions! Thanks!

[StirCrazy]

Huntindog wrote:
09/22/09 09:22pm Link | Print | Notify Moderator
This post is an open letter to the RV.net community whom have been following the ongoing tire discussions.

I have been following these discussions, but until lately I have been staying on the sidelines until the topic took a turn to a more factual basis. I have personally experienced multiple failures with my 5th wheel and ST tires, both D and E load range and would like to understand why this appears to happen more often with ST (special trailer) vs. LT (light truck) tires. (Based on this forum it must be considered anecdotal and not conclusive evidence.)

To resolve this matter I have investigated the current Federal Motor Carrier Safety Administration (FMCSA) testing standards that ST and LT tires must meet to be certified to be sold in the United States.

*

this is pretty good, but its missing one thing. the tread on a St tire is designed to allow it to scuff sideways easier, as in when you a sharp 90 degree or more turn when backing into a site. a LT tire will be designed to grip the road more giving you higher values on the g pad, not that were pushing our trucks for 1 plus gee's but you want that grip when off road and such. I wonder if there is any testing procedure for Interply shifting?

[manley]

To heck with the GY Endurance. I just had a failure today, on 3-year old Endurances. Tread separation, with damage to the trailer. Tire never lost pressure. Actually looks like a retread that came off. Tires were properly inflated at 80 PSI. ??

[mosseater]

On our 3rd set of Maxxis and have had zero issues. I'll guess most trailer tires run out of date before tread. When the cracks start appearing on side wall and between tread rows, I buy new. Have gotten 7-8 years out of all Maxxis I've bought at around $120 per.

[Samsonsworld]

I've had good luck with Goodyear and Maxxis.

[Huntindog]

Grit dog wrote:
Well I think there’s one mfg making a 15” LT tire that is marginally up there with the heavy duty STs.
This is like one of those bad reccomendations that just doesn’t go away….

On the TT I first made the jump from STs to LTs I went from 15" rims to 16", There are a ton of great LT tires in the 16" wheel size.

[aftermath]

UconnJack, tires fall into that "pretty important" category. I believe in purchasing from a reputable dealer who will stand behind their tires. I is "important" to go with a good brand, important to get the right size, important to maintain and care for them and really important to watch them carefully. That said, I have had the old Marathons, a set of Maxxis and now am on my second set of Carlisle Radial HD ST tires. These have been the best so far. I also uprated mine to LRE when a D load would have probably covered my weight adequately. I run mine at about 72psi for normal trips but will load them up to 80 when it gets really hot outside.
Some people believe that a tire manufactured overseas is automatically a bad tire. Conversely, they believe that if it was made in the USA then it has to be good. Goodyear manufactured their Marathons here and had trouble with them. They moved manufacturing overseas and still had trouble. They also caved to the "buy American" pressure and brought the Marathon back. None of it seemed to help. They junked the Marathon and went with an improved tire. So.....WHO makes the tire is more important than WHERE it is manufactured. Just my 2 cents.

[JIMNLIN]

time2roll wrote:
Goodyear Marathon or Goodyear Endurance?

What part blew out? Separating tread? Sidewall failure? Any chance of road hazard ran it low on air?

The Endurance came out in 2017. He says the tires may have been 3 years old.

[time2roll]

Goodyear Marathon or Goodyear Endurance?

What part blew out? Separating tread? Sidewall failure? Any chance of road hazard ran it low on air?

[Grit_dog]

Well I think there’s one mfg making a 15” LT tire that is marginally up there with the heavy duty STs.
This is like one of those bad reccomendations that just doesn’t go away….

[Huntindog]

09/22/09 09:22pm Link | Print | Notify Moderator
This post is an open letter to the RV.net community whom have been following the ongoing tire discussions.

I have been following these discussions, but until lately I have been staying on the sidelines until the topic took a turn to a more factual basis. I have personally experienced multiple failures with my 5th wheel and ST tires, both D and E load range and would like to understand why this appears to happen more often with ST (special trailer) vs. LT (light truck) tires. (Based on this forum it must be considered anecdotal and not conclusive evidence.)

