Tire pressure

[GunnyGene]

37-38 or even 40-42 is nothing to worry about when the tires are hot. You'll get a little rougher ride is all, and maybe save a little gas. Recommended cold tire inflation is designed to give a softer ride without sacrificing optimum mpg. Don't sweat it unless your running the Nascar circuit. Also, I wouldn't believe the sensors. Use a quality tire gauge.

 

[tinman]

Beginning in 2003 all vehicles sold in the USA have a tire inflation data sticker on the drivers side door or door jamb......usually near the the VIN plate. Those numbers only apply to that vehicle and the exact size tires that came from the factory. To be on the safe side, go by the numbers on the tire..........especially if you go to a different type of tire...........and always use a quality tire gauge.

 

[hittman]

What to do?

Quit obsessing over it.
If recommended PSI on the sidewall of the tire is 35, put in 35 and walk away. You're done.

 

[Pat-inCO]

Is that operating pressure or ambient (standing) pressure?

If your vehicle has been standing, say overnight, is not in the sun, check
the pressure. Adjust to recommended as necessary.

Keep in mind that if the temperature during the day, in the sun, going
down the road WILL be higher. The manufacturers take that into
consideration when they make their recommendation.

Remember that a tire with higher pressure actually runs a bit cooler,
because there is less flex in the side-walls as you drive. As hittman said,
there is no reason to obsess over it. In fact, since you are talking about
AZ, you will have far more problem from sun damage, than from the
variations in pressure.

Check them regularly (I'd say once a month, unless you are seeing
significant variations), adjust if necessary (most likely not), and relax.

I've had problems with ONE set of tires in the last forty years. I've also
had several sets that required pressure adjustment no more than every
six to eight months.

P.S. I was told by the service guy at the car dealership that for each ten
degrees in air temperature, there is a . . . one . . . pound difference in the
tire. I'm not sure he was exactly correct, but if he is at least close . . . .

 

[RSIno1]

when we ran an SCCA showroom stock class that had to use street radials we ran 50 psi cold just to get the sidewalls stiff enough to corner. never had a failure.

 

[exavid]

We have a Chevy Equinox and a BMW C650GT maxi-scooter. Both are equipped with TPMS. I just set my vehicle's tire pressure to the recommended pressures and not the TPMS reading. Then I just note the TPMS reading what ever it happens to show. I just use the remote reading to spot any major changes or note if one tire is a lot lower than the others. On my bike I just look at the difference in pressure between the two tires. When properly set there's six PSI difference between front and rear tires. As long as the pressure difference stays at six PSI or very near it I know everything is okay. You can't depend on the actual readings with these things as they vary depending on barometric pressure and temperature but the do a good job showing changes.

 

[coach]

I've always heard the tire pressure is for the ambiant temperature not when hot from driving. I'd much rather have the pressure get a little higher when highway driving rather than low for short trips around town.

 

[exavid]

That's a fact, tire pressure should be checked when the car's tires are cool. If you set them hot they definitely be too low in normal use.

 

[JFB]

for gas pressure, PV=mRT is like the "pie are square"

to compare pressure to temperture changes it can be solved for P/P=T/T
so for a tire at 30psi at 70F that heats up to 170F with driving, the pressure goes up to 35.7
IF it is dry air. all bets to what the pressure is IF the air is "wet", Thus the big reason to use dry nitrogen instead of air from a compressor

 

[daveg.inkc]

You want to set the pressure when cold. I adjust the pressure in my tires to get full tread contact. That figures to be 34 psi on steering. 30 on rear of F-150. I get 7, 8 years out of my tires. I want the tread contacting road right to the very edge of tread.

 

[Montelores]

The tire inflation information sticker should read "Cold Tire (Inflation) Pressure."

Tire pressures are typically checked when at cold / ambient temperature.

I believe that underinflated tires are the most common car maintenance issue in the U.S.

