Incorrect Information re: Tire Pressure in Efficiency Mods

[Frank Lee]

I bet the Michelin econo race tires are...

[Arragonis]

Only the dry weather ones, maybe.

[larrybuck]

Everybody should be safe w 5-7psi over sidewall #'s Remember, the figure is LAWYER'S TALK! They are not the IRS! They love to sell tires, and the Veh. Manu. is going to pick a psi for a comfortable and non lawsuit ride! 41 psi works great for my CRX. You'll never find a cheaper or easier mod. Above 5-7 over; I could picture more strut wear... use balance! Question: We all know that an older tire gets harder...not the hot tip for drag/roadracing...but; would a harder tire that's not going to be pushed to lets say 7/10ths of its remaining grip... would that firmness compliment some extra psi for even more mpg.'s in other words... would that harder tire wear down slower than a newer tire? I understand motorcycle bumping up uncomfortable for some... stay in your comfort zone... but if you are hypermiling; you won't be that fast to worry about any difference!

[marinpa]

Originally Posted by CapriRacer

I think I missed the post about the bursting pressure when I posted

- BUT -



I think Sularus was looking for something more definitive. In your post, the one link is an article that doesn't mention burst pressure and the other is a link for a forum basically stating it, but no reference to where that information came from.

Sorry CR but I fail to see the parallel between steel fatigue and tire (rubber)

Can you please tell us how the fatigue between the two of them relate?

[marinpa]

Originally Posted by larrybuck

Everybody should be safe w 5-7psi over sidewall #'s Remember, the figure is LAWYER'S TALK! They are not the IRS! They love to sell tires, and the Veh. Manu. is going to pick a psi for a comfortable and non lawsuit ride! 41 psi works great for my CRX. You'll never find a cheaper or easier mod. Above 5-7 over; I could picture more strut wear... use balance! Question: We all know that an older tire gets harder...not the hot tip for drag/roadracing...but; would a harder tire that's not going to be pushed to lets say 7/10ths of its remaining grip... would that firmness compliment some extra psi for even more mpg.'s in other words... would that harder tire wear down slower than a newer tire? I understand motorcycle bumping up uncomfortable for some... stay in your comfort zone... but if you are hypermiling; you won't be that fast to worry about any difference!

I am using 10 PSI over the sidewall max. technique for more than 8 years, with over 200,000 km driven so far. SUVs, luxury cars, training cars, passenger cars.
I drive at least once a month over 2,000 miles (between two cities) for the past 3 years; snow, rain, Nevada scorching hot road in the summer, etc. I had never, I repeat...NEVER have a tire incident. On this 2,000 miles road trip, over the years I have driven Toyota Highlander, Chev Tahoe, Suburban, Subaru Tribeca B9, Mercedes CLK 500, Mazda Protege, Crown Victoria (most of the time), Mini Cooper, BMW 550i.

I have 5 training cars, all Crown Vics, they all run on 50 PSI (41 sidewall max.)

People like CapriRacer they say there is no empirical evidence that running a tire at the sidewall max. or over is beneficial, but he never presented an empirical evidence that running a tire at the sidewall max. is dangerous, illegal or detrimental to the vehicle or driving performance.

He never presented an evidence that hyperinflation is worst than underinflation.

The only "drawback" while driving on high PSI is a stiff ride.
But as a professional driver, I want my ride to be stiff, I need to feel any vibration of the road or slide of the car thru the seat of my pants.
I don't want a cushy ride so that I will be taken by surprise by an over-steer.

On the other hand, under-inflation of tyres, because let's be serious...at 32 PSI a tire is underinflated, affects many different types of crashes, often in subtle or indirect ways.

Underinflated tires can result in:
• reduced vehicle handling
• increased braking distance
• increased likelihood of blowouts
• increased tire wear

Last but not least, since this is an ecomodder forum, in addition to road safety consequences, underinflated tires can be associated with environment costs such as increased greenhouse gases associated with lower millage per tire, increased fuel consumption and disposal problems.


Please CapriRace tell me (once again) I have the wrong data or I am misinformed or (your favorite) my facts are not straight.

