Hyperinflating tires

[aerohead]

Originally Posted by trikkonceptz

On those statements I have to say that tires do not cause rollovers, drivers do. I do not want to estimate how many millions of miles I have logged driving vehicles of all kinds and towing trailers from small to large. NEVER have I lost control of a vehicle with a blow out. And I have had blow out from disintegrated tires, straight to the rim down to trickles where you here the air leaving one revolution at a time. When a driver panics and gets stupid, stupid things happen. And honestly the only tires I have ever seen physically fail are tractor trailer recaps. They get hot, usually from under inflation and over loading and the glue that holds the caps on fails and lets go, causing either a blow out with launches tread, or tread loss without a blow out.

Unless tires are manufactured with defects, like the Firestone recal, a tire won't fail, it will blow out due to a puncture, but tires do not fail. Obviously some may think I am wrong, but site situations when tires can fail where their maintenance and or abuse is not a factor.

I'm working through the posts.Since this is a safety related topic I'm trying to stay connected.I believe there is much to your comment about puncture,or at least loss of pressure,as I believe it is directly associated with the rollover deaths and spinal chord injuries suffered in the Ford Explorers with Bridgestone tires.The SUVs were heavy,they might be operating during peak summer temps,and often the tires were underinflated.Tread and sidewall deformations caused rapid heat buildup,which eventually exceeded the vulcanization temperatures which determine bond integrity within the tire,ultimately leading to separation,blowout,impact with road barriers(designed for passenger cars with lower C.G.s) which literally" tripped"the SUVs,toppling them over.

[aerohead]

Originally Posted by mattW

My question is what is the relationship between contact patch and traction... in physics we are taught that the contact patch is basically irrelevant to friction because as the area increases the force per unit area decreases. Here my a post about it in a different thread:


Is there any reason why what I said isn't true? I don't know anything from my own testing, that was just repeating what I learnt at University.

I think the premise for overinflation,is that it would reduce tirewall cyclic deflection and deformations at the tread face which effect RR,and which would perhaps forestall standing wave.There must be something to higher pressures,as LLR concept tires all have elevated pressures,and are designed "AROUND" this parameter.-------------------------------the thing about contact patch as associated with traction may not hold up,as Don Schroeder of CAR and DRIVER conducted tire tests on a Corvette,at Chrysler Proving Grounds 300-foot skidpad,and found that when one of the very wide front tires was replaced with the very skinny compact spare,the car performed to essentially the same maximum G-force,in spite of the compromised contact patch.The skinny tire did remarkably effect turning response.

[aerohead]

Originally Posted by RH77

OK, here's a question:

During testing, how high has a tire's pressure limit been tested?

Let's say we put 60 psi/warm in a 44 psi-rated passenger tire. In a controlled lab facility, has anyone witnessed a tire failure? How about 60, 80, 100? What is the maximum average pressure a "gas station pump" can inflate a tire?

So far, a valve stem failure and potential road debris can likely cause an overinflated tire to fail. Further questioning:

What is the statistical different in overinflation vs. recommended for road debris failure?

A valve-stem failure would not likely cause a catastrophic blow-out. The pressure would be released a ordered fashion, as not to heat the tire to a catastrophic blow-out, but rather to a uninflated condition -- which is very noticeable to the driver.

I had a catastrophic blow-out on a brand-new '96 Civic. Highway speeds at 70 mph. The tire disintegrated into 2 separate rings with sidewall separation. Stabilizing the vehicle was a challenge and nearly resulted in a loss of control. Tire experts examined the carcass and blamed a weak manufacturing process. Dunlop's lawyer argued underinflation. Long story short, I was screwed out of a brand new tire and had to buy a new one out of pocket. Good luck getting any "Warranty" replacements on failures.

I vowed never to buy a Dunlop product again -- and recommend the same for any reader.

The questions in the first portion of this thread are requested for consideration. Otherwise....

I propose a collective experiment.

If there is interest, I plan to draft an experiment using the Scientific Method. Those who utilize overinflation could volunteer to offer data based on pressure, number of miles driven, tread wear (inside, middle, outside -- and last vehicle alignment), pictures of the tire, and reports of any failures. A long-term extension study could be offered to track the longevity of these pressure. I propose weekly check-ins with consistent testing of pressures (warm) and ambient temps. A control group of normal-pressure participants would be requested.

Statistical analyses could generate some conclusion on this subset of data. Although it's not a final conclusion, a basis for additional, repeatable testing could be derived.