To resolve this matter I have investigated the current Federal Motor Carrier Safety Administration (FMCSA) testing standards that ST and LT tires must meet to be certified to be sold in the United States.

First I have some folks that I would like to thank for providing me the desire to delve into this issue:
“Chris” for moving the topic in a more factual direction.
“Tireman9” for helping me find the federal standards.
“FastEagle” for his willingness to challenge group thought and to encourage me to understand the perceived performance discrepancies between these types of tires.
Thanks guys!

For those of you who just wish to get the big picture facts, I have started with a summary section. This hits all the high points and you my quit after reading this. (No need to read all the details if you don’t want to!)

If you wish to understand my research in greater depth (and verify my findings and conclusions), after the summary I have provided the following sections: references, notes, and testing of (1) bead unseating resistance, (2) strength, (3) endurance, and (4) high speed performance.

SUMMARY OF FINDINGS & CONCLUSIONS

I found the testing requirements for both the ST and LT tires at the Federal Motor Carrier Safety Administration (FMCSA) webpage.

The testing for each tire is comprised of (1) bead unseating resistance, (2) strength, (3) endurance, and (4) high speed performance.

The testing for (1) bead unseating resistance and (2) strength were identical for tires representative of moderate to heavy 5th wheels and thus no advantage is given to either tire type.

The testing for (3) endurance was found to be significantly different between the ST and LT tires.

Both the ST and LT are put through the same initial pressure, time and load profile. The total profile lasts 34 hours of continuous run time starting at 85% of rated load and ending at 100% of rated load. To further stress the tires, a load range E tire (nominal 80 psi rating) is tested at a reduced pressure of 60 psi to induce additional load on the tire during testing. (This is reasonable that testing should be conservative.)

But now the endurance testing diverges significantly.

The ST tire is tested at this pressure, time and load profile at 50 mph. After that, the ST test is over.

The LT tire is tested at this pressure, time and load profile at 75 mph. This is a 50% increase over the ST and will induce significant additional load and heating on the tire during testing. After that, the LT test is not complete. Next a “Low Inflation Pressure Performance” test is performed for the LT tire only. The tire pressure is decreased to 46 psi and the tire is immediately run for an additional 2 hours at 75 mph and 100% of rated load.

Thus, the LT tire endurance test is drastically more intense than the ST endurance test.

The testing for (4) high speed performance.

The difference in high speed performance testing between a ST and LT tire is significant. Both tires are tested through a 90 minute speed/time profile.

The ST tire is tested 88% of rated load while the LT tire is tested at 85% of rated load. Thus, the loading is 3% higher based on rated load and this slight advantage goes to the ST tire.

However, the LT tire is tested at significantly higher velocities when compared to a ST tire (99 vs. 85 mph maximum speed). This is a 16% advantage to the LT tire.

Thus, again the overall test for the LT is more rigorous than the ST test.

Conclusion:

It is reasonable to conclude that these test requirements force the tire manufacturer to construct an LT tire more substantially than an ST tire. This is also a reasonable explanation for the same size LT tire is rated at a slightly lower maximum load than a ST tire.

And now, for those of you who need to know all the details, read on!

REFERENCES

The references for my evaluation may be found at the Federal Motor Carrier Safety Administration (FMCSA) webpage:
ST tire standard may be found at FMCSA Part 571, subsection 109.
http://www.fmcsa.dot.gov/rules-regulations/administration/fmcsr/fmcsrruletext.aspx?chunkKey=09016334...
LT tire standard may be found at FMCSA Part 571, subsection 139.
http://www.fmcsa.dot.gov/rules-regulations/administration/fmcsr/fmcsrruletext.aspx?chunkkey=09016334...
Part 571, subsection 139 references Part 571 subsection 119 which can be found at:
http://www.fmcsa.dot.gov/rules-regulations/administration/fmcsr/fmcsrruletext.aspx?chunkKey=09016334...

