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 > DOT Endurance Test for ST Tires NOT same for LT Tires

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JIMNLIN

Oklahoma

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Posted: 03/01/21 08:05am Link  |  Print  |  Notify Moderator

ST vs LT and P tire testing per the 571 FMVSS on this web is old old news. Its already been cussed/discussed to the hilt some years ('00s early teens) back so nothing new as its still the same testing procedures per 571 specs.

Way back in '09 a member seniorGNC posted this from 49 CFR 571 tires testing requirement in 5 areas for LT vs ST tire testing.

seniorGNC good read presentation


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Grit dog

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Posted: 03/01/21 09:13am Link  |  Print  |  Notify Moderator

ktmrfs wrote:



what I can say is I've put almost 100K miles on two trailers, my neighbor has put close to 300K miles on two trailers he has for going to races etc. SIL folks have put 50K + miles on trailers.

All with ST tires.

Total number of tire blowouts or catastrophic failures zip, nada, zero. Between the 3 of us we have caught two nail punctures with our TPMS that likely avoided a blowout.

All three of us have run Maxxis and now goodyear endurance tires.


You, I and many others, I'm sure.
Aside from a rash of Goodyear Marathin scalpings in the early-mid 2000s, my experience is the same.


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Timmo!

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Posted: 03/01/21 10:07am Link  |  Print  |  Notify Moderator

Grit dog wrote:

This was Timmos argument to begin with. He’s stuck on LT tires for smaller trailers 14-15” rims that LT tires are unavailable or all but unavailable. And of the very limited choices, they are rated much lower weight than comparable ST tires.

So bottom line, doesn’t matter what the test methods are, if you can’t buy the tire you want.


Grit, if you read my posts in that thread, I "second the emotion" and shared my LT experiences. You were the one trying to debate LT vs ST tires on 14 and 15" rims.

From SeniorGNC's post--

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.

Cummins12V98

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Posted: 03/01/21 11:03am Link  |  Print  |  Notify Moderator

" people don't ride in trailers."

It is very legal to ride in a RV in many States. My wife rode in two of our RV's as her back was killing her.


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Sjm9911

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Posted: 03/01/21 11:33am Link  |  Print  |  Notify Moderator

I would say that the manafatures of the tires run there own tests and pass that info along with the results to get the ratings. Otherwise how would they come up with them? I dont think they guess. This is just the DOT testing and most likely does not represent the actual testing the tires go through by the manafatures when they are concived.


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JIMNLIN

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Posted: 03/01/21 07:10pm Link  |  Print  |  Notify Moderator

ktmrfs wrote:

I only wish there were a selection of LRD or LRE LT tires in 15" to choose from. AFAIK there is only 1 I am aware of, a 15" for sprinter vans.

LRC not an issue in 15"LT, but LRD or E another story. Now if you already have 16" rims, much easier task.

Yeah years back we had handfuls of 14"/15" LT in C/D and some E tires for 1/2 ton size vehicles. Sometime in the '80s 1/2 ton size vehicles started going away with 15" wheel sizes (bigger brakes).

Looking at a RMA info letter on their web 2-3 years back says in a few more years even 16" LT and P tires will follow 14"/15" into history.

Lets all hope the ST tire industry can keep upgrading their C/D/E tire quality.

Timmo mentioned his Goodyear Wrangler on his trailer which is a excellent upgrade but he didn't say what size....just the brand/line name.
Goodyear Wrangler HT comes in LT235/75-15 C load range at 1980 lbs. Several other domestic tire makers did have that size/load range.
Goodyear did have a LT215/85-15 load D at 2095 lbs capacity in the Wrangler HT. Both are a good choice if the capacity works for the axle capacity.

Maxxis in a UE-168 is their commercial LT tire and shows 14" and 15" LT tires sizes in D and E. Check them out.
My Maxxis dealer turned into a Cooper tire dealer so I haven't kept up on Maxxis offerings.