RH77

At Bonneville,and during some of the Mileage Marathons with the unlimited classcars,tires have been routinely inflated to up to 200-psi.At Bonneville,the old Mickey Thompson speedway slicks are "hyperinflated" to prevent Standing-Wave which melted the tires right off Malcolm Cambell'
s Bluebird racer( you don't want to crash at 350-mph ). For the Mileage Marathon's,the hyperinflation would prevent any deformation of the tire,and reduce the contact patch to the bare minimum in efforts to reduce RR.NOTE all these cars run on a closed course,with Emergency Medical Technicians and ambulances(air ambulance at Wendover) and must pass a rigorous safety inspection before allowed access to the track( see World's Fastest Indian).

[aerohead]

Metal valve stems are great,cheap,available,and very doable at any tire store.Metal screw on caps with seals act as second line of defense in case of Schrader valve failure.No brittle failures!

[aerohead]

I think there should be a context for this graph.It's a great graph,but its not what it says that bothers me.

[aerohead]

Originally Posted by whitevette

"...seems to be..."? How concrete is this? "Over-inflating the tires beyond recommended pressures ... no measurable improvement in MPG (sic)." I do not know what planet you live on, sir ... but in my neck of the woods, your words carry no weight. Any IMSA person ( myself included) knows to the contrary.
Tire science is surrounded by half-truths and legend. If one but "follows the money", they will clearly see the tire industry is fiercely competitive...and the gaining of sales contracts is the life-blood of this industry. So ... given these parameters, can we safely say the industry does not want to endorse the raising of cold pressures ... which will increase the life of the tire ( as well as improve handling and traction)? After all, replacement tires fuel the industry.
And who is gambling with their life for the sake of a gallon of fuel? I thought you just stated there was no measurable improvement in MPG? Now you're talking "a voilent end-swapper" if you change the pressures. This is fear tactics....
The truth is : traction is improved markedly with a small (reasonable) increase in tire pressure, firming the foundation carcass rubber ( reducing tread squirm). Reducing tread squirm cools the rubber and lengthens tread life.
Cars which "break loose" at the front first (understeer) are more forgiving...mushy... and cars which "break loose" at the rear ( oversteer) need to be "steered" with the counter-steer / throttle / hand brake. With the majority of drivers on the road being virtual idiots under either condition...does it really matter about tire pressure bias? "They" lock 'em & hang on!
I'll stop now. Have a nice day.... -Ted Hart / ex-IMSA / Z twist, S twist

The data is from a comprehensive tire performance test article and report on the p-metric tires,published by the technical editors of CAR and DRIVER magazine(whom all possess at least a bachelors degree in mechanical enginerring,if not higher).Their information is from the tire manufacturers,the goverment agencies involved.The most remarkable aspect of the article has to deal with the TPC of which I would like to pose directly to our tire expert.I will ferret out the information and post it.I think I'm at page 8 of this thread and its hard to keep up with all the allegory and mis-information I'm afraid will end up killing some of our members.

[aerohead]

Originally Posted by CapriRacer

I'm starting a discussion thread here - and I'm hoping to move a discussion that got started when I introduced myself:

http://www.ecomodder.com/forum/showt...ires-2522.html

So hopefully this will be a bit more visible and a bit more "on topic".

First, let's define some terms:

Underinflation: Using less inflation pressure than is listed on the vehicle placard (assuming the placard tire size is being used.)

Overinflation: Using more inflation pressure than is listed on the vehicle placard (assuming the placard tire size is being used.)

Hyperinflation: Using more inflation pressure than the maximum listed on the tire sidewall.

Vehicle placard: The sticker on the vehicle that lists the original tire size and the proper inflation pressure for that size.

Agree?

Any other terms we need to define?

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.

[Johnny Mullet]

I have been staying away from this thread for my own reasons. I have been in the tire business for many years. All I have to say is this.................

I am safer in my car with tires inflated to MAX than that person with 4 under-inflated tires.

I see it all the time! Literally 80% of all cars on the road have under-inflated tires due to lack of maintenance. Those are the people who need help, not us!

Remember the Firestone/Ford Explorer recall? The label on the door called for 28 PSI in these tires. Like most lazy people, the tires are never checked and eventually the tire gets so under-inflated they come apart. The new labels offered in the recall program amended the tire inflation numbers.

Look at the current Ford Taurus door label. They want you to run 30 or 32 PSI in these crappy Continental tires on a full sized car! I wonder why so many Taurus owners complain of tire wear issues? If you own a Taurus from like 2000 and up or know someone who does, just take a look at how squat the front tires look with 30 PSI in them.

I do not believe in adding more air than the tire manufacturer stamps on the sidewall, but you are still safer with over-inflated tires than you are with under-inflated tires. The majority of all the people on this forum at least have the ambition to check their tires on a regular basis no matter what the pressure is set to.