QUICK NOTES

Each standard for the ST and LT tires has definitions, significant constraints on labeling, etc. that I will not address. There are also tire conditioning (temperature), tire break in, etc. that are the same or similar for ST and LT that I will not address. The details are in the references.

The (3) endurance, and (4) high speed performance tests must not result in tire failure. Tire failure includes visual evidence of tread, sidewall, ply, cord, inner liner, or bead separation, chunking, broken cords, cracking, or open splices, not just a blowout.

TESTING - BEAD UNSEATING RESISTANCE

ST Tire: (reference paragraph S5.2.2)

The tire is mounted horizontally and a vertical load is applied to the tire’s outer sidewall at a rate of 50 mm (2 inches) per minute.

Increase the load until the bead unseats or a specified value is reached.

Repeat the test at least four places equally spaced around the tire circumference.

LT Tire:

Paragraph “S6.6 Tubeless tire bead unseating resistance” references the ST tire procedure noted above.

Conclusion:

The testing for bead unseating resistance is identical for a ST and LT tire.

TESTING - STRENGTH

ST Tire: (reference paragraph S5.3.2.1)

Force a 19 mm (3?4 inch) diameter cylindrical steel plunger with a hemispherical end perpendicularly into the tread rib as near to the centerline as possible, avoiding penetration into the tread groove, at the rate of 50 mm (2 inches) per minute.

Compute the breaking energy for each test point by means of a provided formula.

LT Tire: (reference paragraph S6.5.2)

Each tire shall comply with the requirements of S7.3 of 571.119, which is tires for vehicles weighing 10,000 lb or more. Per S7.3 of 571.119 for our example tire, the testing is the same as the ST tire procedure noted above.

Conclusion:

The testing for strength is identical for a ST and LT tire.

TESTING - ENDURANCE

The following is for a ST or LT tire of less than nominal cross section less than or equal to 295 mm (11.5 inches) which is typical of a 5th wheel application.

ST tire: (reference paragraph S5.4.2)

There are specifications for the contact of the tire mounted on a test axle and steel test wheel after the test that I will not address because they are similar for the ST and LT.

Inflate a load range E to 60 psi. (410 kPa)

Conduct the test at 80 kilometers per hour (km/h)(50 miles per hour) in accordance with the following schedule without pressure adjustment or other interruptions:

The loads for the following periods are the specified percentage of the maximum load rating marked on the tire sidewall:
Time and Percent of rated load
4 hours, 85%
6 hours, 90%
24 hours, 100%

LT Tire: (reference paragraph S6.3.1.2)

“Conduct the test, without interruptions, at the test speed of not less than 120 km/h…” (75 mph)

Inflate a load range E to 60 psi. (410 kPa)

This test uses the same profile as the ST tire.

Immediately following the above sequence perform a Low Inflation Pressure Performance test (reference paragraph S6.4):
This test uses the same tire/wheel as the previous sequence at a reduced pressure.

For a load range E tire the pressure is reduced to 46 psi. (320 kPa)

The same tire/wheel is run an additional 2 hours at the reduced pressure at a speed of 75 mph and 100% of rated load.

Conclusion:

The difference in endurance testing between a ST and LT tire is significant. Both tires are tested through a equivalent loading/time profile. However, the LT tire is tested at this profile at a higher speed (75 vs. 50 mph) and must still endure an additional 2 hour low pressure test without failure. Thus the overall test for the LT is far more rigorous than the ST test.

