Another tire question

[JimnJulie]

Knowing I can always get good information I come with questions. In April of 2009 before we headed back north from our winter in Florida in our 2006 3400RL, I was removing the tire covers and noticed a bulge on the inside of our OEM Missions after 16,119 miles on them. WE replaced them with Goodyear Marathons. This April on the way home again just outside of Brunswick, GA one of the Marathons blew out. Very little damage to the Monty, just cosmetic underneath. Three days later just outside of Huntington, WV the tire next to the one that blew out started to go flat. I took it in the next morning thinking I had picked up a nail. They plugged it, didn't hold, they patched it, didn't hold, they then put a tube in it and on the balancer it just about flew off. The belts inside had separated and if Julie hadn't needed the facilities of the rest area I would not have noticed the tire going down and it would have blown in just a few miles. I have read about the G614's (but they are made by Goodyear, and so were the Marathons) so I was wondering if I should get truck tires for the Monty or just buy more trailer tires.

[1retired06]

There has been much discussion of the Goodyear Marathons (bad) and the Goodyear G614s (Good). My advice is to stay away from any trailer tire, and stay far away from Goodyear Marathons. Go with a good quality LT tire E or G load. Our first two Montanas came with LT Tires, although they were no brand, and I swapped them out immediately for better quality E Load LT tires. For the past 8 years, I have been running Firestone TransForce LT tires, and have had no tire issues. Your 2006 rims may not be able to handle the G load tires, my 2002 and 2005 rims could not. If you are uncomfortable with using LT tires, MAXXIS makes a pretty good quality trailer tire, but not sure if available in the E Load rating.

[steelpony5555]

Several high end coachs come from the factory with LT tires. If you read on the forums there are very few if any problems with LT tires and numerous problems with ST tires no matter what brand. Going with the G tires is a good option but expensive. LT's are only a slightly more then ST's

[mhs4771]

We went with the G614s, but our rims were rated to handle the pressure. Approx 20K miles on them with no problem. There are many good LT tires out there that will give good service.

[TLightning]

IMHO, 614s are over kill, I went with LTs.

[JimnJulie]

Thanks a million headed out to the tire store now!

[DQDick]

I post this every so often, but it's spring so it's time to put it out again. Here's the story on why the Marathons don't do it and some ideas of what will.

I have asked many times for someone to explain how a ST tire can be rated to carry more weight than a LT tire in a similar size, without a good answer.

The answer lies in what is called reserve capacity. To quote from Trailer Parts Superstore and this same statement exist on just about every tire site:

HEAVY DUTY 'LT' TRUCK / TRAILER TIRES
'LT' signifies the tire is a "Light Truck/Trailer" series that can be used on trailers that are capable of carrying heavy cargo such as equipment trailers.

If a tire size begins with 'LT' it signifies the tire is a "Light Truck-metric" size that was designed to be used on trailers that are capable of carrying heavy cargo or tow vehicles. Tires branded with the "LT" designation are designed to provide substantial reserve capacity to accept the additional stresses of carrying heavy cargo.

So what is reserve capacity? It is capacity beyond the rating of the tire, capacity that is held in reserve. This reserve capacity comes from the heavy-duty sidewall of the LT type tires. LT's rank at the top of the list when we look at P, ST and LT tires.

Now I finally have an answer to how a ST tire can be rated to carry more weight than a LT tire of similar size.

The ratings of ST tires infringe into the reserve capacity of the tire. This is double bad, because the design of the ST gives us a tire with less reserve capacity to start with as it has a lighter sidewall to start with as most ST tires are much lighter than their LT counterparts.

To quote one tire site:
"Put a different way, the load carrying capacity of an ST tire is 20% greater than an LT tire. Since durability is strictly a long term issue - and the results of a tire failure on a trailer are much less life threatening than on a truck - the folks that set up these load / inflation pressure relationships allow a greater......ah......let's call it load intensity."

There it is in print to be read. They make a calculated decision to give the ST tire a higher load rating because a failure is less life threatening.

I have on a number of occasions pointed out the weight difference between the different tires and have been told that does not matter. Well it does matter. The rubber in the average tire only makes up around 40 some percent of its weight, the rest is in the steel belts, gum strips, steel beads, and the carcass plies. The remaining 60 or so percent of the stuff in a tire is what builds in the reserve capacity.