The survey found that 85 percent of motorists do not know how to properly inflate tires.

http://newsroom.aaa.com/tag/tire-safety-fact-sheet

Keeping your tires properly inflated is one of the easiest ways to help maintain good gas mileage and extend the life of your tires. Check your car’s tire pressure at least once a month with a quality gauge, that measures pressure in pounds-per square inch (psi). Three types of tire pressure gauges are available at most auto parts stores: digital, dial and pen/stick types. The digital and dial designs tend to be more accurate and easier to read, although a good pen/stick gauge will do the job as well. Pressure gauges built into air hoses at gas stations are often abused and frequently inaccurate.

Recommended tire pressures are for cold tires. Therefore, tire pressure should be checked at ambient temperature before the vehicle has been driven. Checking tire pressure on a car that has warm tires can result in a pressure reading of up to 5 psi higher than the recommended pressure. The recommended inflation pressures for your car’s tires can be found in the vehicle’s owner’s manual or on the tire information decal attached to the driver’s door jamb. On older cars the decal may be in the glove box or inside the fuel filler door.

http://exchange.aaa.com/car-care/repair-maintenance/tire-safety-and-maintenance/#.WdmhFtFOmhA

Also, the pressure information on the tire sidewall is generally the MAX (maximum)
cold inflation pressure approved by the tire manufacturer.

https://www.michelinman.com/US/en/safe-driving/tire-safety/tire-pressure.html

Hope this helps -

Monty

 

[gunzo]

It could be tricky to do with tires that are already on the car because of the presence of moisture, but, if the tires were dry inside, they could be inflated with nitrogen. Then, the pressure changes at different temps would go away.

 

[daveg.inkc]

NASCAR uses nitrogen. And I read an argon/nitrogen mixture. Nitrogen is approx 75% in atmosphere. NASCAR tires run 20 psi to 45 psi in race tires. And they adjust 1/2 lb at a time. I would like a precise gage like that.

 

[Johnnu2]

Would anyone like to take a guess regarding what percent of the US population ever checks their tire pressures, OR their oil...? I don't know the answer, but if I were to guess I would say maybe 10% (?)

J

 

[vito]

Reading what is on the side of the tire is not very helpful. Every tire that I have had shows the MAXIMUM air pressure for that tire, not a recommended pressure. I think the best bet is to go by the sticker on the door post of the driver's door, plus a few pounds of pressure. My Dodge Durango's sticker says 33 psi front and 36 rear. I actually inflate (cold) to 36 psi front and 39 rear and that seems to work really well. The TPMS often shows actual running psi as much as 37 or 38 front and 42 or 43 rear which is not an issue at all.

 

[gunzo]

Pickup trucks are two faced.

When loaded they need more rear tire pressure, when empty, the rear is a lot lighter than the front & adjusting accordingly will offer a better ride with no premature tire wear.

 

[DGW1949]

Far more radial tire failures have been caused by under inflation than by over inflation. That is mostly because under inflation causes both the side walls and the tread area to flex too much, which in turn not only causes excess heat, but eventually causes cracks/breaks in the cord and tire carcass.
Plus, bear in mind that the max weight-carrying capacity of any given tire is calculated by the tire manufacturer as being X-amount of weight @ X-amount of tire pressure, and is expressed as such right on the sidewall of the tire itself. When I look at those figures, and then compare them to the PSI-figures that my vehicle manufacturer is recommending I use, what that tells me are three things:

It's the air inside my tire that's keeping the weight of my vehicle up off the pavement, not the tire itself.
The guys who made my particular tires know more about them in terms of optimum pressure and/or load carrying ability than the guys who manufactured my vehicle.
Apparently, the guys who made and sold me my vehicle are more concerned with me having a nice soft ride than they are with me traveling/hauling stuff from point-A to point-B as safely as possible.

I mean really...given that the vehicle manufacturer has no way to know how I'm actually using their product or under what conditions, let alone what actual brand/type of tire I'm using to do it...who should I listen too...them, or the guys who made my tires?...Not that hard of a decision if ya ask me.

