Radial Tire "Deception" ????

[obbm]

Has anyone heard of radial tire "Deception"? I bought 2 new steer axle tires, Goodyear G661, 245/75R22.5, which were inflated by the installer to 110 psi, the maximum listed on the sidewall.

I called a Goodyear tire dealer who services a lot of class A M/H. He said 110 is way too high. He explained that there is a steel belt around the tire which is about 3" wide. Over inflation and heat generated pressures cause the tire to expand but the steel belt restrains the center part of the tread, allowing the outer edges to expand and then wear out. He called it radial tire "Deception".

We arrived at 95 psi as being the correct pressure.

This is exactly what happened to the two previous tires, they severely wore out both edges of the tread, not due to under inflation.

Any discussion welcome, and thanks for any enlightenment.

obbm

[D Lindy]

First and foremost weigh you coach, then using the tire mfrs inflation chart air you tires up accordingly. Most will add 5 psi over what the chart calls for. How did the 2nd dealer come up with the 95 psi inflation?

[wa8yxm]

Never heard of that however I do know that proper inflation, based on the weight the tire is carrying, is very important for many reasons. If you re read that sidewall you should find it does not say
Maximum Pressure 110 PSI

it says Maximum Load _____ at Maximum Pressure of 110 PSI.

That is important, less than maximum load, you use less than maximum pressure.

[obbm]

D Lindy & wa8xym, thanks for your replies. You are correct on numerous items.

Just before I had the new tires installed, I weighed the wheels. I got LF 3900#, RF 3580#, no passengers.

The new tires are load range G. I weigh 175#. 3900 + 175 = 4075#. The load/psi chart says 90 psi = 4140#, so we added 5 psi to be safe, at 95psi. 95 psi = 4300#, on a single tire.

It says max 4675# at 110 psi, wa8xym, you are correct.

Thanks for discussion,

obbm

[Gary RVRoamer]

Never heard of that term, not can I find it in any tire industry guide that describes tire issue. But its certainly true that the tire will like having its pressure optimized for the load.

I would think that a tire would have to be drastically overinflated to get the sort of edge wear you described. 10-15 psi probably isn't gonna do it on a 100 psi tire. In fact, many experts recommend running 10% above the optimum, to minimize the possibility of ever being a bit too low as temperatures or loads change.

[obbm]

Gary, thanks for your input. The tires wore almost out on each outer edge of both tires, with the three or four grooves in the center of the tread almost 5/16" deep. I would blame severe underinflation, but the tires were at 85# when I checked them, and had only been driven at 85# for about 20 miles, and there was no tapering, about 1 1/4" of the edges were just worn out.

I had the alignment checked in a good shop in Lake Charles, LA, 1700 miles from where we live. I had inflated the tires to 95# for the trip, and experienced no further wear. The tech said they had a lot more life in them, and we drove at least 10,000 miles more, then replaced them because they were 9 years old.

I had never heard of that before, and the tech who did the alignment couldn't explain it, either.

We did fill them at 90# in 50 degree weather, then drove twice from coast to coast and back on Interstate 10 (about 15,000 miles). Maybe they severely overheated and experienced radial tire "Deception". I may never find an answer.

Thanks again,

obbm

[Mr_D]

Originally Posted by obbm

Has anyone heard of radial tire "Deception"? I bought 2 new steer axle tires, Goodyear G661, 245/75R22.5, which were inflated by the installer to 110 psi, the maximum listed on the sidewall.

The pressure on the sidewall of a GoodYear RV tire and many others is not the "Maximum" the tire should ever have (unlike car tires) it is the minimum to support the maximum rated carrying capacity of the tire.

From the Michelin RV Tire Guide:

"If you look at the tire's sidewall, you'll see the maximum load capacity allowed for the size tire and load rating, and the minimum cold air inflation needed to carry the maximum load."

From page 6 of the GoodYear RV Tire and Care Guide:

"How much air is enough?
The proper air inflation for your tires depends on how much your fully loaded RV or trailer weighs. Look at the sidewall of your RV tire and you’ll see the maximum load capacity for the tire size and load rating, as well as the minimum cold air inflation, needed to carry that maximum load."

Inflation Pressure Safety Margin
Toyo Tire does not recommend an “inflate-to-the-load” policy for RV tires. Tires that are inflated to accommodate the vehicle’s actual loads do not have any inflation safety margin. Consequently, even a minor loss of air pressure will cause the tires to be under-inflated and overloaded. Toyo Tire’s policy is to observe (as a minimum) the tire pressure established by the vehicle manufacturer as indicated on the tire information placard. There are multiple reasons why a safety margin
(by inflation) makes sense:
• All tires lose about 1-1.5 PSI per month due to natural permeation of the tire’s internal air pressure through the tire’s rubber membrane.
• In the event of slow air leaks from punctures, an inflation “reserve” may allow detection and repair of the leak prior to reaching a dangerously low inflation level.
• A safety margin is prudent for users who are apathetic regarding tire inflation maintenance.

But then they go ahead and publish a weight/pressure chart allowing lower pressure for RV's!!

From the August 2010 Motorhome Magazine "Tread Carefully" tire article:

The maximum load capacity allowed for the size tire and load rating and the minimum cold air inflation needed to carry that maximum load are located on the tire’s sidewall.

[Hooligan]

I think the term he wanted was deflection, but I have only seen "radial tire deflection" used in relation to underinflation. This allows the tread to deflect or squirm, again causing increased tread wear along the edges....
http://www.nitrogentiremachine.com/p..._inflation.htm

[obbm]

Mr_D,

Thanks you for your input. I agree that charts and instructions are important to tire maintenance.

Have you seen this chart (in PDF format), removed from another thread?:

www.irv2.com/forums/attachment.php?attachmentid=4766&d=1279746963

Thanks again,

obbm

[obbm]

Thanks, Hooligan, when he was searching for a term, maybe that's what he was trying to say.

obbm