[CapriRacer]

Originally Posted by marinpa

.............People like CapriRacer they say there is no empirical evidence that running a tire at the sidewall max. or over is beneficial............

Please CapriRace tell me (once again) I have the wrong data or I am misinformed or (your favorite) my facts are not straight.

I am not in the habit of defending statements I didn't make, but here's proof I didn't make that statement.

Barry's Tire Tech

The second image on the page is a graph showing the benefits of increased inflation pressure on rolling resistance.

[marinpa]

Originally Posted by CapriRacer

I am not in the habit of defending statements I didn't make, but here's proof I didn't make that statement.

Barry's Tire Tech

The second image on the page is a graph showing the benefits of increased inflation pressure on rolling resistance.

Is it true that OEM tires are designed to give you a comfortable ride in the detriment of fuel economy, traction, and/or treadwear?

The reality is that you are a very knowledgeable individual in regards to the tire subject. But your answers tend to take side with a particular politico-economic position, and your arguments can be swiftly dismantled when it comes to a high end, professional, precision/performance driving environment.

[euromodder]

Originally Posted by marinpa

I have 5 training cars, all Crown Vics, they all run on 50 PSI (41 sidewall max.)

So I'm using the same sort of pressure as your training cars, simply because of the higher rating of my tires, but I bet these cars are heavier than mine at 3100 lbs fully fueled, no driver, no load.

The only "drawback" while driving on high PSI is a stiff ride.

Developing into a bouncy ride when the suspension is cheaply designed, or getting worn.
There definitely is a point where you need to stop inflating the tyres further.
I'm not going to run my rears @ 60psi, it'd be downright dangerous.

Hence, you can't make a generalized claim of running tyres 10psi over their rated pressure without knowing the car and the tyres.

[UFO]

Originally Posted by euromodder

There definitely is a point where you need to stop inflating the tyres further.
I'm not going to run my rears @ 60psi, it'd be downright dangerous.

Hence, you can't make a generalized claim of running tyres 10psi over their rated pressure without knowing the car and the tyres.

I agree. I think that point is either at 90% of the potential mileage gain, or the maximum sidewall rating. Going over that is minimal FE gains and reduced margin of safety.

[marinpa]

Originally Posted by euromodder

So I'm using the same sort of pressure as your training cars, simply because of the higher rating of my tires, but I bet these cars are heavier than mine at 3100 lbs fully fueled, no driver, no load.


Developing into a bouncy ride when the suspension is cheaply designed, or getting worn.
There definitely is a point where you need to stop inflating the tyres further.
I'm not going to run my rears @ 60psi, it'd be downright dangerous.

Hence, you can't make a generalized claim of running tyres 10psi over their rated pressure without knowing the car and the tyres.

When you say running 10 PSI over the sidewall max it'd downright dangerous, what do you base your affirmations on? Where did you get the information that reflects your statement?
Did you make any physics calculations, did you read any specialty literature quoting some empiric evidences, did you performed your own tests, etc.

My friend, I am not saying you are wrong, as I am not saying you are right, but we have to get to the bottom of this without using personal opinions or beliefs based on popular anecdotes spread around by groups with vested political/economical interest.

Wouldn't you wish you see the tire inflation calculations (chart) that tire manufacturer base their methodology of rating the sidewall max?

Do you know where you can find that information/chart? NOWHERE! Why? I am glad you asked. Because that information is kept by the tire manufacturer and deemed "secret" or as they put it "not published due to copyright laws"

Now...what the heck can be so secret about a mathematical formula deriving from 3-400 of years of physics science.

The only reason my friend they don't want you to see or know about the exact formula is because you would be able to figure out that driving at 5-10 PSI over the sidewall is not going to result in a catastrophe, on the contrary is going to save you some money, you are going to run those dam tires 30-40% longer that you do it at 28-30 PSI, you are going to (God forbidden) use less gas and ultimately make a have a positive environmental impact. uuuuuu....that's grimmmmm!!!!!

I might be wrong, I know I don't hold the key to the universal truth, but by the love of God, let not make assumptions based on anecdotal/urban myths, let's use our God given intelligence and, verify and cross examine any pub science coming our way.

Shall we?