Apr-13-2017 02:13 PM
Apr-30-2017 03:55 PM
Apr-26-2017 03:05 PM
Apr-26-2017 01:31 PM
schlep1967 wrote:
On my Dodge Ram 2500 the "Light Load" pressure is 45 lbs in the rear. Those are E rated tires and the door panels recommended pressure. The dealer is telling you what he thinks. Not what he knows.
Apr-26-2017 07:44 AM
Apr-25-2017 01:17 PM
Apr-25-2017 12:37 PM
Apr-25-2017 04:28 AM
Apr-24-2017 12:32 PM
Apr-24-2017 11:50 AM
Do you have a link to this table? Their website looks like you have to pay for any info obtained.
Apr-24-2017 11:45 AM
CapriRacer wrote:
Don,
3 thoughts:
1) Included on my web page is an analysis of the pressure spec. Short version: The vehicle's tire pressure spec did not result in an overloaded tire.
This is from Dr. Govindjee report on page 34. Seems to contradict you statement as to the affect of pressure and heat on a tire.
5.3 Thermal demands
The climate related degradation of properties that was seen in the return
tire survey points to the importance temperature plays in material behavior.
Likewise, aging studies on ideal laboratory specimens show a measurable
effect of thermal and oxidative aging. There are two major contributors to
the temperature of the tire: (1) is the ambient temperature and (2) is the
heat generation from within the tire.
1. Low inflation pressure, highway speeds, and heavy cargo loads all play
a negative role in terms of contributing to thermal aging. When all
three factors are present, the temperature rise in the belt region of the
tire can be as high as 50C over the ambient temperature.
2. When carrying heavy loads and at high speeds, decreased inflation
pressure can substantially increase tire temperature.
2) Firestone's own consultant (Dr. Govindjee) identified the problem in the tire.
I could not find where he said the tire was defective however there were higher failure rates between Firestone's two factories.
5 Conclusions
This study has found no single causative agent for the tire failures. It has
found a number of comparative differences in tire models that are likely
related to the tire failures and these are summarized below. The primary
issue that impedes additional progress is the lack of established criteria for
different types of tire failures. Development of such criteria is only today
becoming scientifically and technologically possible.
The other main point is why were no other vehicles seeing the same failure rates using the same tires that Ford was having with the Explorers? These tires were also being used on the Ford Ranger without any issues. The other thing pointing to low tire pressure and heat is that the vast majority of the tire failures were happen in hot climates.
3) The tire was recalled, but the vehicle wasn't. If the Feds didn't think the tire was the sole problem, why didn't they recall the vehicle?
The vehicles were recalled Ford had to replace those tires not Firestone. The vehicle manufacture is responsible ALL parts installed on their vehicles not the supplier. The total cost to Ford for the recall was over 3 billion dollars.
Barry
Apr-24-2017 10:09 AM
jefffoxsr wrote:Do you have a link to this table? Their website looks like you have to pay for any info obtained.
I called the tire manufacturer for my new tires. They said absolutely you can run under 50 psi in load range E tires. They said to refer to the tire and rim association load and inflation tables which also show load rates for inflation pressures as low as 25 psi for load range E 10 ply tires. I have this table and found it again on the internet to confirm it.
Some tire manufacturers publish documents showing what they determined to be the proper air pressure for their particular tires to meet OEM standards. They use the tire and rim association table as a starting point to make their determination for their specific tires. These are interesting to look at.
Anyway. I am satisfied, based on the above information, that I can safely run lower than 50 psi on my new tires.
Apr-24-2017 08:17 AM
Apr-24-2017 05:38 AM
Apr-23-2017 04:43 PM
CapriRacer wrote:
Perhaps it is time I stepped into this:
First, read my webpage on the Ford / Firestone situation a few years back.
Barry's Tire Tech - The Ford / Firestone Controversy
Summary: The problem was the tire, not Ford's inflation pressure specification.
Second, the pressure listed on the sidewall of a tire is a MAXIMUM - not a recommendation. The tire manufacturer does not know what vehicle a tire is going to go on, so they can not make a universal recommendation that could be printed on the sidewall.
Further, if you ask any tire manufacturer what they recommend for inflation pressure, they will point to the vehicle manufacturer's spec - the one on the doorframe.
From the link wrote:The number one cause of tire blow outs is the tire being run at low pressure causing the tire to over heat and blow out.
Ford insists that Explorers fitted with Goodyear tires have experienced far fewer tread problems than those equipped with Firestones. Firestone retorts that the same tire that shreds on an Explorer holds up just fine on a Ford Ranger. General Motors last week described the safety of the Wilderness AT tires it puts on pickups as "excellent"—although the No. 1 automaker said it was planning to switch to the Bridgestone brand for some of its vehicles this summer. (Bridgestone owns Firestone.)