So to review again, here are some weights:
1. Michelin XPS RIB LT235/85R16 LRE (rated to 3042lbs) Weight 55.41
2. Goodyear G614 LT235/85R16 LRG (rated to 3750lbs) Weight 57.5
3. Bridgestone Duravis R250 LT235/85R16 LRE(rated to 3042lbs) Weight 60
4. BFG Commercial TA LT235/85R16 LRE(rated to 3042lbs) Weight 44.44
5. Uniroyal Laredo HD/H LT235/85R16 LRE(rated to 3042lbs) Weight 44.44
6. GY Marathon ST235/80R16 LRE(rated to 3420lbs) Weight 35.4

So which tires on the list have the most reserve capacity? Well that is not a completely simple answer, as one of the tires is a G rate 110 lb tire and the rest are LRE at 80lb inflation. So if we disregard the G614, then the Michelin XPS RIB and the Bridgestone Duravis R250 due to their all-steel ply construction will have the most reserve capacity inherent in their construction. The twin Commercial TA and Laredo will be next and the Marathon would have little or no reserve capacity available because it was used up in its higher load rating, AND because of it's much lighter construction it had much less inherent reserve capacity to start with.

So what have we learn from this?

I think that the first thing that we learned was that a LT tire can be used at or near it max rated loading without having issues, as they built with "substantial reserve capacity to accept the additional stresses of carrying heavy cargo".

The second thing we may have learned is why ST tires are failing on mid to larger 5th wheels, in that they do not have inherent reserve capacity beyond that rated max loading. Again this is because they have less reserve capacity to start with and their greater "load intensity" used up any reserve capacity that might have been available.

Now, here is an interesting bit of information. I just called Maxxis Tech Line and asked the weights for two tires.

ST235/80R16 LRD 3000 lb rating at 65 lbs of air weights 38.58
ST235/80R16 LRE 3420 lb rating at 80 lbs of air weights 43.43

What??? The Maxxis load range E tire weights almost the same as the Commercial TA?? This is a ST tire that has heavier construction than the GY Marathon at 35.4 lbs. So it has more inherent reserve capacity due to its heavier construction.

Those that claimed its virtues maybe did not know why it was a better ST tire than some of the others, but there it is! It is a heavier built tire with more reserve capacity.

So as one chooses a replacement tire or is asking for an upgrade on a new trailer please get educated on where the reserve capacity exist. Is it inherent in the tire you choose or do you have to factor it into the weight rating of the tire you choose.

Those with heavy trailers that are switching to 17.5 rims and tires rated to 4805 lbs and getting a double injection of reserve capacity, in that they are using a tire with lots of inherent reserve capacity and the tire has much more capacity than the application. It is all starting to make sense.

[mhs4771]

How much you want to bet that some of those folks switching to the 17.5 rims and wheels still only have 7K axles???

[tim43]

I put on new steel rims and then installed five 614s and it sure is a good feeling with them on the rig. Might be overkill, but it is an investment I thankfully can afford.

[bigred715]

I will never buy a Goodyear tire again after my experience with the Marathons that came on my new trailer. Have Michelin tires on both the truck and trailer. The trailer tires were only a few more dollars than Bridgestone that Discount tires had and the 5 Michelins had a $70 rebate. If Goodyear is willing to have tires built in China and sold here in the U.S. they don't have my respect as a good company and have lost my business forever.

[Bigboomer]

Dick,

Excellent explanation. This should be attached to every owners manual so all of the folks can be educated on the do's and don'ts in the tire world!

[DQDick]

Don't think keystone would want to openly point out how crappy the original equipment tires are.

[Bigboomer]

Yeah, can't see that either....Silly Me!!!!

Goes back to Caveat emptor!

[dreamers2010]

Where is everyone getting the larger wheels for the G614s?

Judy

[Tom S.]

OK, time to chime in (again). Tires for trailers have one primary function - carry the weight that is put upon them w/o going boom or flat. For that reason, someone with one Montana model can't honestly tell someone with a different model what will work and what won't. Heck, depending on how much cra.... er, stuff you put in your Montana, the same tires may or may not work even on the same model, especially when you take into consideration different options.

Where am I going with this? Some folks have seen me post this before, so you may skip ahead or disregard. The only safe way to determine how much tire you need is to weigh your loaded rig, one wheel at a time to find out how much weight each tire must carry. An easy way around this is put a tire on you know your rig's weight won't exceed, and many have done this by going to "G" rated tires. What this means is unless you buy a Big Sky with every option and then load it with lead, you'll never have to wonder if you have 'enough' tire. That's not a bad option, but it's not a cost effective one. By weighing your rig, you may find out that an "E" rated truck tire will be within the limits, and that is fine. And while we're talking about "E" rated tires, I'll again state (as in previous posts), not all "E" tires are equal. An "E" rated truck tire in the size needed for Montana's will be rated around 3,040 pounds, while an "E" rated trailer tire the same size will be rated 500 to 600 pounds more. This is one time when being a weight um, er, Policeman is a good thing. Between truck and trailer tires, there's another difference. Speed ratings with truck tires higher than the trailer tires 65MPH.
Size for size, trailer specific tires can handle more weight, but suffer more from heat build up, due the extra cords used to give them their rating. Truck tires have fewer cords, which means less friction, which equates to less heat, and therefore higher running speed (before heat becomes an issue for them too).

