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Old 03-01-2020, 09:08 AM   #261 (permalink)
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Thanks capriracer for the reply. I seen this article before but now I'm realizing that even though the footprint with lower pressure may be bigger it may not be any better. I once had a pickup with large tires and you could feel the flotation effect on dirt roads. I think I will stick to placard pressure.

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Old 04-08-2020, 03:19 PM   #262 (permalink)
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How far can you go? And what will happen?

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Old 04-08-2020, 08:51 PM   #263 (permalink)
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Quote:
Originally Posted by aerohead View Post
CapriRacer,I appologise for the digression,however you appear to be the only "insider" we have into the dark world of automotive tire manufacturing.I would like you to address something if you will,concerning the Tire Performance Criteria,published by General Motors Corporation in the 1980s,which essentially transfered tire design away from tire makers and put it in the lap of GM.I'm given to understand that,as the largest automaker in the United States,and controlling the largest share of new car O.E.M. tire ourchases,that GM essentially transferred authority away from tire manufacturers and specified how tires would be constructed from there on out.Since Ford Motor and Chrysler were minority customers,they were forced to go along with whatever GM decided.The issue has significance to ecomodders desiring certain LRR technology,as tire makers are not permitted to manufacture certain proven LRR tires,as they were not developed by the tire companies,but rather by GM,and cannot produce said tires without express permission from GM.
the standard PSI is 38PSI for GM for passenger cars


I was talking to a so called mechanic (one that claimed to be) he said he uses 29PSI and that air expansion will make it higher which is true but why risk a blow out when the side wall fails because it's under inflated..

that is what ford said to use 29PSI shortly after they had tires failing left and right..


if you have it at 40-44PSI the max side wall there is no increase or heating of the tire or heat cycling the tire.. after drive for an hour at 40PSI the tire is still cold to the touch PSI stayed the same


with the tires at 32psi the PSI increased to 36PSI from internal heat expansion
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Old 04-09-2020, 08:40 AM   #264 (permalink)
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Quote:
Originally Posted by Tahoe_Hybrid View Post
the standard PSI is 38PSI for GM for passenger cars


I was talking to a so called mechanic (one that claimed to be) he said he uses 29PSI and that air expansion will make it higher which is true but why risk a blow out when the side wall fails because it's under inflated..

that is what ford said to use 29PSI shortly after they had tires failing left and right..


if you have it at 40-44PSI the max side wall there is no increase or heating of the tire or heat cycling the tire.. after drive for an hour at 40PSI the tire is still cold to the touch PSI stayed the same


with the tires at 32psi the PSI increased to 36PSI from internal heat expansion
Sorry, but most of this post is incorrect.

If I look at Tire Guides - a publication that summarizes the tire placard information for easy reference - GM trucks, vans, and SUV's use 35 psi for P metric tires (when they use those). There are a few exceptions.

I was going to say that GM cars tend to use 30 psi, but a quick perusal of the latest Tire Guides says that that is no longer true - that the recent tire pressure specifications are all over the ball park (range 30 to 36 psi).

The post has an indirect reference to the Ford/Firestone situation some 20 years ago - and 1) The failure was NOT in the sidewall. It was a "Belt leaving Belt Separation" (commonly called a tread separation) and 2) The cause was a combination of the tire design, and the manufacturing, not the inflation pressure. I go into detail here: Barry's Tire Tech

There also appears to be a misconception by the mechanic that the max pressure is close to the burst pressure of the tire. Tire burst pressures are on the order of 2 to 4 times what the max on the tire says.

Lastly, it was stated that high inflation pressures do not generate pressure buildup - ah .. not exactly.

There is pressure buildup any time a tire is operated. The question is how much.

Normal city street driving doesn't generate much (1 or 2 psi), while freeway driving generates more (up to 3 psi). Obviously using a higher than placard pressure would reduce the amount, but it is not zero.

Most pencil style tire pressure gauges measure in 1 psi increments, so 1/2 psi build up would be undetectable by those.

Hope this helps clear things up.
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Old 04-10-2020, 01:41 AM   #265 (permalink)
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Quote:
Originally Posted by CapriRacer View Post
Sorry, but most of this post is incorrect.

If I look at Tire Guides - a publication that summarizes the tire placard information for easy reference - GM trucks, vans, and SUV's use 35 psi for P metric tires (when they use those). There are a few exceptions.

I was going to say that GM cars tend to use 30 psi, but a quick perusal of the latest Tire Guides says that that is no longer true - that the recent tire pressure specifications are all over the ball park (range 30 to 36 psi).

The post has an indirect reference to the Ford/Firestone situation some 20 years ago - and 1) The failure was NOT in the sidewall. It was a "Belt leaving Belt Separation" (commonly called a tread separation) and 2) The cause was a combination of the tire design, and the manufacturing, not the inflation pressure. I go into detail here: Barry's Tire Tech

There also appears to be a misconception by the mechanic that the max pressure is close to the burst pressure of the tire. Tire burst pressures are on the order of 2 to 4 times what the max on the tire says.

Lastly, it was stated that high inflation pressures do not generate pressure buildup - ah ….. not exactly.

There is pressure buildup any time a tire is operated. The question is how much.

Normal city street driving doesn't generate much (1 or 2 psi), while freeway driving generates more (up to 3 psi). Obviously using a higher than placard pressure would reduce the amount, but it is not zero.

