Tire Information

[Tireman9]

Rusty and others
Have you had your unit weighed with individual scale under each tire? If not there is data that indicates that you may have significant variation axle to axle and side to side. Even to the extent of LF and RR of a 2 axle rig being significantly heavier than the other positions.

If you only get the total load on all axles and assume uniform loading on all 4 or 6 of your TT tires you may be operating without accurate information.

It also seems possible that with use and wear the axle to axle loading can change due to wear and fatigue of the various suspension components which means that the numbers you got 3 years and 20,000 miles ago may no longer represent reality.

One advantage of having a margin to the load is that if the margin is sufficiently large it can compensate for the unknow imbalance R?F & Side to Side.

It has been suggested that in trailer application that you should always run the max inflation on the sidewall of the tire. This would help offset the issues with sway, high C/G and high lateral loading and the hidden load imbalance.

[FastEagle]

There are people of all levels of knowledge and experience participating In these RV forums. When it comes to tires for the RV trailer industry the average person browsing the forums for information is seeking answers for an unexplained tire condition. The percentage of people that operate motor vehicles and have experienced a catastrophic tire failure (blowout) is minute. Surveys have shown 50% - or more - of all vehicles have at least one tire 20% low on tire pressure. You can get away with that on a car or pickup but on a loaded RV trailer that low tire will soon fail. The average poster in these forums has already found that out. What they are looking for is a solution. It’s in your RV trailer’s OWNERS MANUAL. It’s in the vehicle certification information. It’s in the DOT regulations - if you have the time to dig it out. The information that is not in any of the above is the disservice many of the RV trailer manufacturers are legally doing to their customers. The most obvious to an experienced layman is the lack of tire reserve capacity the RV manufacturers provide to their customers. And that is flagrant. When tread separations appear and all mechanical causes are eliminated, speed, air pressure and weight must take center stage.

Do not confuse durability with load capacity. A retreadable tire is going to weigh much more than a like item from the same manufacturer that is not retreadable. Why? Compound density, taller treads and added sidewall protection, just to name a few. The two tires will still have the same load capacity. Until somebody changes the figures that’s what the layman has to rely upon.

I’m going to use a LT load range “G” tire in this hypothetical situation. A dual 7000# axle capacity trailer with a total of four tires has a GVWR 16,000#. The new owner loads it up and takes it to the scales. After all the numbers are crunched the actual GAW is 13,000#. The axles are equipped with LT235/85R16G tires rated at 3750# at 110 psi. Now we take the scaled GAW and add a 15% reserve load capacity. That comes to 3737# per tire, real close to the maximum capacity of the OEM tires. Now lets add in the error factor none of us can avoid with a tire that holds air. This number will vary depending on who derives it so I’ll use 1.65%. That’s the amount of load carrying capacity you lose for every pound of tire pressure lost from the maximum allowed tire pressure. Will that help to explain why the tires are failing? Not all of it but it should open eyes to the condition “bigger is better” when selecting replacement tires.

I use ST tires. I had to get to nearly 20% reserve above GAW before I could rely on my tires to last more than three years. Because of the way I now store my trailer I us a 1% degradation factor. It can be much higher than that and everyone will have to determine their own factor. Long periods of storage will increase the factor immensely. A 2.5% degradation per year would not be uncommon for long term storage in areas such as southern AZ. What that means is that a tire rated at 3000# could in fact degrade to just 2625# after one year in southern AZ with a six month storage stint. Experience in these calculations will vary and will have to be a trial and error thing. It’s all part of the tire aging process and no one wants to try and put factors on it.




FastEagle

[Ray,IN]

This is a very informative discussion folks!
I will relate my tire experiences for the month of July, with inflation at 80 psi. Traveled 1,500 miles with only a nail puncture. At 1,900 miles one (date code 0407) Triangle ST 235R80-16, LR, "E" failed due to ply separation. Two weeks later the other three all failed at the same time; again ply separation. The rated max. load in 3,100 lbs per tire, our 5er individual tire weights were 2,960#=LR, 2,900#=RR, 2,500# LR and RF. (BTW, had trailer raised to level position to eliminate axle/wheel weights discrepancy)
I hope I have eliminated such tire failure now. I have four new Sailun LT 235R85-16, LR "G" tires, installed by A&R truck repair and tire shop at Chamberlain, SD. Sailun is made by Sigma Tire to compete with Goodyear G 614 tires. Time will tell__.