Not saying that everyone one needs to stand back and throw 45-50 PSI into the tire of a compact car just because that's what the tire indicates, just saying that it should be obvious that the 24-28 PSI often seen on door stickers or in manuals probably ain't near enough. So think it over, use some common sense, and as others have said...do use a known-good gauge.

DGW

 

[GunnyGene]

Far more radial tire failures have been caused by under inflation than by over inflation. That is mostly because under inflation causes both the side walls and the tread area to flex too much, which in turn not only causes excess heat, but eventually causes cracks/breaks in the cord and tire carcass.
Plus, bear in mind that the max weight-carrying capacity of any given tire is calculated by the tire manufacturer as being X-amount of weight @ X-amount of tire pressure, and is expressed as such right on the sidewall of the tire itself. When I look at those figures, and then compare them to the PSI-figures that my vehicle manufacturer is recommending I use, what that tells me are three things:

It's the air inside my tire that's keeping the weight of my vehicle up off the pavement, not the tire itself.
The guys who made my particular tires know more about them in terms of optimum pressure and/or load carrying ability than the guys who manufactured my vehicle.
Apparently, the guys who made and sold me my vehicle are more concerned with me having a nice soft ride than they are with me traveling/hauling stuff from point-A to point-B as safely as possible.

I mean really...given that the vehicle manufacturer has no way to know how I'm actually using their product or under what conditions, let alone what actual brand/type of tire I'm using to do it...who should I listen too...them, or the guys who made my tires?...Not that hard of a decision if ya ask me.

Not saying that everyone one needs to stand back and throw 45-50 PSI into the tire of a compact car just because that's what the tire indicates, just saying that it should be obvious that the 24-28 PSI often seen on door stickers or in manuals probably ain't near enough. So think it over, use some common sense, and as others have said...do use a known-good gauge.

DGW

Another thing: Nitrogen vs ambient air. Imo nitrogen is a scam. The atmosphere is 78% nitrogen anyway. Ambient air is very slightly more sensitive than Nitrogen in terms of pressure variation due to temp. changes. Commonly air pressure changes by 1psi per 10deg F. of temp change. Pure nitrogen is pretty close to that. Again, unless you're screaming around a track at 200mph a couple psi one way or the other isn't going to make any difference in tire performance.

 

[Lngstrt]

What does "quality gauge" mean. I asked the Discount Tire guy once what they used. He handed me one of their pencil style ones.

As sort of an aside here ...

Remember the Ford Explorer/Firestone tire pressure controversy about twenty years ago? Vehicles flipping etc. The bottom line was under inflation to provide better ride. Both Ford and Firestone recommended the common 32-ish pounds instead of the 26-ish on the door panel sticker.

So ..... in 2005 I bought a nice used Explorer. I remembered the tire issue. I called the local Firestone dealer and asked what pressure to pump in and ......

The dealer said: "There's a label on the door frame that will tell you the recommended pressure".

Sure enough, the label on the door frame said "26 psi". The original label was still there!!

I always wondered why the Explorer issue never recurred in the used market. Maybe it was never there in the first place.

 

[GunnyGene]

What does "quality gauge" mean. I asked the Discount Tire guy once what they used. He handed me one of their pencil style ones.

Any gauge that is accurate within .5 psi give or take. Which is 99% of all the dial and digital gauges on the market. Stick gauges are usually accurate within 1psi or so.

More important than absolute pressure (somewhere in the low to mid 30's for passenger cars - I keep mine at 35 +/- cold) is maintaining a reasonable equality between left side and right side. 5 or 6 psi difference in the front tires will cause the car to drift left or right for example. Which is why you see the pit guys in Nascar get fussy about left & right side pressures.