Most pencil style tire pressure gauges measure in 1 psi increments, so 1/2 psi build up would be undetectable by those.

Hope this helps clear things up.
officially shown on the sticker on the driver side door 2018 model


i use digital ones they have 0.5psi increments


ford explorer tires blowout google it
was more at the side wall rather then the tread it self

the tread and sidewall failed simultaneously


if the tread left the tire it might still be drive able to come to a stop but a lot of noise
as seen here
i'm sure if you heard that noise you would be slowing down, notice when the tread separates it does not go flat instantly



a side wall blow out goes flat instantly (i personally seen it happen to a pickup truck at 75MPH) the pickup truck was in the next lane over







normally when i think of the tread leaving the tire I'm thinking of the retreaded 18wheeler tires



i dealt with tread separation Firestone tire (flat hard spot i might be able to dig up a photo) and bridgestone tire


here is a photo of tread separation on my bridgestone tire you can see the tire is warped that is because the tread is coming apart..
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Old 04-10-2020, 08:37 AM   #266 (permalink)
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Quote:
Originally Posted by Tahoe_Hybrid View Post
officially shown on the sticker on the driver side door 2018 model
i use digital ones they have 0.5psi increments
ford explorer tires blowout google it
was more at the side wall rather then the tread it self
the tread and sidewall failed simultaneously
if the tread left the tire it might still be drive able to come to a stop but a lot of noise
as seen here
i'm sure if you heard that noise you would be slowing down, notice when the tread separates it does not go flat instantly

a side wall blow out goes flat instantly (i personally seen it happen to a pickup truck at 75MPH) the pickup truck was in the next lane over
normally when i think of the tread leaving the tire I'm thinking of the retreaded 18wheeler tires
i dealt with tread separation Firestone tire (flat hard spot i might be able to dig up a photo) and bridgestone tire
here is a photo of tread separation on my bridgestone tire you can see the tire is warped that is because the tread is coming apart..
First, I can tell you don't have access to Tire Guides - the publication that lists all the placard information for all vehicles sold in the US - because if you did, you would have pointed out that Tire Guides lists all versions of Tahoes as listing 35 psi. You seem to be quoting the placard from a single model from memory - and apparently incorrectly. (I'll concede that Tire Guides might be wrong because they don't list any hybrid Tahoes - but that doesn't explain their other information.)

Further a Tahoe is an SUV, not a car.

And I'll cut to the chase: I've examined 1000's of tread separations - it was my job - so I know what they look like - including the infamous Firestone ATX. Tread separations do NOT involve the sidewall.

Take a closer look at the video you provided. The sidewall doesn't fail - the tire is still holding air. All that debris is the tread and the top belt - the sidewall is still intact. (And for technical purposes, the sidewall starts where the tread ends - and that's about 1" from the shoulder point, an area we tire engineers call the buttress.

Sorry, I stand by what I wrote.
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Old 04-10-2020, 08:27 PM   #267 (permalink)
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it does not matter tire PSI will increase overtime to improve MPG as well as other changes such as being lighter weight as well..


they all ready did this to brake rotors by making them lighter weight minimal thickness.. they compensated by using thicker pads.
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Old 04-10-2020, 09:11 PM   #268 (permalink)
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Old 04-12-2020, 07:33 PM   #269 (permalink)
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Quote:
Originally Posted by CapriRacer View Post
First, I can tell you don't have access to Tire Guides - the publication that lists all the placard information for all vehicles sold in the US - because if you did, you would have pointed out that Tire Guides lists all versions of Tahoes as listing 35 psi. You seem to be quoting the placard from a single model from memory - and apparently incorrectly. (I'll concede that Tire Guides might be wrong because they don't list any hybrid Tahoes - but that doesn't explain their other information.)

Further a Tahoe is an SUV, not a car.

And I'll cut to the chase: I've examined 1000's of tread separations - it was my job - so I know what they look like - including the infamous Firestone ATX. Tread separations do NOT involve the sidewall.

Take a closer look at the video you provided. The sidewall doesn't fail - the tire is still holding air. All that debris is the tread and the top belt - the sidewall is still intact. (And for technical purposes, the sidewall starts where the tread ends - and that's about 1" from the shoulder point, an area we tire engineers call the buttress.

Sorry, I stand by what I wrote.
there is no restriction of the word car model t was 67 inches tall which is the height of small suvs

it's not a truck it's a car on a truck chassis, a truck refers to a bed in the back.. it's one of the reason I get to have a hitched ball permanently affixed to my car. and at the same time not require a commercial plate on it..


hitched ball permanently affixed to a car is illegal, but since i have a truck chassis it's not.

Last edited by Tahoe_Hybrid; 04-12-2020 at 07:39 PM..
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Old 04-14-2020, 12:10 PM   #270 (permalink)
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Quote:
Originally Posted by Tahoe_Hybrid View Post
there is no restriction of the word car model t was 67 inches tall which is the height of small suvs

it's not a truck it's a car on a truck chassis, a truck refers to a bed in the back.. it's one of the reason I get to have a hitched ball permanently affixed to my car. and at the same time not require a commercial plate on it..


hitched ball permanently affixed to a car is illegal, but since i have a truck chassis it's not.
As far as the US government is concerned, it's a light truck. It follows truck emissions standards and is taxed like one.

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