[D&J]

Like Ray said lots of information but like him after multiple tire failures on two different sets of GY 614 I went with 17.5 H tires. Now instead of 15% safety margin I have a 35% margin, time well tell but after 4500 miles all's well.

Denny

[wingnut60]

Ray,
Let us know how they hold up--hadn't heard of Sigma brand. Is it US made?
Joe

[Ray,IN]

Originally Posted by wingnut60

Ray,
Let us know how they hold up--hadn't heard of Sigma brand. Is it US made?
Joe

Chinese Mfgr. Sigma has made HDT, light duty truck, trailer, and automobile tires for many years. Their Sailun line of HDT, and HD trailer tires are relatively new, made to compete with Goodyear mainly.

[Paul R. Haller]

I have had many 5er trailers... some have had tire issues. My experience has told me that ST tires no matter how good they look on paper, just don't last beyond about 2-3 years. I have also gone to load range G tires to prevent tire issues. In my opinion it's the trailer manufacturers that need to have their feet held to the fire here. They are the ones who put load range D tires ion a trailer that weighs in at 12,000 lbs saying that 20 % of the weight is on the truck, leaving 0 safety margin for tires even new.This is dangerous and they play this game because we as consumers allow it.

Vote with your pocket book and do not buy trailers whos running gear is rated lower then the total weight of the trailer! Brakes, bearings, axles, springs, and finally tires are all in peril when used with even 10% safety margin. Ask anyone who hits a pothole at 60 mph with a trailer that has D rated tires that weighs in at over 12,000 lbs. All components used fail prematurily when used at design limits. Tires fail first simply because they degrade over time and require matainance. They require checking pressure before use and airing up if low. The #1 cause of tire failure even in cars and light trucks is underinflation.

This problem is with the trailer manufacturers who knowingly put tires on a rig that is probably unsafe the day it rolls off the assembly line and it also is our fault for not forcing manufacturers to design safer running gears on rigs we ultimately buy and are required to maintain.
-Paul R. Haller-

[Tireman9]

Originally Posted by Paul R. Haller

I have had many 5er trailers... some have had tire issues. My experience has told me that ST tires no matter how good they look on paper, just don't last beyond about 2-3 years. I have also gone to load range G tires to prevent tire issues. In my opinion it's the trailer manufacturers that need to have their feet held to the fire here. They are the ones who put load range D tires ion a trailer that weighs in at 12,000 lbs saying that 20 % of the weight is on the truck, leaving 0 safety margin for tires even new.This is dangerous and they play this game because we as consumers allow it.

Vote with your pocket book and do not buy trailers whos running gear is rated lower then the total weight of the trailer! Brakes, bearings, axles, springs, and finally tires are all in peril when used with even 10% safety margin. Ask anyone who hits a pothole at 60 mph with a trailer that has D rated tires that weighs in at over 12,000 lbs. All components used fail prematurily when used at design limits. Tires fail first simply because they degrade over time and require matainance. They require checking pressure before use and airing up if low. The #1 cause of tire failure even in cars and light trucks is underinflation.

This problem is with the trailer manufacturers who knowingly put tires on a rig that is probably unsafe the day it rolls off the assembly line and it also is our fault for not forcing manufacturers to design safer running gears on rigs we ultimately buy and are required to maintain.
-Paul R. Haller-

Paul, Spot on comment. I wonder what would happen if you were to collect information on the total weight of "stuff" people put in their RV, add thatto the weight of water and fuel and then demand a 10% margin on their axles, springs and tires before they buy.

I also wonder what the answer would be if you were to ask for a 2 year or 3 year bumper to bumper 100% warrantee of the RV. I would assume there would be a cost but if they are not willing to offer such a warranty at any price, then I would consider that proof that they know they have designed and manufactured a unit that is probably going to fail and cost you the consumer lots of money. Note this is not some "Extended" Warranty with lots of exclusions but a full B2B warranty as is now standard on cars.