[CapriRacer]

Originally Posted by aerohead

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.

ALL vehicle manufacturers - GM included - specify practically everything about the tires that get supplied to their vehicles. Individually, vehicle manufacturers buy so many tires that the tire manufacturers are more or less powerless to argue the point.

In practically all cases, the tires supplied to the vehicle assembly plants are different than tires that are designed for the replacement market.

Vehicle manufacturers have a select list of qualified tire suppliers (and other parts suppliers). The process to qualify a tire supplier (or any supplier of parts) is arduous, but the benefit to a tire supplier (or any other part supplier) is a fairly simplified supply chain - a steady shipment of a large quantity of parts going to a single drop off point for a long period of time - typically 3 years.

What usually happens is about 2 years before the start of production, there is a letter issued to each of the qualified tire suppliers specifying what the performance characteristics the tire is supposed to have. The letter outlines the tests that have to be performed and the performance level to be achieved. This includes rolling resistance, force and moment, traction (dry, wet, and snow), ride quality, handling, etc., and wear. The problem is that the inexpensive tests are run first - lab test (rolling resistance, force and moment, etc.) - followed by increasingly more expensive tests - traction, ride, handling, etc. Ride and handling test are performed by the vehicle manufacturer, although the tire manufacturers do a screening series of ride and handling to not only select the best tire candidates, but also to gauge the correlation with the vehicle manufacturer's ride engineer.

The last tests performed are wear tests as they are the most expensive. It is not uncommon for wear problems to surface. Sometimes this means starting over, but sometimes tires are pronounced ready for production with known wear issues. Sometimes the problem is in the vehicle and while tire testing is expensive, vehicle suspension redesign is many times more expensive.

In the case of General Motors, they have a Tire Performance Criteria, which delineates the performance of a particular tire. They require the TPC number to be branded on the sidewall to indicate the tire meets this criteria. Ford, BMW, VW, Mercedes also require indicators on the sidewall and each vehicle manufacturer's requirement is different. For example, BMW requires a 5 pointed star. I am sure other vehicle manufacturers have sidewall marking requirements, but I don't know them all.

It is not uncommon for what appears to be identical tires to be supplied to different vehicle manufacturers - and, of course, the tires are different - sometimes easy to see (such as a tread pattern difference) and sometimes not (say, tread compound)

For practical purposes, all vehicle manufacturers require tires with lower rolling resistance than is supplied to the replacement market. The classic triangle is rolling resistance / treadwear / traction (especially wet traction) Improvements in rolling resistance come at the sacrifice of one of these properties (sometimes both). That is why you will find many complaints about OE tires for treadwear and / or traction.

So, no, GM's TPC system is not holding back low RR tires. In fact the opposite is true. Low RR tires ARE supplied to the virtually all vehicle manufacturers but there are many complaints from consumers.

However, the average consumer doesn't connect fuel economy to tires. Most consumers demand long wearing tires - and since adequate traction is a given, that means high RR for replacement market tires. The exception here is high performance and ultra high performance tires. In these cases, treadwear is sacrificed to get traction.

BTW, OE tires do not have a treadwear warranty (and by that I mean the tires that actually come on the vehicle - not the same ones sold out of a tire dealership). The lone exception is GM, where they have a 3 year, 36,000 mile warranty on tires (with a couple of exceptions). However, this is a GM warranty not a tire manufacturer warranty. GM credits the vehicle dealer for tires that wearout prematurely, not the tire manufacturer. This is a fact not well known to GM dealers and it creates a lot of confusion.


Bottonline: If you are unhappy with the performance of the tires that came new on your vehicle, tell that to the vehicle manufacturer, not the tire manufacturer. The vehicle manufacturer is the one who specified the performance, who selected the tires, who knew how they would perform, and they are the ones who would have to change the specs to get the desired performance.

[aerohead]

Originally Posted by CapriRacer

ALL vehicle manufacturers - GM included - specify practically everything about the tires that get supplied to their vehicles. Individually, vehicle manufacturers buy so many tires that the tire manufacturers are more or less powerless to argue the point.

In practically all cases, the tires supplied to the vehicle assembly plants are different than tires that are designed for the replacement market.

Vehicle manufacturers have a select list of qualified tire suppliers (and other parts suppliers). The process to qualify a tire supplier (or any supplier of parts) is arduous, but the benefit to a tire supplier (or any other part supplier) is a fairly simplified supply chain - a steady shipment of a large quantity of parts going to a single drop off point for a long period of time - typically 3 years.

