Forum Discussion

Bruce_H_'s avatar
Bruce_H_
Explorer
Dec 28, 2014

Maxxis Ue-168

I've been interested in the Maxxis UE-168 as a LT replacement for the 14" ST tires that came with my trailer. The original tires were Trail America ST 205/75R14. After one year I upgraded to the Maxxis M8008 ST 215/75R14. Come next Spring the tires are reaching the three-years-from-manufacture date, and it will be time to replace (being I am very conservative about tire risk).

I wrote to Maxxis USA and inquired about the use of their UE-168 tire for my intended usage. They replied that it was inappropriate to use any LT tire, including their UE-168, for use on a trailer.

However, in bouncing around on the internet, I discovered that Maxxis in the United Kingdom actually recommends the UE-168 for trailer use. Link: http://www.maxxis.co.uk/tyres/trailer

Should I ignore Maxxis USA and go ahead with the UE-168?

Bruce
  • Huntindog's avatar
    Huntindog
    Explorer
    Dec 29, 2014
    coolbreeze01 wrote:
    "BTW... Did you notice the low inflation test that the LT has to pass? The ST doesn't have to do it at all. That is a very realistic possibility in the real world. A tire with a slow leak, running low on air. Even the ST proponents will tell you that is death to an ST tire. They are right, as there is no standard for it to meet. OTOH, the LT tire will give you a fighting chance of avoiding a catastrophic blowout under that situation, because it is REQUIRED to pass such a test."

    If I could buy a 225 75 15" LR E LT tire I would have them on my trailer.

    By the way, notice the blown truck tires on any highway. I've been told if there is steel showing, it was a new tire, not a retread. Basic cause, heat buildup due to low air.
    You can probably make the jump to 16s. I did it on my last two TTs.
    Had to buy rims and 6 lug drums on the first one. The second TT already had 6 lug rims, so I just swapped the 16s over to it.
  • coolbreeze01's avatar
    coolbreeze01
    Explorer
    Dec 29, 2014
    "BTW... Did you notice the low inflation test that the LT has to pass? The ST doesn't have to do it at all. That is a very realistic possibility in the real world. A tire with a slow leak, running low on air. Even the ST proponents will tell you that is death to an ST tire. They are right, as there is no standard for it to meet. OTOH, the LT tire will give you a fighting chance of avoiding a catastrophic blowout under that situation, because it is REQUIRED to pass such a test."

    If I could buy a 225 75 15" LR E LT tire I would have them on my trailer.

    By the way, notice the blown truck tires on any highway. I've been told if there is steel showing, it was a new tire, not a retread. Basic cause, heat buildup due to low air.
  • Huntindog's avatar
    Huntindog
    Explorer
    Dec 29, 2014
    coolbreeze01 wrote:
    "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."

    When I plan to run 100 mph, I'll definitely have LT tires or better. Until then, I'll just run the best 15" tires I can buy.
    You probably don't tow at 85 MPH either... But the ST tire is tested at that speed.... Since you don't tow that fast, perhaps a different tire should be used, that is tested to your towing speed... something off of a wheelbarrow maybe.:B

    Obviously a joke. The test standards are not mean't to replicate your towing. But to push the tires hard in a short time span. The tougher the test, the better it will do long term under actual towing.

    BTW... Did you notice the low inflation test that the LT has to pass? The ST doesn't have to do it at all. That is a very realistic possibility in the real world. A tire with a slow leak, running low on air. Even the ST proponents will tell you that is death to an ST tire. They are right, as there is no standard for it to meet. OTOH, the LT tire will give you a fighting chance of avoiding a catastrophic blowout under that situation, because it is REQUIRED to pass such a test.

    Also note, that all of the marketed benefits of ST tires (shallow tread, more UV protectant, stronger sidewalls, lower traction tread, etc.) are not tested at all. So it basically allows the marketing dept. to claim whatever they want to make the tire sell. Nobody is testing these things on either tire type.
  • MM49's avatar
    MM49
    Explorer
    Dec 29, 2014
    Last Fall I garbage picked a couple of 1980's 20" dump truck tires on wheels. I wanted the wheels to make camp fire rings.