* This post was edited 03/01/21 07:33pm by JIMNLIN *

ktmrfs

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Posted: 03/01/21 08:17pm Link  |  Print  |  Notify Moderator

Those could be a good option for some.

2000 capacity is VERY marginal for my trailer, The Maxxis in LRe might work will need to check them out. I need something in the 2500lb capacity to have a reasonable margin.

* This post was edited 03/02/21 07:12am by an administrator/moderator *


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CapriRacer

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Posted: 03/02/21 07:28am Link  |  Print  |  Notify Moderator

Sjm9911 wrote:

I would say that the manufactures of the tires run there own tests and pass that info along with the results to get the ratings. Otherwise how would they come up with them? I don't think they guess. This is just the DOT testing and most likely does not represent the actual testing the tires go through by the manufacturers when they are conceived.


Allow me to confirm that tire manufacturers do their own testing, but they also do their own rating. DOT does only verification/ spot check testing. If they (DOT) find no issues, no one knows about the tests. If they (DOT) find an issue, they contact the tire manufacturer for clarification.

And just to be clear: Since we are talking about ST and LT tires, the load table is set by the tire standardizing organization - The Tire and Rim Association - and the tires are tested against that standard.

But for speed rating, there is an ATSM (SAE) test - again, conducted by the tire manufacturers for compliance to their published rating which DOT might test for compliance.

And just an FYI, for ST tires, the speed limitation for unrated tires is 65 mph, but there is no published speed limitation for unrated LT tires. Yes, this is a bit of a conundrum.


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mkirsch

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Posted: 03/02/21 08:02am Link  |  Print  |  Notify Moderator

14" and 15" tires are getting hard to find period unless you want some wide low profile thing for your pretend road rally kazoo box.

Back in the day, though, LRC was more than adequate for your typical 1/2 ton pickup that would come with LT rated tires on 15" rims.

Nowadays its getting so you need minimum 16" rims if you want to go with LT tires, and even 17" or 18".


Putting 10-ply tires on half ton trucks since aught-four.

Timmo!

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Posted: 03/02/21 08:24am Link  |  Print  |  Notify Moderator

Jim, I went with Wrangler HT215/75R15--and those tires provided me with nearly 1000 pounds of load capacity (over Marathons).

From the other thread---

Timmo! wrote:

Grit dog wrote:

Timmo! wrote:

I second the emotion---Goodyear Wrangler LT tires


This is not sound advice unless the OP's trailer has 16" or larger wheels, which it most likely doesn't, since it's a TT.
Available ST tires far exceed the capacity of 14" and 15" "LT" tires.


Whoooa Nelly...."not sound advice"? "far exceed capacity"? Let's not exaggerate. A tire that has 2.6% greater load capacity--isn't much of an increase in load capacity (period).

Granted I replaced GY Marathon ST205/75R15 (load range C for 1870 lbs) with GY Wrangler HT215/75R15 (load range D for 2095 lbs), providing me a tire with 225 lb greater load capacity. Now my friend, increasing a tire load capacity of 225 pounds (10.6%) is rather significant

About 4 years ago, ST Marathons were replaced with ST Endurance. So, let's compare those (even though Marathons are still being sold), GY Endurance ST205/75R15 has a load range D for 2150 lbs. I agree the Endurance tire has a greater load capacity of a mere 55 lbs than HT Wrangler, but that is only a 2.6% greater load capacity. Not very much and certainly does NOT "far exceed capacity".

The Endurance has a shallow tire tread depth of 8/32" (0.25"), while the Wrangler has a deeper tire tread of 14/32 (0.4375"), has a wider width and larger diameter, and higher speed rating.

At the time of my tire purchase, the HT Wranglers were only $5 more, and well worth the extra rubber.

Gotta look at the facts.


On edit--corrected math. 2095 - 1870 = 225 lbs, not 255 lbs. My bad.

* This post was edited 03/02/21 09:16am by Timmo! *

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