G vs E?

[captbanjo]

The 3750FL we are looking at purchasing has E rated tires. I realize the G rated ones are superior, but just how and does anyone (I'm sure someone here does) know what that means in real-world terms?

Is it worth me asking the dealer to change the tires out at my cost?

[bncinwv]

What I did when we purchased our 3750 is I made it clear to the dealer that the 3750 was not leaving the lot with the Marathon's on it. After some negotiation, they agreed to replace the Marathons with 614's for an agreed upon difference in price. They bought the 614's at Sam's Club and I paid the difference less what they credited me for the Marathons ($500 - they were classified as used due to the delivery). After experiencing failures and reading about even more on this forum, I will not pull a heavy Montana (the 3750 is a heavy one) with the words "Made in China". This is not a recommendation, just relating our experience and my personal preference. We have towed with the 614's for more than two years now with no problems at all. The 614's are rated at 3750 pounds each and the marathons are at 3420 pounds. The marathons are only speed rated to 65 mph, where the 614's are rated at 75 mph. The forum has mentioned other G rated tires that are available, but we stuck with the "Made in USA" ones.
Bingo

[8.1al]

In real world terms the E rated Marathon tires are unreliable, many, many members have had them fail. While the G rated Goodyears are not totally indestructible they will give you many miles of worry free use

[DQDick]

There was a good article on tires going around a few years ago and I copied it and have it. If you'd like a copy email me at dqdick10432@yahoo.com The short version is that you can judge a tires reserve capacity by it's weight. Marathons weigh 35.4# each. G614's weigh 57.5# each. A lot more in material and belts in a G rated tire = more safety for you.

[Art-n-Marge]

Just realize that the E or G ratings are generalizations and only the sidewall will tell you what the tire supports using a real number like 3042, 3420 or 3650 which is the lbs a tire will support. I've seen all three of these numbers on E rated tires so the E doesn't automatically mean one number. Generally, G numbers would be higher, but it's about the real number where it really counts.

Whatever the size, G rated tires will do better than E rated tires, like what you're planning but check the numbers to guarantee they meet your need and at what required psi.

When you say dealer, do you mean RV dealer? Be careful that the dealer doesn't charge you more for the convenience than what it might cost at a tire store, especially discount tires stores that have the best prices. If you are going to change out the tires, make sure you pay the best price and it might not be your RV dealer.

[BB_TX]

I think the brand also makes a lot of difference, maybe as much so as E vs G assuming you are within safe weight ratings of the E.
Good friend replaced his Chinese Missions 2 yrs ago with Goodyear Marathons thinking because they were Goodyear they were US made. Wrong. He was not happy when I showed him "Made in China" on the sidewall. Had a blowout on one last year on the way to Colorado doing some damage to the fender skirting.
Unfortunately he passed away last fall. But his wife, daughter, and son-in-law took the trailer to Colorado this year. They had two more blowouts on the Marathons. Don't know the details yet or if there was any/much damage.
I don't see reports like that on other brand E rated tires that have been recommended by others on MOC.

[1retired06]

We have run E Load quality truck tires for years without problems. G is better, but for us, overkill. E Load LT tires have worked just fine. Marathons of course are a non-starter.

[Irlpguy]

For starters: every tire sold in America and Canada "must" have a DOT (Department of Transport) stamp on it. Likewise every tire must have the tires load capacity @ maximum air pressure stamped on it. There are a number of other things mandatory but the most important are the DOT load rating and air pressure.

A good many years ago tires were rated by the actual number of ply's in the sidewall of the tire. At some point a standard was developed where an alphabetical rating was developed to indicate the tire was "rated" at 10 ply (E) or 14 ply (G) and so on. That means only that the tire might have only 6 "actual" ply's but with new materials and designs it could then be rated at 10 ply or whatever.
The alphabetical reference is with respect to "ply rating" of the tire.

On this forum and others you may see references to "reserve capacity" and in most instances the information is incorrect and riddled with inaccuracies.

