Tire Pressure

[mattwithcats]

Original tires on my Saturn were "S" speed rated, and Max of 35 psi.

Current rubber is "H" rated" and Max of 51.

Door says 29 PSI. If I put in 29, I get terrible mileage, terrible handling, and terrible tire wear.

I put in 44 psi rear, 37 front...

42 MPG, 40,000 miles on the tires, with 7/32 left...

 

[andyd]

More PSI reduces contact patch .but stiffens sidewall. Daughter's XC90 gets 5 PSI over door post spec. to keep rassen frassen TPMS quiet.

 

[Wolf359]

Originally Posted by JLTD

This comes up on this board frequently… There are those that say use the manufacturer's recommended pressure, some that say adjust your pressure depending on the load, those that say adjust your pressure based on footprint of the tire, and any other number of methods. In the end, it's your vehicle.



If you read the recommendations out there, most of them basically say whatever the door placard says. Only the extreme ones go with the max on the tire. I think even tire manufacturers will say only to use the door placard.

 

[HangFire]

Originally Posted by ARCOgraphite
Das-Peikko _ I was told today from a reliable source that you should set your cold tire pressure 4 psi below the max pressure printed on the tire. The owners manual recommendation or any sticker specifications on the car pertain to the original tires that came on the car from the factory and no longer apply. With new replacement tires, go by what the tire manufacturer says. That's what I was told today

That is incorrect on multiple fronts. The tire is part of the vehicle springing/busing system. If you run near max sidewall and its 5 -10 psig over door placard, you will hammer strut bearings out of your strut tops and hammer inner tirerod steering rack spherical joints. The vehicle engineers took in o account door placard inflation when designing the suspension.


No... the effect of 5-10 PSI over should be well within the design envelope of your suspension system. If it isn't, say a cheap loaded strut, then it will have issues soon anyway.

 

[HangFire]

Originally Posted by mattwithcats
Original tires on my Saturn were "S" speed rated, and Max of 35 psi.

Current rubber is "H" rated" and Max of 51.

Door says 29 PSI. If I put in 29, I get terrible mileage, terrible handling, and terrible tire wear.

I put in 44 psi rear, 37 front...

42 MPG, 40,000 miles on the tires, with 7/32 left...

Woohoo! By all means, adjust to the new parameters. 44 is a lot, though. How's the ride? What are the new tires?

 

[1978elcamino]

I accidently posted a reply to this topic in my motocross board an hour ago.

 

[Jim K]

It is a common misconception that overinflating your tires will provide more responsive handling and greater fuel efficiency. In fact, over-inflation is detrimental to the tires and can be dangerous.

For the best handling and fuel efficiency, adhere to the manufacturer's optimum tire pressure. Your tire's optimum pressure is specified by your car's manufacturer. It is determined by a series of tests and analyses for each model, and takes into account several factors:

Tire wear and tread life
Driving comfort
Fuel efficiency
Handling
Exceeding the manufacturer's optimum tire pressure is not recommended for the following reasons:

Tires will wear out prematurely. When overinflated, your tires round out on the tread section, causing the center to wear significantly faster than the outer edges. Your tires might only last half the life they normally would.

Overinflation can cause loss of traction. Even in normal conditions, you are more susceptible to losing traction, spinning out or crashing. This is especially noticeable in winter weather.

Overinflation creates a harsher ride. Overinflated tires provide a bumpier ride, so you will feel every dip in the road.

For safety reasons, never exceed the maximum tire pressure embossed on the side

 

[HangFire]

Originally Posted by Jimkobb
It is a common misconception that overinflating your tires will provide more responsive handling and greater fuel efficiency. In fact, over-inflation is detrimental to the tires and can be dangerous.
For the best handling and fuel efficiency, adhere to the manufacturer's optimum tire pressure..
Your tire's optimum pressure is specified by your car's manufacturer.

Not necessarily. Some Vehicle owner's manuals defer to the tire manufacturer.

Also empirical evidence is against you. I have hundreds of thousands of miles of commuting data showing higher tire pressure gives my vehicles better fuel economy. Many others do as well. Try the Fuely website.

Also "over-inflated" does not mean "anything more than the door sticker". Over-inflated can mean more than the tires maximum listed tire pressure, or anything over optimal for that particular vehicle/tire combination that does not result in a good balance of performance factors. Since I've gotten excellent performance,and treadwear from multiple sets of tires that were never run as low as the door sticker, again, empirical evidence is against you.

Finally, if you're here to sell the party line and say do everything only according to the vehicle manufacturer's recommendations, I don't think you'll fit in that well at BITOG. For example we all know that OEM tires are often vendor-specific, lighter weight, thinner tread depth, and generally inferior compared to aftermarket tires. Following your logic, they are optimized and recommended for your vehicle, so you should use only the OEM tires if available. Doing so one would miss out on all the advances and superior performance that can be found by paying for a better tire. I reject that entire line of thought.

Originally Posted by Jimkobb
For safety reasons, never exceed the maximum tire pressure embossed on the side

There's a huge amount of latitude between door panel and maximum tire pressure embossed on the side of the tire.

 

[RDY4WAR]

Originally Posted by Jimkobb

Exceeding the manufacturer's optimum tire pressure is not recommended for the following reasons:

Tires will wear out prematurely. When overinflated, your tires round out on the tread section, causing the center to wear significantly faster than the outer edges. Your tires might only last half the life they normally would.

Overinflation can cause loss of traction. Even in normal conditions, you are more susceptible to losing traction, spinning out or crashing. This is especially noticeable in winter weather.


