D versus E

[Beginner]

LI Pets:
Your tires are the Duravis M77311II I have to assume. According to Tire Rack those tires if a 245/75R16) carry the specifications of 120/116R E (Speed Rating of R which is 106 MPH. If it’s the 265/75R16 they carry the specifications of 123/120Q (Speed R
ating of Q which is 100 MPH) according to this website:
http://www.tirerack.com/tires/Spec.jsp?make=Bridgestone&model=Duravis+M773II&tir ePageLocQty=
ROBERT SUNRUS, your tires are Speed Rated at 110T or a Speed Rating of 118 MPH according to the web site noted above.
Why are you two wasting your money on those tires or do both of you drive the unhooked tow vehicles a 100 MPH?
There are tires available with a Speed Rating of K ( 68 MPH) and L (75 MPH) which according to your arguments would serve you just fine and are probably cheaper.
As per LI Pets request I will endeavor to find the information from a engineer or engineering journal or on a mfgs website.
Just remember this, by your criteria of authoritative certification requirements, Einstein as a young man in his late 20s could not get a job with our Government today as much more than a laborer and Our Lord could not qualify for a Commission in the Chaplains Corps (I hope I used the proper nomenclature) in any branch of the armed services.
Edison would not be eligible either.
Beginner

[LI Pets]

Bottom line is you are incorrect about ST tires, you must stop repeating that information.

That question was asked by you to tell us the ratings of our tires, didn't need you for that thanks.

Those are tires that came from GMC on the truck and at $140 per are not a lot of money.

Not towing, I will from time to time go faster.

You said "As per LI Pets request I will endeavor to find the information from a engineer or engineering journal or on a mfgs website."

You tried that line many times here before about talking to some engineer, forget it .. that's unacceptable.

I would like two authoritative sources to support your theory

[Action]

OK so we know your two opinions and they don't mesh. Unless either one of you are going to present new data, please do not make statements about how the other is wrong. Or any other type of judgements.

>>>>>>>>>>>>>Action

[jcanavera]

Originally Posted by LI Pets

According the manufacturers spec sheets you're incorrect.

You can exceed 65 mph with ST tires, that is stated clearly on their inflation charts.

lso "the rubber compounds used to construct ST tires looses its integrity at a lower temperature than LT tires"


I just don't want others reading this miss info and buying worse yet inflating their tires incorrectly.


You can drive faster than 65 MPH but in order to do that, however, you need to increase your cold inflation by about 10 psi (without exceeding the maximum PSI stamped on the tire) for every 10 mph over 65 that you are going.

So if your chart indicated you needed 45 psi for your weight and you added 10 psi (or 55 psi) your rating is now 75 mph, if you added 10 more ( 65 psi) your rating is 85 mph.

Mine called for 50 psi on those charts, I run 65.

I often travel on good roads at 70-75 mph over the last 3 years and maybe 30,000 miles.

This information is provided at the Goodyear web site.

Industry standards dictate that tires with the ST (Special Trailer) designation are speed restricted to 65 mph under
normal inflation and load conditions, unless a different speed restriction is indicated on the sidewall of the tire.
Based on industry standards, if tires with the ST designation are used at speeds between 66 and 75 mph, it is
necessary to increase the cold inflation pressures by 10 psi above the recommended pressure for the load.
• Do not exceed the maximum pressure for the wheel.
• If the maximum pressure for the wheel prohibits the increase of air pressure, then the maximum speed must be
restricted to 65 mph.
• The cold inflation pressure must not exceed 10 psi beyond the inflation specified for the maximum load of the tire.

I want to add some clarification here. First there is no blanket rule that states that you add 10 lbs for every 10 miles per hour that you want to exceed the max speed rating of the tire. I've included Goodyear's statement that only supports 10 psi over sidewall limitations.

I have been to a tire training safety seminar that is put on by A Weigh We Go which promotes RV tire safety. MotorHomeAdvice.com - Articles >

The key issue is here is heat buildup in tires and the amount of flex that the tire generates. The faster you go, the more heat you build up in the tire. The lower the pressure, you increase the flex and again a byproduct is heat.