The DOT capacity of a tire is what it is rated to carry and stamped on every tire, it does not matter if it is a P passenger, LT or ST tire, that DOT rating is it's capacity at the maximum air pressure also listed on the tire. There is no reserve beyond that number, but what has been circulated suggests there is more "reserve" in an LT tire than in a ST tire which is simply not true.

DOT regulations require that the weight on all drive wheels on a passenger carrying vehicle "must" not exceed 94% of the max capacity of the tire.. This means the vehicle and it's load cannot exceed 94% of the capacity of the tires used. Reserve Capacity is the 6% that is required on those vehicles only. The DOT does not require that a trailer manufacturer reserve any amount of the rated capacity of the tire and may show a capacity up to the full amount stamped on the tire. Therefore no reserve.

The differences stated above do "not" in any way give a LT tire more reserve capacity than an ST tire. Anyone who questions this should look up the DOT regulations.

With respect to lighter RV's with 6000 lb axles or less then they can use a LT tire which will not diminish their axle capacity by using them. The LT tire is rated for higher speed and many have steel sidewalls and have been recommended many times by folks who are using them and fellows in the tire business. I think you are far better off to go to an LT tire on lighter units. They will last longer and will not be damaged by exceeding the 65 max MPH on a ST tire.

I would not put an E rated LT tire on any trailer that has 7k axles, and in fact believe it to be illegal. That is my opinion and I have not been able to get an answer from the proper authority in the US, but I do know it is illegal in several if not all Provinces in Canada.

If your RV has a GVWR approaching 15,000 lbs and has 7k axles I would recommend changing the tires to a G (14 ply) rated tire.

Before anyone starts a war with me, I apologize to DQDick because he has mentioned this previously circulated article, but it has been debunked by others who have stated the DOT requirements and numbers that are the same as I have stated above. I would post one or more of those challenges here but they are too lengthy.

Get the best tire you can afford, do not use a tire which is not rated for the load you are likely to carry. Do this and I think you will have many happy miles.

[richfaa]

we have a great tire guy here on the forum who owns a tire shop and should know the answer on "reserve capacity" I have seen that term used for tires and also trucks and have had experts in both fields tell me it was not so.

[bncinwv]

My take on "reserve" capacity is if I have tires that will support a 3750 pound load (G614's at 110 psi) and I have them on 7000 pound axles, then my tires have a reserve capacity of 500 pounds per axle or a 1000 pound cushion for my rig. If I have tires that support a 3420 pound load (Made in China Marathons at 80 psi) on 7000 pound axles (rated at 6750?? yet they are the same axles??), then I have no reserve capacity. Do the math and odds are with close to a 16,000 pound rig, you will most likely reach the same conclusion that I did, the Marathons or any "E" rated tire don't get it. The only thing I know for sure is that whatever "reserve" capacity is defined as, I feel a heckuva lot better knowing that I have tires that will own up to the job they were purchased for. I have had chunks fly off of the China specials (Missions), I have had blowouts on the replacements (Freestar) and I was not going to give the China made Marathons a chance. Make an informed decision based on common-sense math and you will not be disappointed and if you are like me, won't even give tires a second thought (which is exactly where we all should be when towing). These threads that seem to migrate towards the opinionated views of "I know better" or "you are wrong" serve no purpose other than to confuse those members who are seeking legitimate advice. This is all based on the premise that members who are seeking advice should realize that they are receiving opinions, which are worth about a half cup of coffee! And that is my opinion!!
Bingo

[Irlpguy]

Bingo has hit the nail on the head, if you concern yourself with buying tires that give you a fairly significant amount of carrying capacity above the rating of your axles and the load you will carry, then you can call it whatever you want, call it reserve capacity, unused carrying capacity, whatever. Having tires that are rated for the speeds a lot of people travel today, and which exceed the load we are going to be carrying, will make your traveling life safer and less stressful.

The DOT rating on any tire is the Maximum load at the specified maximum pressure that the tire is rated to carry. There is no hidden reserve in an LT tire as opposed to an ST tire, that is it, there ain't no more. A LT tire rated for 3042 lbs is rated for 3042 lbs and no more.