 

[Rick Courtright]

Hi,

I use the door sticker pressure for starters:

Tires should be cold. That means they haven't been run in at least 3 hours. And haven't been sitting in the sun for those 3 hours, either! I usually check after dark or first thing in the morning. Then I add about 2 psi to the sticker--it's not unusual to have daily temperature spreads approaching 50 deg F around here at some times of the year, so I want to have the minimum on the sticker at the lowest temp I expect to encounter. I use one of these gauges, which can be eyeballed to 1/2 psi easily enough on the gauge (which is also about the limit of their accuracy):

https://www.ghmeiser.com/dial-gauges.htm (mine's the S60X)

Those numbers on the sidewall are "maximum cold inflation pressure." The vehicles I drive would shake your teeth loose at the 44 psi most passenger tires I see today use as their max.

As for that 26 psi problem on the Explorers back when, I'm not defending Ford's engineers for spec'ing such a low pressure for the type of vehicle and use, but it was probably enough, IF the driver always made sure that's what was in there, and never ran them low! One of those "...but it worked on paper" engineering problems? But too many people run around 2-5 psi lower than the sticker far more often than they realize (hence those stupid monitors?) Radial tires don't like that at all... and there's a cumulative damage problem that can creep up on the driver...

Rick C

 

[salaguinto]

I never do. I rely on the service station to rotate my tire every 10k miles, oil change every 6k miles, anti-freeze every 2 years. I turn in my leased car when it hit 30k miles or so. Never a headache.

 

[Bull Barrel]

Na$car is fussy about L/R tires because there may be a compound difference plus usually a diff in diameter. L side tires are smaller, helping the car turn. This is called, "stagger".

 

[The Norseman]

Thank you for starting this Topic.

It reminded me to check my Pickup Tires.

We are getting into the Cold Weather now,
and my tires were 4 pounds low.

My new Jeep Cherokee tells us pressure
so I just page to the monitor and look,
their Ok.

Thanks again.

 

[Fox Mike]

Another thing: Nitrogen vs ambient air. Imo nitrogen is a scam. The atmosphere is 78% nitrogen anyway. Ambient air is very slightly more sensitive than Nitrogen in terms of pressure variation due to temp. changes. Commonly air pressure changes by 1psi per 10deg F. of temp change. Pure nitrogen is pretty close to that. Again, unless you're screaming around a track at 200mph a couple psi one way or the other isn't going to make any difference in tire performance.

In SOLO we determined how to keep only the tread contacting the road. Place three equidistant chalk marks on each tire from the tread down to the sidewall. Drive the normal course and if the chalk was worn away on the sidewall we inflated and ran again till there was no wear shown on either the sidewall OR the very side of the tread. Now only the flat surface of the tread is touching the surface of the road. Sometimes this difference was a 1/4 pound of air one way or the other. In SOLO the car was rarely, if ever, run higher than second gear. The ride sucks but the tires perform great.

 

[mohavesam]

The TPI units on your wheels have been calibrated to the sensor computer, which lights up your dash warning lights, etc. Go with the door sticker (presuming you haven't been sold a different TPI when changing tires, etc. They are not exactly NASA-quality sensors, more like a dime-a-dozen.

Buy a good dial-type tire air pressure gauge and check them at rest - You're instantly a genius compared to 90% of the drivers out there. And tech your children well. Nothing good can come from a blowout-rolllover into oncoming traffic...

 

[blume357]

I run about 65lbs in my vehicle...... and yes... if the road is rough, which is just about everywhere here in S.C. because the number of cars on the road has doubled in the last 10 or so years and the S.C. highway dept. is about as 'poe' as you can get, I get a pretty rough ride... but If a rear tire is under inflated the back end will tend to wander.

 

[exavid]

I find 70% nitrogen works well in all my vehicle tires.

 

[Galaxiedan]

Im very strict about using 78% nitrogen in my tires

 

[Rick Courtright]

Im very strict about using 78% nitrogen in my tires

Hi,

Same here... it's worked for decades! I like that it's interchangeable between the cars and bicycles, I can still use my old metal valve caps, and a side benefit is it can be compressed to rather high pressures and used for cleaning stuff.

Rick C