Speed rating is important since it indicates the tires ability to withstand heat and dissipate that heat. The reason why Goodyear states you can increase the inflation load by 10 psi is that the tire will have less flex which offsets the higher rotation speed (which increases the amount of flex and heat generated). Another example of speed issues is the fact that Airstream states you can pull a trailer with one tandem tire missing. Note however they limit the speed to 45 mph and 50 miles. Why? Because a tire rotating at a lower speed has a higher load limit and therefore the heat load generated by the increased load (and greater tire sidewall flex) is offset by the lower rotation speed.

So we can talk till the cows come home but ST tires do have advantages over LT's, one being UV protection (more), and sidewall flexability (ability to handle the pivot that occurs on tandem axles on tight turns). The liability side though is the speed limitations. And once you exceed the speed limitation stamped on the sidewall (without that 10psi adjustment), you increase the sidewall flex (due to the tires turning faster). That generates heat and those tires do have heat limitations. Whether it's the rubber compound, or the construction method, its physics. So if you want to drive fast, put on an LT. Obviously it has it's limitations but speed won't be the major factor.

Jack

[2airishuman]

...Speed rating is important...

YES IT IS!

but only for tires that CARRY a speed rating.

and ST TIRES DO NOT HAVE A SPEED RATING...

that is the problem with the 100s of posts by one person and the 1000s of posts that repeat this FACTUALLY INCORRECT INFO...

ST tires are LOAD RATED at the industry standard (for st tires) of 65 mph.

in other words the LOAD RATING is established at 65 mph.

but THEY ARE NOT SPEED RATED following the standard approach to speed rating.

http://www.airforums.com/forums/595219-post42.html

IF they were speed rated (using the accepted techniques) gy would NOT give any guidance on towing faster than 65mph ...

because BY DEFINITION exceeding a GENUINE SPEED RATING by 10 mph, WILL CAUSE THE TIRE TO FAIL within 10 minutes.

that is HOW current P/LT tire speed ratings are established.

tires are taken to a given speed and pushed TO FAILURE.

that isn't how gyms are tested and it isn't how they are rated.

most tires that are labeled P or LT are speed rated BUT NOT ALL tires are speed rated.

and NO currently produced domestic market ST tires carry a speed rating.

Tire code - Wikipedia, the free encyclopedia

P and LT tires (almost all) carry UTQG ratings now too, but ST tires are NOT utqg rated, just like they aren't SPEED rated.

now for a PERSONAL OPINION on SPEED and LOAD with regard to ST tires...

-weight EACH contact point on the trailer, IF any exceed the tire or wheel rating, FIX THE ISSUE...

-IF the load is VERY CLOSE to the tire LOAD RATING be careful about going over 65 mph.

-IF the load is UNDER the LOAD RATING significantly (several hundred lbs) then be sure the tire is INFLATED to max sidewall pressure before towing OVER 65 mph.

-HIGHER speeds may ACCELERATE wear or REDUCE load capacity...

-don't come crying here if ANYTHING bad happens towing at higher speeds, it was YOUR choice.
__________________________________

it's a bit like the confusion rdm' tired to clear in post #4 about plys...

and FOR THE SAKE of DIESEL EAGLE (the o.p) expanded a bit here...

http://www.airforums.com/forums/433671-post3.html

and here...

http://www.airforums.com/forums/f438...ply-35173.html

and here...

http://www.airforums.com/forums/f438...tml#post595219

D vs E is REALLY the topic of this thread BEFORE IT WAS HIJACKED in post #11...

with the REPEADEDLY incorrect info about speed ratings that DO NOT EXIST for these st tires.
__________________________________

imo the ONLY thing LI' is doing is asking for CREDIBLE references for the bogus st info, regularly posted by another member.

