G rated tires versus E

Hi,

After having seven E rated tires destroyed in seven years on two different fifth wheel campers, we're considering upgrading to G rated tires.

I've read several of the post here concerning tires and have checked made sure that the wheels on our current Jayco Pinnacle are capable of the 110 psi of a G rated tires.

The majority of the reason for this change is our two year old camper has already gone through three tires. From the research here I realize part of our problem is we often drive seventy miles an hour and the ST E rated tires are designed for sixty-five. Goodyear's G614 G rated tires max tire speed is seventy-five. Granted driving at the design speed, or higher,  could cause the belt shifting I notice on the E rated tires. But not all of the tires that were destroyed had any unusual wear before littering the highway with rubber.

The loaded weight of our camper is in the 13,250 range with seven thousand pound axles.

Any advice is appreciated.

The G614 are very popular on all types of trailers with 7k axle.
Also the Sailun S637 235/85-16 G at 3750 lbs capacity are another very good option and cheaper than the G614.

Both are a commercial grade all steel ply carcass tire made for regional commercial service trailers. They work great on RV trailers.

I'm not sure that a load range G will help any. You didn't state the tire size, so we have no idea how much weight carrying capacity you have in the present tires, but once you get a comfortable margin of load capacity, adding a LOT more doesn't do much.

With 7000 lb axles you want around 3500 lbs per tire plus some extra margin, say another 5%.  With the 5W weight you gave (13,250), the axles are only carrying about 10,600 lbs or 2650 per tire, so even 3500 lbs per tire gives you a huge safety margin. What is the tire size and the max load stamped on the sidewalls? How much more does an F or G add?

I think you identified much of your problem with the highway speed. The rest could be inflation pressure. If you aren't religious about maintaining the required pressure for the loaded weight, no tire is going to last very long.

Gary RV Roamer said:

I think you identified much of your problem with the highway speed. The rest could be inflation pressure. If you aren't religious about maintaining the required pressure for the loaded weight, no tire is going to last very long.

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These two points are exactly what I was going to mention.  The failure is not really due to the E rating on its own, you are just constantly pushing it beyond its limitations.  Heat is what kills tires, and the most common causes of overheating are excessive speed and underinflation... with overloading being thrown in for good measure.  Combine any of those factors and you are headed for that lovely experience [/sarcasm] of seeing shredded black rubber cascading down the road behind you.

Post the tire size you have, and we can figure out more about about what replacement brand/size/load range might suit you best.

I have not had a tire fail but looked into this as well when the tires on my fifth started to fail. I found splits in the tread during a post trip inspection. Along with the information already discussed here I also found that not all E rated tires have the same load rating. E is a range not a set number. The tires that came with the rig were 3500 lb tires. Many of the after market had ratings as low as 2500 lbs. I made sure the ones I purchased were at least the same or higher. The ones I purchased are 3750 lbs. Another thing that trips some up is the pressure in the tires. The ones I have now have 50 lbs on the side wall as the suggested pressure. This only provides a 2000 lb tire rating. Per the load/pressure chart for the tire you have to have 80 lbs in to get the 3750 lb rating. The folks that installed the tire filled them to 50 so if I had not checked before leaving I would have not made it far on those tires.

Thank you all. Duh, I apologize for not mentioning the tire size. ST235/80R16. The previous fifth wheel came with Goodyear Marathon's with a load rating of 3450 that I replaced when they either showed signs of belt shifting, or disintegrated. Our present fifth wheel has Towmax STR, same size, with a load rating of 3650. I'm very religious at keeping the tires at 80 psi, which is what the manufacturer recommended for both brands.

One of the 1 year old Towmaxes went flat after being on the road for ten minutes after setting a month. The other one has a belt **** which I now suspect is the speed we drive. The third tire that's blew on our two year old camper was an Autogrip after 500 miles that had sat in the basement of the both campers for three years. I wonder if the heat, even though out of the sun, made it age.

With a diesel the truck and camper cruise so easily at 70 and since that is the highway speed of most of the roads we frequent I drove that fast. I won't from now on. Covering 500 miles in a day will only take another half an hour at 65.

