Tire pressure for Goodyear endurance

[jadatis]

A little correction to my former post.
Read back the copy of the official european formula. It gives " reference load-capacity acording to load index" , and " reference inflation pressure" , but the reference-speed , I filled in myself.

But wait 10 years, and TT makers will provide the new made TT's with Endurance tires, with yust enaugh maxload to cover the GAWR +10%, and then the tirefailure- affaire will happen again, though a bit less percentage , because of the prescribed 10% extra .

[Bob662]

Originally Posted by Tireman9

Airplanes are riveted together but I don't hear about "poped" rivets in that application.

Capri and I are on record of suggesting at least 15% margin. The Interply Shear numbers would suggest that TT need to have a reserve closer to 25%...

If tire companies could all simply improve their ST tires almost overnight, why don't they use the same "magic" tire construction to increase the load rating of their LT type tires?

Anyone?

There are many experimental aircraft that use "pop" rivers and at least one certificated airplane manufacturer uses them -- the Maule series.

The inflation pressures suggested by Andy Thomson do seem to offer those reserves, albeit at pressures well below the maximums molded into sidewalls.

I suspect (1) the stronger sidewalls of the ST tires produce a more harsh ride that the LT tire users wouldn't accept and (2) the LT tires are strong enough.

[Tireman9]

Originally Posted by ROBERT CROSS

^
?

Could it be that the GYE's are constructed better than the GYM's, as in heavier with a much more substantial sidewall>I noticed the heavier weight as soon as they were delivered.🤔

Bob
🇺🇸

While I haven't done a full discretion of GYE I have seen a section. The one obvious difference was the addition of a Nylon Cap over the top steel belt. This will usually improve High-Speed performance and can delay the rate of growth of belt separations. While the lower sidewall was also a bit thicker this increase in lower sidewall can also improve high performance of radial tires.

In general radial tires do not fail because of sidewall "weakness" as long as you keep the air pressure up to where it is supposed to be. Yes a lot of people think that since they can see sidewall flex that must be a weak spot Also many who suffer "blowout" think it was a failure of the sidewall design when in reality the failure was a "Sidewall Flex failure" where after a loss of air the sidewall flexes too much and too fast and the Polyester in the sidewall can actually melt.
I have the pictures that show this on my blog where an Airstream suffered a "Blowout" but the physical evidence showed it was a flex failure where 50% or more air was lost.

[Tireman9]

Originally Posted by Bob662

There are many experimental aircraft that use "pop" rivers and at least one certificated airplane manufacturer uses them -- the Maule series.

The inflation pressures suggested by Andy Thomson do seem to offer those reserves, albeit at pressures well below the maximums molded into sidewalls.

I suspect (1) the stronger sidewalls of the ST tires produce a more harsh ride that the LT tire users wouldn't accept and (2) the LT tires are strong enough.

Didn't mean to imply that "pop-rivets" were not used in aircraft. I was trying to use the term "popped" that it seems many are using to say the rivet had failed and popped out of the hole it was in.


Sorry for the confusion.

[gypsydad]

Originally Posted by Tireman9

Didn't mean to imply that "pop-rivets" were not used in aircraft. I was trying to use the term "popped" that it seems many are using to say the rivet had failed and popped out of the hole it was in.


Sorry for the confusion.

FYI- I worked on several types of jet and propeller driven aircraft while serving in the Navy as an aviation structural mechanic. I saw/replaced many "popped rivets"; not unusual, especially on fighter aircraft. Replacment just like the AS....drill out (if needed) and insert new pop-rivet...good as new!

[Rich W]

Originally Posted by Tireman9

I have the pictures that show this on my blog where an Airstream suffered a "Blowout" but the physical evidence showed it was a flex failure where 50% or more air was lost.

How about this one? It was a GYM on my boat trailer. Damaged the fender and destroyed the wheel because it was bouncing on the highway without any tread, which was wrapped around the caliper, rotor and axle.

[gypsydad]

Originally Posted by ROBERT CROSS

^
?

Could it be that the GYE's are constructed better than the GYM's, as in heavier with a much more substantial sidewall>I noticed the heavier weight as soon as they were delivered.🤔

Bob
🇺🇸

Here is another "expert's" comments about the Endurance after running the Marthons on his TT prior. (he noted the Marathons that "used to be" made in America were working fine, before GY moved manufacture over to China:

"The Endurance is a much more stout tire in comparison to the Marathon, as its load range are only D and E to handle heavier loads. Some of the features of the Endurance include:
◾An optimized tread depth and decoupling groove, which help it remain cool while towing heavy loads;
◾Rugged fabric-steel construction, which offers improved durability and carrying capacity while remaining compatible with tire pressure monitoring systems and typical tire inflation stations;
◾A specialized inner liner, which minimizes air loss in trailer applications; and
◾A scuff guard, which helps protect sidewalls."