...and yet I have noticed exactly the opposite. My tread life went up when I increased the tire pressure. There is no excessive wear anywhere on the tires. MPG has certainly improved. It will coast easier meaning less throttle input, especially going downhill. Max tire pressure on sidewall says 44 psi. I run them at 40 psi, and they pass the chalk test just fine there.

The door and manual says 30 psi, but the tires bubble pretty noticeably at that pressure, and it drives like a water bed. It rides so much better at the higher pressure. Traction hasn't changed at all. In fact, it acts more stable on wet roads. It doesn't snow down here so no comment on that.

 

[oil_film_movies]

Originally Posted by Jimkobb
It is a common misconception that overinflating your tires will provide more responsive handling and greater fuel efficiency.
In fact, overinflating above the placard WILL produce better handling and MPG.

Maybe you missed the facts posted earlier:
Originally Posted by bubbatime
……. Take two identical police patrol cars. Put one car at 30 PSI. Put the other car at 45 PSI. Put them on the police driving obstacle course, with the same driver. The one with 45 PSI in the tires will absolutely smoke, stomp, and out corner the car with 30 PSI in the tires, and have better lap times. Not even close. I know this for fact, as it was demonstrated to us in the police academy, the importance of tire pressure. The 45 PSI car handled very nicely. The 30 PSI car, wallowed all over the place.


Originally Posted by Jimkobb
In fact, over-inflation is detrimental to the tires and can be dangerous.
No, it depends on how crazy you go with "overinflation". Staying under -4psi from max sidewall pressure is not a problem. You're hyperventilating about this.

 

[Quattro Pete]

Originally Posted by HangFire
Not necessarily. Some Vehicle owner's manuals defer to the tire manufacturer.

Do any tire manufacturers recommend to run their tires at the max PSI listed on the tire sidewall?

 

[555]

There is no hard fast rule for every vehicle out there. There just isn't . Perhaps fun to discuss but one philosophy does not apply to every vehicle or even category of vehicle.

 

[Rmay635703]

Originally Posted by Quattro Pete
Originally Posted by HangFire
Not necessarily. Some Vehicle owner's manuals defer to the tire manufacturer.

Do any tire manufacturers recommend to run their tires at the max PSI listed on the tire sidewall?


Tire manufacturers recommend nothing but how to mount. Some OTR and military tires state a pressure vrs weight rating relationship .

But they do state what not to do
Like not to run under inflated tires and to not overload or overspeed tires.

All highway blowouts are normally attributed to the effects of under inflated tires or punctures.

Yet everyone here is perfectly happy running a couple psi above the pressure that causes heat related blowouts.

In the case of the Exploder the placard was only a few psi above the lower minimum "blowout" pressure.
Any small variations in pressure or load would put the tire into the danger zone where it would overheat and blow.

The effects of too low of a pressure are imminently dangerous, higher pressures (up to the rating)
if anything are as safe if not safer than the placard pressure albeit not as comfortable .
If your tire has a slow leak or you expect a lot of temperature variance being above the door placard is infinitely safer than setting for the placard and running low afterward

 

[ARCOgraphite]

I ran the wife's subaru at 3psi over door placard and the center 1/3 of the contact patch is worn to the treadwear bars now at about 45K miles.

In fact i have to get new tires. next month

More Yoko's? or ?

 

[ARCOgraphite]

I suppose you want a photo.

 

[JohnnyJohnson]

Originally Posted by ARCOgraphite
I ran the wife's subaru at 3psi over door placard and the center 1/3 of the contact patch is worn to the treadwear bars now at about 45K miles.

In fact i have to get new tires. next month

More Yoko's? or ?


LOL my God ARCO and it didn't even blow up. You'd better buy a Lotto ticket.

 

[ARCOgraphite]

Looking closer - they don't look too bad. Just VERY slightly more wear in the center.
This is the worse one right now: passenger side front.

Car has always been in good alignment and no adjustments to alignment were required.

5000 more highway miles left on them?

 

[ARCOgraphite]

Originally Posted by JohnnyJohnson
Originally Posted by ARCOgraphite
I ran the wife's subaru at 3psi over door placard and the center 1/3 of the contact patch is worn to the treadwear bars now at about 45K miles.

In fact i have to get new tires. next month

More Yoko's? or ?


LOL my God ARCO and it didn't even blow up. You'd better buy a Lotto ticket.

I did get 5 quick picks on the powerball for last wednesday. Only got 2 numbers

I wouldn't know what to do with 3/4 of a Billion Dollars ( pre-tax). at my age anyhow.

Free Asian Massage for all the forum members?!

 

[JohnnyJohnson]

Originally Posted by ARCOgraphite
Originally Posted by JohnnyJohnson
Originally Posted by ARCOgraphite
I ran the wife's subaru at 3psi over door placard and the center 1/3 of the contact patch is worn to the treadwear bars now at about 45K miles.

In fact i have to get new tires. next month

More Yoko's? or ?


LOL my God ARCO and it didn't even blow up. You'd better buy a Lotto ticket.

I did get 5 quick picks on the powerball for last wednesday. Only got 2 numbers

I wouldn't know what to do with 3/4 of a Billion Dollars ( pre-tax). at my age anyhow.

Free Asian Massage for all the forum members?!


LOL you could have suffered through it trust it would have come to you. I know it wouldn't be a issue for me. First I'd disappear and go on vacation someplace no one knew me for a few months.

 

[HangFire]

I think the effect of higher pressure differs with different tires. I've seen charts of tire wear indicating greater edge wear on overinflated radial tires. It kind of makes sense if you think of there being the strongest belts below the tread, less/lesser belts in the sidewalls, and the tire will swell around the edge where the thin sidewall belts curve to meet the strong tread belts.

But take a really low profile, very wide tire, it's gotta have some balloon effect in the middle.