One thing in favor of the Goodyear G614s has a speed rating of 75 mph. Even though I'll slow down, if our speed builds to 75 on a downhill that I don't want to ride the brakes on, it will be comforting.

Thanks for the advice.

Thanks for adding the size info.

The G614RT only comes in Load Range g, so that ends that part of the discussion. And it's an LT tire rather than ST, thus the higher 75 mph speed rating. The 3750 lbs per tire is perfect for your axle ratings too, even though your current actual axle weights are well below that.

The G614 is an excellent choice and should put an end to your tire problems.

After the doing the research here, I realize if we slowed down we'd probably solve most of our tires issues. But for the piece of mind we'll probably spring for the G rated tires and still slow down. It's frustrating, and dangerous, to be changing a tire on the highway. In construction zones with no shoulder to pull off onto, we would back traffic up for miles. Talk about pressure.

The tire issues were making us consider getting out of RVing, even though we love it. The people at campgrounds are great, the settings usually peaceful, and the convenience of taking our dogs and not living out of a suitcase were wonderful. But the stress of when and where another tire would go was getting to us.

Thanks all for the advice.

Gary RV Roamer said:

Thanks for adding the size info.

The G614RT only comes in Load Range g, so that ends that part of the discussion. And it's an LT tire rather than ST, thus the higher 75 mph speed rating. The 3750 lbs per tire is perfect for your axle ratings too, even though your current actual axle weights are well below that.

The G614 is an excellent choice and should put an end to your tire problems.

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Gary have you ever owned a set of GY614 tires, being a MH owner I doubt it. I've had to sets of them on 7K axles and I would never recommend them to anyone. The last set lasted 2.5 years and for what they cost that isn't acceptable.

I would recommend going to 17.5 wheels and tires load range H, You will end up with all position high rib commercial tire.


Denny

but once you get a comfortable margin of load capacity, adding a LOT more doesn't do much.

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That is one of the best statements about tire capacity for a trailer I've ever read on a RV website.
 
Having several trailers on the road with 28 tires on the ground for over eleven years and 800k + miles I found out quick the folly of over tiring a trailer with close spaced axles .
I preferred a 10-15 percent reserve load capacity that way the tire could still be operated at max sidewall pressure for a cooler operating longer lasting tire.

The OP has been using a  80 psi rated soft sided ST tire on a 7k axle. Moving up to the 3750 lb/110 psi rated G tire will give more reserve capacity at 110 psi and a stiffer sidewall  for less parasitic drag and a cooler running tire.

The 2016 Pinnacle models offer the Goodyear G614 tires as an option.

I suspect that your 7000# axles were set at 6750# by Jayco to accommodate the ST235/80R16E tires. You can look on the tire placard to verify that. 

Gary have you ever owned a set of GY614 tires, being a MH owner I doubt it. I've had to sets of them on 7K axles and I would never recommend them to anyone. The last set lasted 2.5 years and for what they cost that isn't acceptable.

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No, not that model. But I did run LT235/80R16's when we had a 5W. I've forgotten the brand, though.

Be constructive. If you don't like the GY G614's, perhaps you could suggest a better alternative to Flywriter?

My biggest find is most tire damage is from improper inflation. Just inflating to max PSI stamp on the side wall isn't exactly a good idea either. A tire is suppose to sit flat on the pavement and have some softness to the tire to allow it to wrap around objects instead of being struck on a sharp edge and break the belts or blow the tire. I'm one of the few here on the site that has NEVER blown a tire yet. My truck has over 250k miles and the RV is over 15 years old (I've owned it for 5 years) and never taken any tire damage yet.

I simply inflate to cover the max GVWR of the trailer. So for example I've got 2 axles (4 tires) rated for 2980 @ 80 PSI Load Range E. RV is rated for 8,500 pounds.

8,500 / 4 = 2,125 / 2,980 = 0.71 * 80 = 57 PSI (Inflate 60 PSI).