Not sure if Tireman has any more specs on the difference in construction to share, but these seem to be preforming well...I now have 18K miles on mine since last summer and they are preforming well at 55PSI cold...happy camper!

[jadatis]

Questions to above post.

3 of 4 of these extra' are also done on LT tires.
And the special profile dept , I read before of old ST to be lesser profile dept, so it has a bit better cooling down , so not that new and special.

Inner liner to prefent pressure loss, every cartire has, so what can make it special for the endurance.

In Europe , for the smaller motorhomes, there is a special camper tire , the CP ( Camping Pneu, french) . Also for that special desighn is writen, with rubber between the ply's , and extra strong sidewalls . I also daubt the alledged antvantages of that tire. If you would take it apart and compare it with a normal C( LT) tire, the differences could be verry small.

That CP is allowed higher pressure then reference, a D load / 8 pr AT 65 or 69 psi then has only written 80 psi on sidewall. And to my conclusions only to cover the general overloading on rear axle, most european motorhomes have.
Though officially they dont support the higher then maxloadcapacity, belonging to the 80 psi.

The ST is to my conclusions , also a tire made to be allowed higher maxload for same tirespecifications in LT, and is not that different in construction then a LT tire. Differences only a downgrade in strength an durabilyty, because for the lower speed this is allowed, and TT makers can put smaller and cheaper tires on TT.

[ROBERT CROSS]

Originally Posted by jadatis

Questions to above post.

3 of 4 of these extra' are also done on LT tires.
And the special profile dept , I read before of old ST to be lesser profile dept, so it has a bit better cooling down , so not that new and special.

Inner liner to prefent pressure loss, every cartire has, so what can make it special for the endurance.

In Europe , for the smaller motorhomes, there is a special camper tire , the CP ( Camping Pneu, french) . Also for that special desighn is writen, with rubber between the ply's , and extra strong sidewalls . I also daubt the alledged antvantages of that tire. If you would take it apart and compare it with a normal C( LT) tire, the differences could be verry small.

That CP is allowed higher pressure then reference, a D load / 8 pr AT 65 or 69 psi then has only written 80 psi on sidewall. And to my conclusions only to cover the general overloading on rear axle, most european motorhomes have.
Though officially they dont support the higher then maxloadcapacity, belonging to the 80 psi.

The ST is to my conclusions , also a tire made to be allowed higher maxload for same tirespecifications in LT, and is not that different in construction then a LT tire. Differences only a downgrade in strength an durabilyty, because for the lower speed this is allowed, and TT makers can put smaller and cheaper tires on TT.

Not all conclusions end up as FACTS.😂

Bob
🇺🇸

[CapriRacer]

I'm going to add my 2 cents worth here on the construction of ST vs LT tires. Just so everyone knows where I am coming from, I was a tire engineer for a major tire manufacturer for over 40 years. I designed them, chased down manufacturing issues, analyzed failed tires, interacted with Ford on the qualification process, analyzed return data, and advised dealers and consumers on their care and use.

I am of the opinion that the construction difference between ST tires and LT tires is - well ….. - there isn't any. Why opinion? Because I didn't actually design any. I am basing my opinion on HOW other types of tires are designed, and in particular how LT tires are designed.

So why the perceived performance difference?

1) An ST tire carries 20% more load than the same "size" LT tire - AND - it carries a 65 mph speed limitation that the LT tires don't (unless otherwise indicated.) If you "back out" the speed limitation, you get about the same loads as an non-speed-rated LT tire. (I leave the exercise for those who are more convinced if they do it themselves!)

Plus, ST tires typically, in service, carry a larger percent of their rated load than their LT tires cousins.

2) ST tires are not mainstream, so they tend to lag behind LT tires in technology - that is, they don't benefit from the latest innovations, particularly if that requires upgraded building equipment. Traditionally, they've been using old molds and building equipment that would otherwise have been scrapped. Nothing wrong with that if it doesn't harm performance, but it took a bit too long for the performance to be noticed.

3) Trailer manufacturers didn't do a good job of selecting the load carrying capacity of the tires they specified. (No, the tire manufacturer doesn't select the tire, the vehicle manufacturer does! - and in the case of trailer manufacturers, there are so many and they are so small and they buy though wholesalers, that it takes a while to get everyone on board about how to select the right tire for the job.)

So what about today? From what I've seen, there has been a push from the tire manufacturers - albeit a bit delayed - to bring the construction up to date - particularly cap plies. The Goodyear Endurance is the poster child here. The tire line was introduced in the fall of 2016 and there have been no reported durability failures to date. My experience says that the third summer is when the failure rate peaks, and the earliest production is in the final months of that 3rd summer.

So what took so long? First, prior to the huge Ford/Firestone situation back in August of 2000, all steel belted radial tires had those same issues. When that hit, the tire manufacturers made a series of changes to the passenger car tire lines. It took a while to research what was needed and implement that. (I could go back to the 1970's when steel belted radial tires were first introduced and point to those same issues, but at a higher rate - remember the Firestone 500?)