You would get little argument in this forum that the offshore tires are inferior to those manufactured in the US, the sad fact is the RV industry puts those tires on all of the RV's they sell, with the odd exception it would seem. The ST tire is only rated for 65 mph, they are not manufactured to handle speeds in excess of that. Combine excessive speed with tires that are rated to carry only 3420 lbs and are near their max anyway and you are asking for trouble.

The OP asked: Is it worth me asking the dealer to change the tires out at my cost?

My "short" answer is Yes, Yes, Yes. You should receive some trade in value on the Marathons that come with the 3750FL

There are alternatives to the Goodyear G614 that are "G" (14 ply) rated tires which are less expensive, one is the (Geostar G574), do some research on those, but if you want a tire that has proven to stand up and is made in the US then bite the bullet and get the G614's. I have about 9000 miles on my Marathons but the G614's will be going on my rig before my next trip to Arizona, in part because the others are not easy to get here in Canada.

Caveat: This is only an opinion and not worth the half cup of coffee referred to by Bingo...

[richfaa]

Bingo's definition of what " reserve capacity" means to him makes sense to me.

[Captain Joe]

Bottom Line: The 3750FL needs "G" rated tires. In less than 3 years, 3 of my 5 "E" rated tires are now junk. The "E" rated tires meet the BARE minimum for the 3750FL, that is how they are justified to be on the RV. I bought new "G" rated G614s manufactured in April 2013 and still had the dealer swap out his 2012 G614s for mine on my new Big Sky. Dealer said: "No problem." On new RVs, your tires could be almost a year old before you even take delivery. You will not wear out a G614, before its age (normally 5 years) requires replacement. That is why I had them put on my NEW G614s.

[captbanjo]

Thanks to everyone who contributed to this topic. Very helpful!

[WaltBennett]

No one's mentioned tire age and how it affects those numbers stamped on the sidewalls. I've heard one manufacturer state that a tire looses 10% capacity per year and another and I've seen a report from another that it's between 10 and 15%. If you're running on over 5 year old tires and at 16k weight, you're looking for trouble no matter where made or what rating. I've an 8 year old E rated Marathons on my 3k gross utility trailer that work fine, but I very seldom have even 1k weight in it. Our old '07 TT had the original E rated Marathons that never gave any problems (well, the valve stems did rot out a year before we traded it in), but it was only 10k max.

Bottom line to me is that tire age is almost as important as rating or numbers.

[KathyandDave]

I was told that the marathons are expected to last about 10,000 miles. By someone who would know. Ours lasted about that long. We never ran them above 60 mph and never loaded the trailer over 15,000 lbs. On the way to a goshen rally, we had a hard stop in Kalamazoo that took the tread off down to the steel. We're on G614's now.

[Chip]

A little story:
I was in CW in NH recently and this guy just signed papers on a new Montana 3582, trading in his HR. I notice the new Montana had Marathons on it and his HR had fairly new G614s. I asked him if he new about the Marathons and he said no. So I told him about the MOC and the history of this tire and that he should go back to the salesman and have them trade out his tires, putting his used G614s onto his new Montana. He did this and was very appreciative of the information. Dealer did this for him at no charge.

[JacknBetsy]

We had our third blow-out today so we are reading these posts with much interest. We have E-rated, 235-80-16 on our 2009 3400. If we go with the G614s can we use the same rims? Do we need to change all 4 tires at the same time?

[moutard2]

quote: There is no hidden reserve in an LT tire as opposed to an ST tire, that is it, there ain't no more. A LT tire rated for 3042 lbs is rated for 3042 lbs and no more.


I'm not questioning anything that has been stated here however I am curious as to the source of the "facts" as outlined in the posts particularly the post that states that there is NO reserve capacity.
Personally I believe that there must be some kind of built in "reserve" because each tire experiences different loading factors as we motor down the highway. Have you ever hit an expansion joint or other road hazard that caused your trailer to shift onto one side or the other? I would think that this movement would cause a significant load increase on one side thus the need for a "reserve" capacity. Don't shoot .... I'm just thinking.