'pets is doing everyone HERE a favor by questioning this incorrect and MISLEADING stuff about st tires.

many of us have offered posts to COUNTER this incorrect stuff or have asked for REFERENCES.

but we eventually tire of trying to balance the BAD info with good, and the BAD just keeps getting posted OVER and OVER.
__________________________________

on a RELATED issue,

there is a difference between tires with an st tire LOAD RATING and a P/LT tire LOAD INDEX...

this is ONE of reasons why trying to select and use LT tires for towing is tricky,

because the LOAD INDEX of LT tires doesn't EQUAL the LOAD RATING of ST tires...

folks confuse this issue regularly which is understandable, but WE do NOT need to perpetuate it...

just like we don't need to perpetuate the MISLEADING NON-EXISTENT speed rating for ST tires...

__________________________

here's an example of ANOTHER passenger tire vs ST tire issue...

drivers may discover a P/LT tire is under inflated while driving, for example 10-15 psi UNDER the recommended pressure, way 35psi...

those LT/P tires that are under inflated by 30-40% can be correctly inflated and continue IN SERVICE.

but an ST tire that is used for as little as 50 miles UNDER inflated by 30%, SHOULD BE REPLACED, not used...

this is a critical issue, because LOTS of folks tow on 1 or 2 under inflated ST tire, eventually ADDING AIR and continuing to use it...

DOING THAT is against ALL of the ST tire guidelines and is probably why THOSE TIRES (used after under inflation) FAIL in service.

so ST tires vs LT/P tires are used, abused, replaced and inflated under DIFFERENT GUIDES and their service life and parameters are DIFFERENT.

yet how many folks HERE routinely REPLACE a newer or well 'tread' ST tire, just because it's been used some UNDER inflated?
________________________

back to the never ending threads on hot topics,

try looking at this whole thing from another angle...

IF someone was repeatedly posting that a/s trailer skin panels are GLUED together (the rivet heads are cosmetic only) ...

or that ALL a/s trailers are SQUARE...

would those misleading bits be allowed, OVER and OVER and OVER again?
____________________________________

so does this post EXCEED the speed rating for the forums OR is INCORRECT info ok here, as long as it is posted NICELY???

cheers
2air'

[ROBERT CROSS]

Originally Posted by 2airishuman;

so does this post EXCEED the speed rating for the forums OR is INCORRECT info ok here, as long as it is posted NICELY???
cheers
2air'

NO.....You are well under the speed limit, and it was a VERY nice post.

think I'll go toe at 99

[jcanavera]

I will note that I fell into a terminology gap in stating speed rating vs load rating. 2air is correct in that load rating is the proper terminology. I think if you take my post and replace the word speed with load, the information given still carries the same impact.

While the term speed rating is incorrect I'm hoping that everyone does understand that speed in conjunction with tire pressures does affect load capacity of a tire which ultimately affects the lifespan of a tire. It's heat that kills the tire and if you drive faster that the load rating on the tire (and dependent upon the load you are carrying) that tire will heat up. If you under inflate (and therefore possibly overloaded) the tire will heat up and you stand the chance of breaking belt components due to excessive flexing.

Jack

[HowieE]

2air

Thanks for the post.

I have one question on the Tire Code tread you noted. They state "Prior to 1991 tire speed ratings were shown inside the tire size"before the "R" character. I could not find an explanation on that page as to where that code is shown now.

Studying my E rated 2680 lbs. rated Michelin LT 225 75 R16s I don't see any notation for speed or temperature. While I am sure they exceed anything I will need I ask this for others that may be running LTs.

[jcanavera]

Here's an article that will get you through the tire coding. Note that as 2air said, the ST tires are not speed rated so this will only help on those tires which are speed rated.
Tires 101: What Your Tire's Markings Tell You - Cars.com

[2airishuman]

Originally Posted by HowieE

...I have one question on the Tire Code tread you noted....I could not find an explanation on that page as to where that code is shown now.

hi howie

info is HERE along with other good bits

Tire Tech Information - How to Read Speed Rating, Load Index & Service Descriptions

basically the speed rating for tires that HAVE a speed rating is NOW listed AFTER the size info, and along with service/load info...

for example a 255/40R17 94Z tire has a load index of 94 and speed rating of Z. ( check the table for what 94 and Z represent )

the R buried inside the size info stands for RADIAL contruction

so gyms have this R for radial (225/75R15) and a LOAD RANGE (c or d or e) but NO speed rating letter/designation.