Once the passenger car tire lines were upgraded and the improvements verified, the manufacturers started to address the next largest production volume tires - LT's. Those took a bit more than just implementing what was learned in PC tires - so it took a couple of rounds to get it right. (Just for reference, it takes 3 years to be sure if a tire modification works - and if it doesn't, it takes another 3 years for the next one.)

Where the big hiccup for ST tires existed was that only the major tire manufacturers had good feedback systems to monitor field performance - and there was only one who made ST tires - AND equipment upgrades had to be designed, manufactured and installed.

Now I am going to address the differences currently between ST tires and LT tires:

1) Tread depth: ST tires don't wear very fast. They don't do much more than follow, so there isn't a need to provide a lot of rubber depth.

2) Tread width:. Since trailer tires don't need to provide much cornering power, they don't need much width on the road.

Then there are things that can't be readily identified, like the rubber compounds and such details. I see no reason why a particular tire manufacturer couldn't use the same materials for ST tires as for LT tires. I also don't see any reason not to use the latest construction details - such as where to put extra rubber thickness (and the like).

So there you have it. My take on ST tires and where things currently stand.

[GCinSC2]

CapriRacer,

Appreciate the info, thanks.

And I just spent some time on your page, bookmarked for additional reading.

Gary

[jadatis]

Also my thanks to CapriRacer, a lot is in line whit what I concluded in time, only by administrative research.

About the 20 % higher maxload.
Maxload is calculated to give no overheating of any part of tire when driving the speed for wich it is calculated.
For that you have to determine the deflection of tire when warm at that speed.
Only warm is not that reliable to measure, so cold pressure is used because pretty reliable .

So I now go for simplicity reasons from cold deflection. And a rough calc.

A ST calculated for 65mph in maxload, a LT for 99mph .
Gives 99/ 65 as much cicles a second/ minut/ hour, will use second.
ST have 2/3 of speed so can have 3/2 of deflection. This gives root 3/2 of surface on the ground is 1,22 times as much. With same pressure , going from weigt is surface times pressure, gives 22% more maxload for that speed.
CR estimated 20% , and with a little rounding down , because rolingcircumference is smaller at more deflection, so more cicles a second at same speed, and mayby heatproduction is not lineair with deflection, my rough calc comes down to it.

[gypsydad]

Originally Posted by jadatis

Also my thanks to CapriRacer, a lot is in line whit what I concluded in time, only by administrative research.

About the 20 % higher maxload.
Maxload is calculated to give no overheating of any part of tire when driving the speed for wich it is calculated.
For that you have to determine the deflection of tire when warm at that speed.
Only warm is not that reliable to measure, so cold pressure is used because pretty reliable .

So I now go for simplicity reasons from cold deflection. And a rough calc.

A ST calculated for 65mph in maxload, a LT for 99mph .
Gives 99/ 65 as much cicles a second/ minut/ hour, will use second.
ST have 2/3 of speed so can have 3/2 of deflection. This gives root 3/2 of surface on the ground is 1,22 times as much. With same pressure , going from weigt is surface times pressure, gives 22% more maxload for that speed.
CR estimated 20% , and with a little rounding down , because rolingcircumference is smaller at more deflection, so more cicles a second at same speed, and mayby heatproduction is not lineair with deflection, my rough calc comes down to it.

Goodyear Endurance Max Speed rating as I see on their spec, is Specs 87mph. , and is considered a 10ply tire. appreciate all the good advise and knowledge on this thread. I still will follow the recommended PSI/weight chart from GY and run at 55 PSI cold...YMMV!

Goodyear Tires and Wheels - 724857519

Radial special trailer tire with automotive-grade tread has a 10-ply rating and a 2,830 max load at 80 psi. Durawall technology and scuff guard protects sidewall from damage. Decoupling grooves help reduce irregular tread wear. Fits 15" wheels.


Features:
•Radial ply tire is great for highway use
•Constructed with double steel belts and triple polyester plies for a long life
•Nylon tread-firming belt overlays help prevent tread separation
•Tread wear indicator (TWI) makes it easy to see tread depth
•Automotive-grade tread channels water away from the tire to improve traction during wet, snowy, or icy conditions
•Durawall technology reinforces the sidewall with a rubber compound to prevent cuts and punctures◦Raised scuff guard on the sidewall provides additional protection against curb damage

•Decoupling grooves minimize irregular tread wear and keeps tire cool while you're towing
•Inner liner with halobutyl rubber construction reduces air loss
•Special trailer (ST) tire has sturdy sidewalls so that it can handle heavy loads◦Created specifically for trailers and not intended for use on other vehicles

•Meets DOT specifications
•Made in the USA

•Capacity:◦Load range: E
◦Ply rating: 10
◦Maximum load: 2,830 lbs at 80 psi

•Tread depth: 8/32"
•Maximum speed: 87 mph (speed rating N)
•Limited warranty with free tire replacement