tire failure analysis

[Tmoose]

I'm looking for picture chrt of tire failures and causes.

A friend has had several tire failures on his camper trailer over the last few years. Typically involves sudden tread separation and reportedly ocurrs on a portion of a particulary rough highway perpetually under construction so it is grooved and stepped, especially at the steel strips before bridges and overpasses. The failures tear up his camper badly. At least once he noted a bubble at home before it failed. The ruff highway is about an hour into his trip. He is conscientous about not overloading his trailer, and inflating to the trailer manufacturer's spec (50 psi I think). The only thing I think is missing is a manual check of tire pressure and temp so on the trip.

Only one mfr makes the size of tire he needs ( 14 inch something I think). US name strong in trailer and lawnmower tires.

 

[GregLocock]

"At least once he noted a bubble at home before it failed."

Words fail me.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[patprimmer]

The noticed a bubble line blows me away.

If I am hard up for cash, I normally buy second hand tyres for light duty single axle trailers, normally on second hand alloy wheels, as they are cheap, already fitted up and balanced. I do this as tyres normally rot out before they wear out on a trailer. I look for tyres with good fresh sidewalls and no sign of repairs or kerb damage. I look for OEM alloy wheels with tapered seat wheel nuts of a heavy car so the tyres are big and have good load rating. I stay away from low profile performance tyres.

If the loads are going to be high I go for light truck tyres, generally 6 ply rated.

I NEVER EVER use retreads on a trailer as rot rather than tread wear limits life.

I always check pressures and normally run about 40 psi

My extensive experience towing trailers could not contribute to statistics on tyre failure as I never had one.

Regards

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[CapriRacer]

There is a manual put out by the Tire Industry Association, but unless you are a member, and given what you are trying to do, it's way too expensive (about $200 for a non-member)

Besides, tire failure analysis is not something a novice should attempt. It is very difficult to look past all the downstream damage to see the real source of the problem.

So I would suggest the following: First, since you've identified a location where the tires fail, then it's likely that road hazard is the problem. The way around this would be to oversize the tires and use lower inflation pressures - the net effect being the same load capacity.

Second: Just to check to see if overloading or underinflating is the problem - your friend ought to measure his pressure buildup. Measure the tires immediately before starting out, and measure at 15 minute intervals until the pressure no longer increases. He should get about 3 to 5 psi buildup. Any more than 5, and more pressure is called for - which he should immediately take care of. If he exceeds the rating of the tires, he needs larger capacity tires. Just an FYI - trailer manufacturers are really bad about sizing tires. - marginal at best.

I'd also suggest he thoroughly inspect his tires for cuts and bubbles. It doesn't take very long for a cut into a steel belt to turn into a separation - a few hundred miles. I'd suggest and inspection at both ends of the trip and to mark the location of any cuts he finds. A paint stick works great for marking the sidewall.

I would suggest a methodical approach to this problem. Others have noted the way in which the "bubble" was addressed and that speaks volumes. If your friend is tired of tire failures, he's going to have to do some work.

 

[Tmoose]

"At least once he noted a bubble at home before it failed."

Sorry I added to the confusion.
When he noted the bubble he replaced the tire.
All the failures occurred on tires with no known defects, inflated to the trailer manufacturer's specs.
He tried to upgrade to a light truck tire, but there are reportedly fitment or load rating issues that lock him into a particular tire from one mfr.

 

[CapriRacer]

"....He tried to upgrade to a light truck tire, but there are reportedly fitment or load rating issues that lock him into a particular tire from one mfr...."

Nevertheless, try the pressure buildup test. This will tell him if he has an overload problem. If he does, then he can start finding ways to solve it.

 

[patprimmer]

If the tyres on the tow car are not failing, it is at least a combination of road hazards with inadequate tyre rating or poor maintenance.

Light truck tyres can be obtained in quite small sized, as used on some Japanese delivery vans with small dia dual wheels.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[CapriRacer]

Pat,

It might not be common in other parts of the world, but in the US there is a tire sizing standard specifically for trailers called "ST" - Special Trailer. These are in essence passenger car sizes that can use higher inflation pressure, and therefore can carry more load. In a lot of respects they are like LT tires.

The European versions of LT tires ("C" for Commercial) are a more logical way to address this issue, although that can be confusing for a consumer (tire dealers, too!) because the tire size looks identical to a passenger car tire - except for the letter "C".

From the description of the problem, it sounds like Tmoose is talking about one of those - and here's a guess - ST205/75R14.

 

[TheBlacksmith]

Has he ever weighed the trailer? Many times the design or catalog weight is exceeded by a considerable margin by the manufacturer, add a box of crackers and you're at the limit. I'm thinking ST tires also, generally load range C for extra capacity and higher rot resistance as they assume the tires will be setting much more than they're rolling.

 

[RoadTrip]

I'll be quick and to the point.
When I had belt separations on 2 my 2 year old ST225/75R15 tires (I had a tire pressure monitoring system in place) and then one of the other two started loosing air, I started researching the ST tire. Here is what I found:

1. All ST trailer tires were only Speed Rated to 65 MPH, except for one.(this includes the Marathon, anything sold by ST that Carlisle, Maxxis, Denman, Greenball, Kenda (Nankang and Loadstar),TBC, Titan

2. The only ST tire rated for more than 65 MPH was the Cooper Custom Trailer Plus and it has been discontinued.

3. The construction and demolition industry that uses trailers of the general weight range that my travel trailer is gave up on the 15 inch ST tire years ago and went to the 16 inch LT tire of the appropriate weight range. I went to the Goodrich Commercial T/A, LT225/75R16 LRD.

4. There is a Government entity, the National Highway Transportation Safety Administration that looks into tire failures. Had the Explorer owners complained instead of waiting til people started to die, so many would not have died. I have found in the last few months that if complaints are filed with these and investigation will be started. This is the case with the GoodYear Marathon. To file a complaint go to this web site:

http://www-odi.nhtsa.dot.gov/ivoq/index.cfm

after only 10 complaints being filed in rapid succession a "campaign" has been initiated. I urge you, please file a complaint with the NTHSA.

5. These tire failures are not our fault. It’s the fault of these ST tires. They are just not up to the task.

Would I buy a ST tire for a boat trailer that goes around town back and forth to the boat ramp or a utility trailer that does not see interstate? Of course I would. They are cheap and do well in that circumstance.

Road Trip