If I inflate to MAX 80 PSI I would be capable of carrying 11,920 pounds of trailer I've only got a mere 8,020 scaled weight and 8,500 GVWR rating...

So even though the tires are rated for 80 PSI I only inflate to 60 PSI which allow the tires to give when it strikes hard objects, potholes etc. This should reduce the amount of tire failures.

Gary RV Roamer said:

No, not that model. But I did run LT235/80R16's when we had a 5W. I've forgotten the brand, though.

Be constructive. If you don't like the GY G614's, perhaps you could suggest a better alternative to Flywriter?

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I did, 17.5 wheels with load range H tires.

Denny

Sorry, rvpuller. I totally missed your suggestion!

The suggestion to use sidewall pressure applies primarily to factory-equipped trailer tires, which are nearly always barely adequate even when at their max load values. Like all "rules of thumb", it isn't perfect nor all-inclusive. You can always do a superior job by following the proper analysis & procedure rather than taking the shortcut.

So, if you change tires or wheels, all bets are off and you need to reevaluate the psi needed.

When I was having problems with my second set of 614G tires I talked directly with GY and I was told because of the dynamic loads that trailer put on tires to always run them at max pressure but I still had problems with them.

I never had a blow out with one of them but they would throw the whole tread and still had 110 psi in them, got tired of picking up pieces of my trailer so we made the change. We started with Sumitomo tires at first and now have two of them and two GY 6114, we had to go with the GY because that was all we could find on the road after a bad road and sidewall damage, the tires were on their 6th year and about 50K miles.

Denny

When I was having problems with my second set of 614G tires I talked directly with GY and I was told because of the dynamic loads that trailer put on tires to always run them at max pressure but I still had problems with them.

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Then I have to say then you doing something wrong. Either towing too fast, over inflating, over weight of the tire specs, etc. Simply your doing something wrong.

Weight wise you know the trailer will never exceed is GVWR or at least I hope you scale your RV once in awhile. If so then you can figure out the tire pressure required. I've ran Load Range G's on the pickup. Just because they are rated for 1100 PSI & 3750 pounds doesn't mean I need 110 PSI for a pickup. Those tires could carry 15,000 pounds for 4 tires the truck GVWR is just a mere 8,800. Just like the RV you don't need MAX pressure. Over inflation will make the tire swell in the center and create a hot spot through the center of the tire. Also like I said before striking sharp holes like pots holes or large object the tire doesn't deflect so blow outs occur.

Then most ST tires are rated for 65 MPH as a limit. If your continuing to tow at 65 MPH it just like running a engine right at red line. Eventually the engine will blow up just like ST tires do. You can't run your speed right at the breaking point tires and not expect to have a blow out.

Again all you are stating how many tire failures your having... It's a clue that your doing something wrong.

"Dynamic loads". Now there's some handy technobabble!  It means the loads change, right?

It should be obvious that the pressure has to be sufficient for the maximum load that will actually be encountered, so the crux of the matter is to make a reasonable estimate of what that max will be. If you know the max load is less than the sidewall max limit, you can and should use the lesser amount. If you don't know that for sure, you should err on the high side. If you don't have a clue as to to the actual max load, the sidewall max limit is the safest choice, since the negative effects of excess inflation are far, far less an issue the even the slightest amount of under-inflation.

Mopar knows his actual weights and what his tires can handle. I think he is saying that all vehicle owners should do the same (and I agree). But I, and I suspect the GY guy, also know that few will actually do so. Ergo the "rule of thumb".

I know my weights,  12600 on the axles with left side 500 heavier than the right both axles are close to the same. The axles have been aligned twice and the springs replaced a few years ago. Our trailer is on its 13th year with over 90K on it, just like others we travel with when they went to 17.5 wheels and tires their tire problems stopped.

The dynamic loads he was talking about is the stress the tires get from any sway because the axles are so close together and the overload condition that will happen going over dips in the road because of the long overhang behind the axles. They are different than your truck with tires on the corners.

I checked a few years back and from my tire dealer GY614G tires are not recommended for use on a LT, trailers only.

Denny