[moutard2]

quote: There is no hidden reserve in an LT tire as opposed to an ST tire, that is it, there ain't no more. A LT tire rated for 3042 lbs is rated for 3042 lbs and no more.


I'm not questioning anything that has been stated here however I am curious as to the source of the "facts" as outlined in the posts particularly the post that states that there is NO reserve capacity.
Personally I believe that there must be some kind of built in "reserve" because each tire experiences different loading factors as we motor down the highway. Have you ever hit an expansion joint or other road hazard that caused your trailer to shift onto one side or the other? I would think that this movement would cause a significant load increase on one side thus the need for a "reserve" capacity. Don't shoot .... I'm just thinking.

[Irlpguy]

quote:Originally posted by moutard2

I'm not questioning anything that has been stated here however I am curious as to the source of the "facts" as outlined in the posts particularly the post that states that there is NO reserve capacity.
Personally I believe that there must be some kind of built in "reserve" because each tire experiences different loading factors as we motor down the highway. Have you ever hit an expansion joint or other road hazard that caused your trailer to shift onto one side or the other? I would think that this movement would cause a significant load increase on one side thus the need for a "reserve" capacity. Don't shoot .... I'm just thinking.


Ha Ha I am not shooting and I am glad you are thinking. Here is what I have researched and found on the NHTSA website: Specifically tires.

http://www.nhtsa.gov/Laws-Regs

Also specifically rules on this website:

http://www.nhtsa.gov/cars/rules/rulings/UpgradeTire/Final/Index.html#ref74 In particular the reference to part D. Tire Selection Criteria/De-Rating of P-metric Tires You have to read down a good number of paragraphs to the final ruling.

It is these references to tire reserve load that some have used a play on words to suggest an LT tire has a reserve capacity where an ST tire does not.

Unless I misunderstand this ruling after reading it over and over then what I determine it means is exactly as it states:

For passenger cars and for non-passenger car vehicles equipped with LT tires, the final rule requires that the vehicle normal load be based on 94% of load rating at the vehicle's placard pressure. Therefore, vehicle manufacturers will be required to insure that the tire reserve load corresponds with the tire's load carrying capabilities when the tire is inflated to the vehicle manufacturers recommended cold tire inflation pressure rather than the tire manufacturer's maximum cold inflation pressure shown on the tire sidewall. The 94% figure was chosen to approximate closely the load reserve that results from the current requirement of 88% based of load rating at the tire's maximum inflation pressure.

It refers to the tires reserve load capacity when it is inflated to the pressure specified by the vehicle manufacturer, rather than what is on the side of the tire as it did originally. The load reserve is built by the vehicle manufacturer because they are required to use only 94% of the tire capacity. There is no mention in all of these rulings that state the LT tire itself has more (or less) reserve capacity than an ST tire.

The difference and confusion is that trailer manufacturers do not have to use this 94% reserve when they rate the load capacity of the trailer, they can use 100% of the tires rating and put that on the placard on the trailer.

The original play on words that has been floating around this and other forums was originally posted by a fellow by the name of Barry Smith on Allexperts.com and further crap has been added by others. It has been debunked by others who have challenged those that promoted the so called "reserve capacity" theory to provide written backup of their claims. That to date has not happened, because there is none.

P and LT Tires cannot be compared to ST tires other than the fact that they both have the same DOT requirements stamped on them. They are built for a completely different application.

The LT tire that is DOT rated for a load of 3042 lbs cannot safely carry more than that. By only using 94% of that capacity a "reserve capacity" is created on those passenger vehicles as specified in the ruling.

By the same token an ST tire DOT rated at 3402 lbs cannot safely carry more than that. The difference is RV manufacturers do not have to reduce the DOT rated capacity which leaves no "reserve capacity".

There is literally hours of reading in these documents: some a bit hard to understand and somewhat confusing but these rules are what the legal profession would research and use in any lawsuit. Here is another site referencing sticker information regulations I found to be of interest.
http://lemon.onecle.com/fmvss-standard-no-110/

The "real" reserve capacity that we need to worry about on our trailers is the safe spread we have between what the tire is DOT rated to carry and what our load is likely to be at it's maximum, the greater the difference in those numbers the more reserve/safety we have.