Currently Available Prices and Sizes

one interesting deviation is THIS tire which is apparently a 'euro towing' tire with either Q (99mph) or R(106) speed ratings, but only available as a 14 inch.

Currently Available Prices and Sizes

i've not seen that tire first hand and wonder IF it carries the ST symbol on the sidewall.

still it MIGHT be a useful replacement for 14s and an alternative to the gyms in 14.

folks DO use many other types of tires for towing besides the ST models and with a WIDE range of outcomes...

but any of those tires will conform to the RMA /UTQG /service-speed labeling IF they are P or LT tires...

and bias tires or LT tires fail too...

http://www.airforums.com/forums/f438...art-25929.html

cheers
2air'

[HowieE]

Originally Posted by Action

OK so we know your two opinions and they don't mesh. Unless either one of you are going to present new data, please do not make statements about how the other is wrong. Or any other type of judgements.Action

The 2 original posters have stepped aside and others have offered comments that may resolve the question.

The issue of tires is probably the single most important subject that could be discussed here. There are a significant number of RV, including Airstreamers that have no idea of how to manage their tires as far as selection, load, and pressure, removing comments that are supported by manufactures and government standards is not a way to resolve this issue.

[Alwhisman]

I have E's on mine I run at 65 PSI. I made the error of mentioning to my dad I was going to replace tires, so he did me a favor......

He had taken his 5th wheel in and thought he'd just pick me up a set. He was tickled and said the rep where he bought them said that was what I needed. I didn't have the heart not to use them, so.......When I replace these, it will be D's....which I wanted originally.

I didn't mention where he got them on purpose, lol, it was a local non chain tire store.

Al

[HowieE]

Originally Posted by Alwhisman

I have E's on mine I run at 65 PSI.
Al

I am assuming you have 235 15s on the trailer. Unless your trailer weights 9,340 lbs you are slightly overinflated.

Check the inflation charts.

[Alwhisman]

You got me thinking, so I went and checked, they are at 60. I hated running them too far under the recommended pressure, but definitely not running 80 in them. I can tell the difference in the harder ride as it is. I have a little over 3k on them so far....been thinking about moving them to my work trailer and getting what I want for Christine.

[ROBERTSUNRUS]

Originally Posted by Beginner

ROBERT SUNRUS, your tires are Speed Rated at 110T or a Speed Rating of 118 MPH according to the web site noted above.
Why are you wasting your money on those tires or do you drive the unhooked tow vehicles a 100 MPH?
There are tires available with a Speed Rating of K ( 68 MPH) and L (75 MPH) which according to your arguments would serve you just fine and are probably cheaper.
Beginner

Hi, Beginner. I understand where you are coming from, but heres my explaination.

(1.) I bought my Lincoln with 16,800 miles on it while it was three years old. My Lincoln originally came with Continentals on it.

(2.) Further investigating, I discovered that the Continentals that were on my Lincoln were recall replacements. Continental had separation issues.

(3.) I was getting ready for another trip, when I noticed the Continentals had cracks on the sidewall. The Continental factory rep was there that day, but was wishy washy when it came time for him to decide if they would warranty my tires.

(4.) I have always preferred Michellins and Goodyear tires; I bought the correct tires for my Lincoln in Goodyear because I didn't like the tread design on the same size Michellin. Price wasn't the issue. I bought the best our dealer had in Goodyear.

(5.) The Goodyear tires were the same specs as the Continentals and specs by Ford. I don't know for a fact that my Lincoln will go over 100 MPH due to electronic governor. I have driven it up to 80MPH and that is the fastest I plan to go, but never while towing my trailer. This is my everday car.

(6.) Like wise with my trailer; I tow it with the tires it came with. I Didn't like the looks of two of my Marathons, so I replaced them with two new Marathons. I haven't had any flats or separations yet so I will continue to tow them at 65/65. [65 lbs cold / 65 MPH]