What usually happens is about 2 years before the start of production, there is a letter issued to each of the qualified tire suppliers specifying what the performance characteristics the tire is supposed to have. The letter outlines the tests that have to be performed and the performance level to be achieved. This includes rolling resistance, force and moment, traction (dry, wet, and snow), ride quality, handling, etc., and wear. The problem is that the inexpensive tests are run first - lab test (rolling resistance, force and moment, etc.) - followed by increasingly more expensive tests - traction, ride, handling, etc. Ride and handling test are performed by the vehicle manufacturer, although the tire manufacturers do a screening series of ride and handling to not only select the best tire candidates, but also to gauge the correlation with the vehicle manufacturer's ride engineer.

The last tests performed are wear tests as they are the most expensive. It is not uncommon for wear problems to surface. Sometimes this means starting over, but sometimes tires are pronounced ready for production with known wear issues. Sometimes the problem is in the vehicle and while tire testing is expensive, vehicle suspension redesign is many times more expensive.

In the case of General Motors, they have a Tire Performance Criteria, which delineates the performance of a particular tire. They require the TPC number to be branded on the sidewall to indicate the tire meets this criteria. Ford, BMW, VW, Mercedes also require indicators on the sidewall and each vehicle manufacturer's requirement is different. For example, BMW requires a 5 pointed star. I am sure other vehicle manufacturers have sidewall marking requirements, but I don't know them all.

It is not uncommon for what appears to be identical tires to be supplied to different vehicle manufacturers - and, of course, the tires are different - sometimes easy to see (such as a tread pattern difference) and sometimes not (say, tread compound)

For practical purposes, all vehicle manufacturers require tires with lower rolling resistance than is supplied to the replacement market. The classic triangle is rolling resistance / treadwear / traction (especially wet traction) Improvements in rolling resistance come at the sacrifice of one of these properties (sometimes both). That is why you will find many complaints about OE tires for treadwear and / or traction.

So, no, GM's TPC system is not holding back low RR tires. In fact the opposite is true. Low RR tires ARE supplied to the virtually all vehicle manufacturers but there are many complaints from consumers.

However, the average consumer doesn't connect fuel economy to tires. Most consumers demand long wearing tires - and since adequate traction is a given, that means high RR for replacement market tires. The exception here is high performance and ultra high performance tires. In these cases, treadwear is sacrificed to get traction.

BTW, OE tires do not have a treadwear warranty (and by that I mean the tires that actually come on the vehicle - not the same ones sold out of a tire dealership). The lone exception is GM, where they have a 3 year, 36,000 mile warranty on tires (with a couple of exceptions). However, this is a GM warranty not a tire manufacturer warranty. GM credits the vehicle dealer for tires that wearout prematurely, not the tire manufacturer. This is a fact not well known to GM dealers and it creates a lot of confusion.


Bottonline: If you are unhappy with the performance of the tires that came new on your vehicle, tell that to the vehicle manufacturer, not the tire manufacturer. The vehicle manufacturer is the one who specified the performance, who selected the tires, who knew how they would perform, and they are the ones who would have to change the specs to get the desired performance.

CapriRacer,thank you very much for your comprehensive "filling in the blanks"!I would like to impose upon you with one additional question,and I'll leave you alone.------------------------ Years ago a certain concept car was revealed,which was credited with 80-mpg potential.The car's two main attributes were never before offered aerodynamic efficiency,and very LRR tires.In the press kit,much was said about the tires and their remarkably low rolling resistance.When I contacted the tire maker,who manufactured the concept tire,and asked if it would be going into production,and would be available in the aftermarket,they thanked me for my interest and explained that the tire design belonged to the carmaker,and they would have the answers I seeked.------------------------ Upon writing to the carmaker,complementing them on their accomplishment,and what a benefit such a technology would be to so many aspects of the American economy and environment,I inquired as to whether they would consider a licensing agreement to allow tire makers to manufacture the LRR tires.The tires offered a 17% improvement in MPG.------------------------------ I received a polite letter from the legal affairs department of the corporation,thanking me for my interest in the tire,and after explaining how many parameters must be balanced,regarding tire selection,at that time,the corporation was not interested in a licensing agreement.---------------------------- In the meantime,the same corporation has subsequently developed another tire which offers over a 26% improvement in MPG.---------------------- As an ecomodder,you might imagine the frustration that might accompany anyone exposed to such a technological coup,realizing they may never have access to such cutting-edge technology.------------------------ Would you hold out any hope that we might see the commercial exploitation of such tire technology within our lifetimes? It seems like the time is right for such things,more so than at any other time. Please comment if you can.Thanks!