    The tires were before the federal mandated labeling on the side walls. The tires were only marked "load range E". The rear tire was marked load range E for the D position. Both the front tire and rear tire were Kelly Springfield nylon tires.

    I tried to dismount the tires, but I couldn't break the beads, so I decided to cut the tires off the wheels with a razor knife. After the tires were off I used an abrasive wheel to cut the bead to remove it.

    The front steering axle tire was completely different design than the rear tire. Both tires were the same weight rating, E. Both tires have the same number of cords. The rear D tire had larger cords with thicker rubber between them. The rear D tire was almost twice as thick as the front tire.

    I believe that this D position tire is the same practice as today's ST tires. I think that the thicker rubber is to dissipate heat between the nylon cords. The front tire was the standard LT construction. This heavy duty construction has been an industry standard for more the 35 years. There has to be a reason why they are invested in a more costly design? The heavy duty design is stronger, but more susceptible to generating heat when run at low pressure or over loaded. The thicker rubber between the cords creates more heat when flexed at low pressure or overloaded.

    The reason the tire had a D position rating is because it was designed to run as a dual rear wheel. Dual wheel tires are derated 10% because the outer wheel applies force on the inner wheel due to the camber of the road. This is why they need a stronger tire that can flex in the D position. I believe the same theory applies to ST tires on RV's we need a strong tire that can flex.

    MM49
  • coolbreeze01's avatar
    coolbreeze01
    Explorer
    Dec 28, 2014
    "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."

    When I plan to run 100 mph, I'll definitely have LT tires or better. Until then, I'll just run the best 15" tires I can buy.
  • Huntindog's avatar
    Huntindog
    Explorer
    Dec 28, 2014
    PawPaw_n_Gram wrote:
    jfkmk wrote:
    I wonder if it is a U.S. Thing. That is, I wonder if any other tire company in the U.S. recommends a LT tire for use on a trailer. What would make the Maxxis lt tires any different than any other manufacturers?


    LT tires in the US are not tested and certified for trailer use. If the government says they are not certified for trailer use, the company shouldn't recommend them.

    However, we all know that a lot of people put LT tires on their trailers, and feel that they are a better choice than ST tires.
    Or put another way, ST tires are not certified for passenger car use.... In reality the testing standards don't involve trailers at all. I have actually read the testing standards. As usual, the govt. can make a ham sandwich needlessly complicated. The standards are difficult to read, as they keep referring to different sections that all must be read, to get it.

    But, the good news is that you don't have to.
    A fellow member, Senior GNC did all of that and wrote a summary , complete with all of the references to make it easy to read. It is very good and accurate, and will open your eyes.
    Here it is:

    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=090163348008f295
    LT tire standard may be found at FMCSA Part 571, subsection 139.
    http://www.fmcsa.dot.gov/rules-regulations/administration/fmcsr/fmcsrruletext.aspx?chunkkey=090163348008f2a9
    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=090163348008f29d

    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 *


    Link to the thread:LT vs ST testing standards
  • jerem0621's avatar
    jerem0621
    Explorer II
    Dec 28, 2014
    I'd replace them with the Maxxis LT's and forget about tire problems.

    Thanks!

    Jeremiah
  • Bruce_H_'s avatar
    Bruce_H_
    Explorer
    Dec 28, 2014
    downtheroad wrote:
    Replacing at 3 years certainly is being VERY (overly) conservative.
    What didn't you like about your Maxxis 8008's?
    Did they fail? Did they give you bad service or trouble?
    Just wondering.


    The tires have been just fine. However, they do not have the nylon cap; that's only available on the 15" and 16" M8008 tires. Also, the tires have only 13% reserve capacity, and would like to get that up to about 30%, similar to what one would find on typical automotive applications.

    Having once had a tread separation that demolished the wheel well and severely damaged the surrounding cabinet on a Chalet trailer, with one-year-old tires that had never been abused, I am not very trusting of ST tires.

    Bruce
  • wanderingbob's avatar
    wanderingbob
    Explorer II
    Dec 28, 2014
    In the U.S. we sue each other at the drop of a hat so many manufacturers are very conservative . I would not shy away from LT tires if that was what that I wanted !My next 14s will be Kumhos.

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