My Class-C has a 3 year B2B on the chassis so I know that at least those parts are covered. I just have to budget for a few hundred dollars average for parts failure each year for the stuff in the coach.

[Ray,IN]

Paul, that is one item the owner of A&R truck stated. Tires and suspension should have a 20% safety factor for reliability.

[Dave&Julie85]

Just heard from a friend of ours they suffer damage to thier camper. He stated the tread on the tire came off and caused damage to the subfloor and wiring inside the camper. He said it was still holding air when they got to they got to the camp site. I have seen this on retreads but never on a non-retreaded tire. I asked him how old the tires were and he said they were only 5 years old. I still have tires on mine that are going on 10 years old. I going to replace them next year for sure.

[Tireman9]

Originally Posted by Dave&Julie85

Just heard from a friend of ours they suffer damage to thier camper. He stated the tread on the tire came off and caused damage to the subfloor and wiring inside the camper. He said it was still holding air when they got to they got to the camp site. I have seen this on retreads but never on a non-retreaded tire. I asked him how old the tires were and he said they were only 5 years old. I still have tires on mine that are going on 10 years old. I going to replace them next year for sure.

Sorry to hear about your friend's problems. Does he know the real loads on each tire so he can be sure he has been running the correct minimum inflation? Does he check the inflation before leaving the campground each day?
If thetires were radial it is possible for the rubber bonds below the belt to suffer premature aging due to high temperature operation.

Does he know if his tire gauge is reasonably accurate?
FyI at the Gypsy Journal Rally Sept 3 in Elkhart I tested 22 gauges. Most were accurate to +/- 3psi or less but one read +15 and one -10.
This 10% "failure" rate is similar to what I saw last year when I tested about 30 gauges and had four that were more than 10 psi wrong.

[ralper]

Tireman9,

I went from 16" G rated to 17.5" J rated tires. My 5th weighs 15,000 # and is rated to 17,500# GVW. Yes I purchased both rims and tires. After two blowouts in a year with the 4 year old G rated tires, @ aprox 26,000 miles, I thought it was time for an upgrade.

The G rated would carry 15,000 # @ 110 PSI. The J rated will carry 19,000 # @ 120 PSI and is a truely heavy weight tire.

[John]

Thinking of the cost. I have just spent right at $1254 for four new G614s after losing one at 4 years and not many miles. I believe I might have been almost half way there to upgrade to 17.5". Would some of you that have upgradded please post your approximate cost? I see at one store mentioned the wheel is priced at $223. What about tire, mounting, balancing and shipping? Can't seem to get much info locally.

[wingnut60]

www.trailertiresandwheels.com will answer all your questions about a changeout. At $1254, you certainly were near the halfway point to getting a set of 4 17.5" wheels and tires sent to your doorstep. Putting them on the trailer would be up to you, but an easy task anywhere. My cost in 2008 from them was under $2000 for all 4--mounted/balanced--but I picked them up at their shop as I was on a solo trip near their town. I got the recommended wheel and Michelin ATX 'J' tires, took them home and put them on myself. Got $225 for the GY tires and rusty steel wheels on Craigslist. 3 years and maybe 20000 miles later, I cannot even tell the tread is worn and no flats. The swap is a simple one, just need the lug bolt pattern and lug size (9/16" or 5/8"). The 17.5" wheel/tire was almost the exact diameter of the 16" GY 614 setup and the size--215/75 is narrower than the 614.
My Mobile Suites (bought used) was mfg'd with ONLY 185lbs cargo capacity when 100gal water capacity was figured in--the upgrade on tires/wheels was a HUGE confidence-builder and stress-reliever for travels in hot TX/AZ summers. I also added TST pressure/temperature monitors this summer and that has also added to the confidence of traveling without a major tire disaster. I now have 19920 lbs load capacity on my trailer that weighs 17,040. At this time, I have 12940 on the 14000 axle rating.
I believe that having overkill on tire capacity is a HUGE step in avoiding blowouts on the road.
Joe