Tire Size Question

[Crasher]

Yes, another tire post. A friend has had four tire failures on a recent trip. Tire size is 235X85R16 LRE. To help determine the problem, I had him get the coach weighed. Here are the numbers:

...................................Axle Rating
Front......... 5700#............6,000#
Drive........10,700#..........11,000#
Tag............3,400#............3800#

@80 psi, the steer tires could carry 6,080#
@80 psi, the Drive tires could carry 11,120#
@65 psi, the tag tires could carry 5250#

He sets all of the tires at 80 psi for simplicity. The oldest tire was three years old and the youngest was one year old. I am at a loss for the reason for these failures. He put six new tires on three years ago and has lost four of them in that time. On two the tread started to separate and he felt a vibration and stopped before they went flat. The last one just blew with no warning. I don't want to get a brand discussion going, as some on the forum have had good results with this one. Some consider it a Tier 2 and some a Tier 3.

Does he not have enough safety factor for the weight they are carrying vs their capacity? Would "G" rated tires (3415# @95 psi) be the solution? I'm not sure his steel wheels are rated for 95 psi. Is seems odd that the old 235X80R16 LRE was rated at 3480#, but is no longer available in an LT tire and the 235X85R16 LRE can only carry 3042#.

Solutions???

[dmurdock]

Axle weights help but you really need corner weights as one side could be holding more weight than the other (however getting corner weights is really hard to do).

Simple solution is get higher rated tires..

[twinboat]

What brand tire ?

Does he drive 85 MPH ?

Does he back around sharp turns, stressing the tires ?

Does he hit curbs on turns, beating up the sidewalls ?

[Crasher]

Originally Posted by twinboat

What brand tire ?

Does he drive 85 MPH ?

Does he back around sharp turns, stressing the tires ?

Does he hit curbs on turns, beating up the sidewalls ?

He drives 60-62 mph.

When we have traveled with him, I haven't seen anything other than cautious driving.

[Crasher]

Originally Posted by dmurdock

Axle weights help but you really need corner weights as one side could be holding more weight than the other (however getting corner weights is really hard to do).

Simple solution is get higher rated tires..

Yes, I wanted corner weights, but I'm not there to assist him and my first thought was that maybe there was something obvious with the axle weights.

[greystroke]

Originally Posted by Crasher

Yes, another tire post. A friend has had four tire failures on a recent trip. Tire size is 235X85R16 LRE. To help determine the problem, I had him get the coach weighed. Here are the numbers:

...................................Axle Rating
Front......... 5700#............6,000#
Drive........10,700#..........11,000#
Tag............3,400#............3800#

@80 psi, the steer tires could carry 6,080#
@80 psi, the Drive tires could carry 11,120#
@65 psi, the tag tires could carry 5250#

??

I would not be comfortable with these figures. For similar reasons I increased my tire size to provide greater safety after two blowouts.

[bill06447]

Put four people in the coach and you're right at "redline" I'd say time to put the coach on a diet or larger tires.

On another note tread separation is usually the result of underinflation. I'm wondering if there is a leak in a valve extension or central inflation system?

[Crasher]

Originally Posted by bill06447

Put four people in the coach and you're right at "redline" I'd say time to put the coach on a diet or larger tires.

On another note tread separation is usually the result of underinflation. I'm wondering if there is a leak in a valve extension or central inflation system?

He weighed the coach with his wife and the dog in with the fuel and fresh water tanks full. Also had the coach loaded for a six week trip. Probably would never be heavier than it is now. He has a TPMS and says all are within a pound or two of 80 psi in the morning before starting out. It just doesn't make sense. Need to dig deeper.

Here is an excerpt from a larger Tire Failure article:

Traditionally, the tire industry has attempted to shift the burden for defective tires to the victim in the accident. They assert that tread separations are the result of impact damage or underinflation. In fact, underinflation does not cause tread belt separation in a properly constructed, properly designed tire. However, if a tire has manufacturing or design defects and it is run underinflated, underinflation can accelerate tread belt separation.

[Gary RVRoamer]

With those tires loaded right to their max limits, 24/7/365, I would not expect a long life (7-10 years). And if any of those axles are a bit off-balance (one end heavier than the other), that axle is going to have one tire that is overloaded.

I would say that a bigger tire is needed, or same size with a higher load rating (and consequently higher psi).

[Triker56]

Their is no bigger tire for his 16" E ones.
80 PSI is the max pressure on them.

Only thing he can do is reduce the weight he carries or trade it for one that has 22.5" tires.

Usually weight is heaver on one side then the other. So he could be over on the front or back on one side then what the tires are rated for.

So a diet is required or he also needs a good ERS and always carry a couple of spares(requires reduced weight of other things) with him. Only carry enough fresh water for bathroom flushing and hand washing when traveling.
20 gal should be plenty.

[greystroke]

[QUOTE=Crasher;Traditionally, the tire industry has attempted to shift the burden for defective tires to the victim in the accident. They assert that tread separations are the result of impact damage or underinflation. In fact, underinflation does not cause tread belt separation in a properly constructed, properly designed tire. However, if a tire has manufacturing or design defects and it is run underinflated, underinflation can accelerate tread belt separation.[/QUOTE]

After two blowouts I started paying more attention to my tires. I increased the size and bought a pressure monitoring system. I went to the Tire and Rim Assoc Tables to determine my pressures with some experimentation. When I had my front blowout I was running my pressures high. But traveling cause the pressures to rise significantly and I have no idea what the pressure was when the tire exploded like a bomb, tearing up electrical harnesses and causing a wheel seal to leak. Now I set my cold pressures on rear at 87 and my front at 94 cold. On the road my pressures increase 10-15 psi. Now my tires wear good and my mileage is great (9-12.5).

Get larger tires and adjust pressure IAW Tables.

[Crasher]

I think he is stuck with a 235X85R16 size due to his rim size and the needed spacing for the rear drive axle dual tires. If he can not reduce the weight significantly, he will have to find a G rated tire in that size if his steel wheels will accept 90-95 psi. I've urged him to go back to the scale to see if he can weigh just one size to determine each position weight.

[mccrob]

Had the same problem with my old gas coach. Put 6 tires on had 4 blow outs in less than 5000mi. The problem was I put tires on that had fabric side walls only thing that will live is a tire with steel in the side walls, Michelin or Bridgestone in that size

[Grey Ghost I]

LRE? If that means load range, there is the problem. Put on a much higher load range tire and stop the flats.