TESTING - HIGH SPEED PERFORMANCE

ST tire: (reference paragraph S5.5.4)

Load the tire to 88 percent of the tire’s maximum load rating as marked on the tire sidewall. Inflate to 72 psi (500 kPa). Run the test sequentially without interruption at:
75 mph (121 km/h) for 30 minutes
80 mph (129 km/h) for 30 minutes
85 mph (137 km/h) for 30 minutes

LT Tire: (reference paragraph S6.2.1.2.7)

Load the tire to 85 percent of the tire’s maximum load rating as marked on the tire sidewall. Inflate to 72 psi (500 kPa). Run the test sequentially without interruption at:
87 mph (140 km/h) for 30 minutes
93 mph (150 km/h) for 30 minutes
99 mph (160 km/h) for 30 minutes

Conclusion:

The difference in high speed performance testing between a ST and LT tire is significant. Both tires are tested through a speed/time profile. The ST tire is tested 88% of rated load while the LT tire is tested at 85% of rated load. Thus, the loading is 3% higher based on rated load and this slight advantage goes to the ST tire. However, the LT tire is tested at significantly higher velocities (nearly 100 mph!) when compared to a ST tire. This is a 16% advantage to the LT tire. Thus, again the overall test for the LT is more rigorous than the ST test.

* This post was edited 09/23/09 04:30pm by SeniorGNC *

[Huntindog]

uconn_jack wrote:
Hi,

I recently had a blowout on my 2009 Skyline Layton 2970 TT (8,800 GVWR). Bought it used late last year, great shape, with Goodyears (including spare) on it that also looked in good shape and that I understand were about 3 yrs old. Tread-wise they have at least another year to them, and since I am on a bit of a budget, I could just put the current spare into use and get a new spare. However, even being Goodyears, with the blowout I'm not sure I trust the rest and would rather buy 4 new.

I know how most feel about "china-bombs", but I am on a budget so can't go with the Maxxis or Sailuns everyone raves about. Plus I'm not convinced its as big of a problem as its made out to be (my old TT had Greenballs and then HiRuns, never had a blowout until the Goodyears). So anyway, I have narrowed it down to the following tires (ST225/75R15):

Power King Towmax Vanguard - Load Index 117, Load Range E, Speed N
Trailer King RST - Load Index 117, Load Range E, Speed M
Gladiator QR25-TS - Load Index 117, Load Range E, Speed N
Carlisle Radial Trail HD - Load Index 113, Load Range D, Speed M

Now I know Carlisle is the only one of these brands that seems to be acceptable by many, and it is only about $10-15 more per tire than the others, but it does have lower load and speed specs than the others. The Carlisle specs are sufficient for my TT weight, but I am wondering if getting more load buffer with the 117/E tires might be better, despite those tires being held in less regard.

Looking forward to opinions! Thanks!

Do whatever it takes to get quality tires on it. This means LT tires. ST tires are all junk. The gov. testing standards for them are a joke. They have much lower standards because they are not rated for passenger vehicle use.

[mdcamping]

uconn_jack wrote:
Hi,

I recently had a blowout on my 2009 Skyline Layton 2970 TT (8,800 GVWR). Bought it used late last year, great shape, with Goodyears (including spare) on it that also looked in good shape and that I understand were about 3 yrs old. Tread-wise they have at least another year to them, and since I am on a bit of a budget, I could just put the current spare into use and get a new spare. However, even being Goodyears, with the blowout I'm not sure I trust the rest and would rather buy 4 new.

I know how most feel about "china-bombs", but I am on a budget so can't go with the Maxxis or Sailuns everyone raves about. Plus I'm not convinced its as big of a problem as its made out to be (my old TT had Greenballs and then HiRuns, never had a blowout until the Goodyears). So anyway, I have narrowed it down to the following tires (ST225/75R15):

Power King Towmax Vanguard - Load Index 117, Load Range E, Speed N
Trailer King RST - Load Index 117, Load Range E, Speed M
Gladiator QR25-TS - Load Index 117, Load Range E, Speed N
Carlisle Radial Trail HD - Load Index 113, Load Range D, Speed M

Now I know Carlisle is the only one of these brands that seems to be acceptable by many, and it is only about $10-15 more per tire than the others, but it does have lower load and speed specs than the others. The Carlisle specs are sufficient for my TT weight, but I am wondering if getting more load buffer with the 117/E tires might be better, despite those tires being held in less regard.

Looking forward to opinions! Thanks!

Welcome aboard!

I always used the Goodyear Endurance tires.