I hope this helps clear the air (pun absolutely intended) on tires!

[Tom S.]

OK, post #2. Why does Keystone put these worthless tires on in the first place? Let me begin by saying I don't, nor have I ever, worked for Keystone. But I have spent a few decades in connection with the auto industry, including part suppliers. When you are a manufacturer, you have to plan at least a year in advance for what materials and purchased items you are going to use on your end product. This has to be done to sure continuity of production. Auto companies usually work three years in advance, due to the complexity of their products and the numbers involved.

Trailer tires, like many other items once produced in our great country, went to China to take advantage of low wages and nearly non-existent regulations. What can a manufacturer like Keystone do when every supplier of tires has done this? Nothing. Therefore, there were only two possible outcomes, and neither one an ideal cure.

Outcome #1: Keystone signed a contract with a supplier who promised, via a written contract, to supply a tire that would meet or exceed their expectations. We all know what the outcome was - tires that failed at an abysmal rate. So the first question fired at Keystone was: "What are you going to do about it?" Well, what can they do? Reality sets in at this point. Keystone can't tell the supplier that they have a contract and to go pound sand. The supplier undoubtedly had the right to A). determine if a problem did exist, B). determine the cause of the problem (remember the Ford and Firestone fiasco?), and C). offer a solution. None of this happens overnight. You also have to realize that you can't pick up the phone and find an instantaneous source for a huge amount of tires. Worse yet, had Keystone stopped accepting Mission tires, there wouldn't have been any Montana's built for a long time. Regardless, for quite a while the supplier was making good on replacements, provided owners brought it to their attention. In the meantime, you know that Keystone wanted a better supplier, but again, with all brands being made in China, the options were few. Keystone, BTW, got an earful on this subject at every rally I've attended, plus some before my time. At this point, someone at Keystone made an executive decision to go with an American company, even if the product was produced in China. There is sound logic behind this move. The new supplier has an excellent world-wide reputation in the car and truck field, and has been around for 100 years, which one would hope would mean far better design and quality control. Thus Goodyear became the supplier. Alas, we all know the miserable performance they have been providing.

Outcome #2: So once again, Keystone is faced with a difficult decision. Look for another supplier, or start using higher rated tires and wheels on their products. To some degree, they have chosen the latter, but it was with increased cost to the consumer and the company. There are many of us who would gladly accept this cost, but the RV market is still in a precarious position. While having survived the recent depression, Keystone still has to put value at a high priority. To many of us, $2,000 extra isn't an issue but to others, it's a deal breaker. Consequently, I'm betting Keystone is still looking for a quality supplier in the "E" trailer tire load range. I for one hope they find one.

[1retired06]

When you cut through all the detail, the bottom line is ST tires are failing at a much higher rate than E or G load LT tires.

[bigmurf]

Reminds me of the old question:: Why does GM put a $2.00 jack in a new car? Because they ran out of $1.00 ones.

[exav8tr]

quote:Originally posted by TLightning

IMHO, 614s are over kill, I went with LTs.

IMHO, You can never be TOO safe. One doesn't have to pump them up to 110 psi to enjoy a great ride. We just have to agree to disagree.

[exav8tr]

So to review again, here are some weights:
1. Michelin XPS RIB LT235/85R16 LRE (rated to 3042lbs) Weight 55.41
2. Goodyear G614 LT235/85R16 LRG (rated to 3750lbs) Weight 57.5
3. Bridgestone Duravis R250 LT235/85R16 LRE(rated to 3042lbs) Weight 60
4. BFG Commercial TA LT235/85R16 LRE(rated to 3042lbs) Weight 44.44
5. Uniroyal Laredo HD/H LT235/85R16 LRE(rated to 3042lbs) Weight 44.44
6. GY Marathon ST235/80R16 LRE(rated to 3420lbs) Weight 35.4

The key to these numbers is that every time you hit a large bump in the road it increases the load on that wheel, therefore increasing a chance of a blow out. Of the tires listed, only the Goodyear G614 and the Marathon are rated above 3400lbs. Now we all know where the Marathons are made so that leaves the G614's............................................ ........... Of course, if you only travel the nations smooth highways this should be no problem, RIGHT? While I would never tell someone how to spend their money, my money is, and has been on the GY G614's.