Once again I will state I am absolutely no expert on tires and do not claim to be one. This is how I and others have interpreted the NHTSA rulings with respect to load reserve/capacity. Read some or none of this material, agree or disagree we are all free to do that.

[Irlpguy]

Moutard2, just to comment on hitting an expansion joint or other road hazard. When we are running on tires that are basically at their maximum load capacity and something like this happens damage can occur but not cause a blowout to the trailer tire at that time, by the same token it can happen on a LT or P tire as well. Alone it might not be the straw that breaks the camels back.

I believe that we can unknowingly or knowingly hit something causing some damage, this damage may not manifest itself until quite some time later when we have driven many miles. I also believe that overloading and under inflation which both cause heat to be one of the greatest reason our ST tires fail. Speed is another factor.

Just thinking also, but do you think perhaps we could get a road hazard guarantee on our ST tires.

[moutard2]

quote:Originally posted by Irlpguy

Moutard2, just to comment on hitting an expansion joint or other road hazard. When we are running on tires that are basically at their maximum load capacity and something like this happens damage can occur but not cause a blowout to the trailer tire at that time, by the same token it can happen on a LT or P tire as well. Alone it might not be the straw that breaks the camels back.



Perhaps the expansion joint was not the best example. I wasn't trying to illustrate an example of when damage could occur but rather one where load (and thus weight) shift could occur. If my left rear trailer tire was running at maximum inflation and at a scale weight of maximum capacity and I hit a pothole on that side, I would think that there might be some kind of loading on the left side tires due to inertia, gravity, etc. and the load on those tires might then be at maximum plus something. Without any "reserve" capacity in terms of tire construction, material, etc., a catastophe could occur. I dunno ... maybe my thought process is way out in left field on this but we see examples of reserve capacities built into just about everything these days to allow for the "human" factor of pushing everything to the limit. OK, next topic!!

[moutard2]

quote:Originally posted by Irlpguy

Moutard2, just to comment on hitting an expansion joint or other road hazard. When we are running on tires that are basically at their maximum load capacity and something like this happens damage can occur but not cause a blowout to the trailer tire at that time, by the same token it can happen on a LT or P tire as well. Alone it might not be the straw that breaks the camels back.



Perhaps the expansion joint was not the best example. I wasn't trying to illustrate an example of when damage could occur but rather one where load (and thus weight) shift could occur. If my left rear trailer tire was running at maximum inflation and at a scale weight of maximum capacity and I hit a pothole on that side, I would think that there might be some kind of loading on the left side tires due to inertia, gravity, etc. and the load on those tires might then be at maximum plus something. Without any "reserve" capacity in terms of tire construction, material, etc., a catastophe could occur. I dunno ... maybe my thought process is way out in left field on this but we see examples of reserve capacities built into just about everything these days to allow for the "human" factor of pushing everything to the limit. OK, next topic!!

[Irlpguy]

There are documented cases of damage to rims in such a scenario with no apparent damage to the tire, most often however the tire is damaged and in some cases I guess the extra weight or inertia will cause the tire to fail. How much extra on any given tire would be hard to determine.

There are all kinds of tests done on passenger tires, but few if any on ST tires that I have been able to find. Perhaps an LT tire will take more abuse than a ST I do not know. I do know the DOT load rating on both is what is supposed to be the Maximum at the specified pressure.

I would just like to see some documentation either from a legal requirement or tire manufacturers requirement that says the LT has more reserve capacity than an ST tire.

Tires will be a never ending debate, yes next topic.

[Irlpguy]

For anyone interested here is a great site that gives all kinds of information on Passenger tires, nothing on trailer tires however it is interesting.

http://www.safercar.gov/Tire

If you look at "tire aging" for example the very last paragraph states that over 11,000 tow away crashes occur every year related to tire issues. That figure may not include trailers as the site is related to passenger type tires.