If you live close to central CT, Bolton Notch RV Storage does good service work on Rvs, maybe give them a call. I don't remember the brand but they also they do offer another cheaper tire that they have had good experience with if you want to save some money.

Good luck
Mike

[pbeverly]

You are seeing comments about the cost of a blowout being far higher than the cost of god tires.

My blowout cost over $4000 and took 9 mmonths to get it 95%v fixed.

[2112]

Grit dog wrote:
If you’re on a budget then you should look at the mfg dates on the tires for free and see if they’re really only 3 years old. And if they are, and haven’t been constantly beat by the sun in the desert or some equally as destructive treatment, then buy one tire to replace the blowout.
And I’d buy an E rated tire because, why not?

I agree with the above except, if you have 3 good GY Endurance replace the 1 tire with the same. The Endurance has a heavy, thick, stiff side wall that doesn't flex as much. A cheaper tire would behave differently.

I rode on Endurances for 6 years. I had to run them at 70psi to keep them from bouncing. I replaced them with cheap Contenders. I can run them at 80psi with no bounce

[JBarca]

Looking over your new tire list and reviewing the Goodyear, here are some comments to consider.

On the Goodyear that had the blowout, I'm assuming you are referring to the Endurance trailer tire? If so, the ST22575R15 tires were in an E load range, with a Load index 117. Correct me if I have stated this wrong.

Here are some questions to ask yourself.

Something caused that tire to have a blowout; why? What is the DOT date code on the tires on the camper now? Assuming you bought all four simultaneously, they should be close. You are after the date of manufacture, not the date you installed them.

What tire pressure do you run those tires at?

Do you make a lot of hard 90 or 180 turns with the camper on a hard surface at your home/storage place every time you come and go to a campout?

Have you weighed the camper, axle by axle, and ideally, each wheel position?

What tire load range did Skyline place on the camper? With an 8,800 GVWR sounds like you already took a jump to E load range from what may have been a D load range by Skyline.

Comments on what may have happened.

There is a term called "interply shear" that happens on tandem axle trailers in turns. In a turn on a tandem or triple axle trailers, the tire tread and tire internals are getting stressed from the high friction between the road and the tire, when the tread does not slip on the road. The tire has to withstand this effect. Look this topic up on the web, it happens and is more aggravated by low air pressure, overloading, lots of hard turns, and tire age, to name a few.

Something caused your tire to blow out; think through what may have happened and why so you can correct it in the future. If you are low on pressure, that is a problem. The only way to lower the risk of interply shear that is practical, is more reserve load capacity per the loaded tire. This reserve capacity is above the stated rating on the tire. Some tire experts (I'm not one of them, but I had to deal with his) suggest 20% extra reserve tire capacity over the heaviest loaded wheel.

If you already jumped to E load range over the factory D load range, you could gain more reserve load capacity, but you will only get the increased reserve capacity from increased air pressure in the E load range tires. Suggest running them at the max cold side wall stated pressure on a trailer.

Was there a series of big potholes on a trip sometime? Potholes at 50 to 60 mph are bad news to a trailer tire, especially if the pressure is not at max. Damage internally can start that then takes a long time to rear its ugly head with a blowout.

There is a common trend on tandem or triple axle trailers when one tire blows out. The tires are at or close to or at full load capacity all the time. When the blowout happens, the other tires on that side go into overload. Now they have taken a hit of internal damage. It is common that those other tires can fail prematurely as time goes on. All of your fears about changing them now are a good concern. You are at increased risk if the damaged tires are not changed.

Having lived through the trailer damage that can occur when the tread flys off, the camper repair cost can outweigh the tire cost. Do you want the risk of simultaneously dealing with camper damage on top of new tire costs?

Not sure if you have a TPM (tire pressure monitor) on the camper; if not, consider adding one in the future.

I also noticed in your list of new tires; the Carlises were not at the 113 load index and not the 117 load index of the others. To give the Carlises a fighting chance, go with the 117 load index.

Try and figure out what caused your blowout and how to prevent it for the next time.

Hope this helps

John