Tire pressure check method??

[MADDOGSI]

OK my fellow members.A argument has come about how to check air pressure in tires.I know this is silly but I want to hear from people.OK here it is. A member on here wanted to know what tire pressure he should run. I advised to run 38-40 psi which is a running pressure. Since damn near all people check tire pressure when they are filling up with gas or they notice a tire looks low.Which at this point the tires are at a running temp.The by the book way to check tire pressure is cold.But most people don't check tire pressure cold and be able to adjust it then and there so they must drive some where to add air.Now the tire's are warmed up.So if you adjust the pressure to the owners manual or the sticker in the door jam which states 32 psi. 32psi in a warm tire would be under inflated because tire pressure drops when cold.So knowing the running pressure of the tire is a good thing to be able to adjust the pressure when you are out and about. So I advised the running pressure for the way to adjust to save the headache of trying to set the tire pressure cold.In this event another member jumped my sh*t and said running pressure is way wrong and anybody that sets their tires this way is stupid and a idiot.So he burned me with bad rep. He continued for several hours to say over and over again that it is written here, here and here that the correct way to set tire pressure is cold and any other way is incorrect and leave you with wrong tire pressure. Well I'm a tech for a living and i tried to explain that the average driver checks his or her tire pressure when it is warm. He replied I was a joke for a tech and basically should not be working on people's cars or trucks.So by me advising a member to set his tires at the running pressure rather then confuse him about making sure his tire's are cold to adjust his pressure.He then again replied a person should take the tire pressure cold and if no access to an air compressor or such to subtract the tire pressure from the OEM spec.drive to a fill station. and only add the psi to each tire from the answer you got as the difference.So here's the example:you check your tires and find one tire is at 25 psi.the spec cold is 32 psi.SO the tire is 7psi low. You drive to a gas station(which warms the tire up)and you check it again now the psi is at 32 psi from being warmed up.You know the tire was 7psi. You add 7psi and now the tire pressure is at 39 psi.HUmmm and I recommend to run 38-40 psi running pressure. SO did I really give wrong info??? which brings me to my point. I would like a hear how many members set their tire's completely cold and use exactly what is written in the books. Or do you set tire pressure at a warm running temp pressure??

If a MOD could do a poll that would be great.

1. set tire pressure with tires cold
2. Set tire pressures at running temp pressure.

Now keep in mind that running temp is 6-8psi higher then cold pressure.So would you set your tires pressure at the convenience of running temp psi or do you make the effort to set the pressures with the tire cold and use exactly what the OEM suggest? Let's keep the answers unbiased and straight forward with your thoughts of the two methods and what works best for you.

[Zeuceone]

if a tire looks low to me i drive to the gas station and fill it to 40 psi.

[MADDOGSI]

Originally Posted by Zeuceone

if a tire looks low to me i drive to the gas station and fill it to 40 psi.

For the most part that is what most people do. I got burned at the stake for saying such a thing.

[Bartman619]

...or you could inflate all tires to 40psi at the gas station, then drive home and leave the car parked for a couple of hours to let the tires coo...then adjust the tire pressure to 32psi or to whatever the doorjamb sticker says....my 2 cents.

[Yodums]

You're absolutely correct. The only way to get an accurate "cold" rating into the tires is filling up when the tires are warm, letting the tires cool over a period of time and deflating them to whatever psi you want. You will skew the readings of the tire pressure reader if the car is driven at all.

[Sli(ks]

Originally Posted by Yodums

You're absolutely correct. The only way to get an accurate "cold" rating into the tires is filling up when the tires are warm, letting the tires cool over a period of time and deflating them to whatever psi you want. You will skew the readings of the tire pressure reader if the car is driven at all.

Are you sure about not driving it at all? I mean I usually drive to a gas station that's like 3/4 of a mile from me, never thought 3/4 of a mile would really matter. The engine isn't even usually warmed up when I get there.

[BLU BY U]

i use helium in my tires to limit rotational mass.

[2006exsedan]

sigh ... just couldnt give this up could you LOL

you are now changing your story

the original argument you and I had was

WHAT IS THE CORRECT WAY TO MEASURE TIRE PRESSURE ... THE MOST ACCURATE ...

NOT

WHAT IS THE BEST WAY TO FILL UP TIRES

and as I said before... and Ill stand by it


THE MOST ACCURATE WAY TO GET A PSI RATING OUT OF A TIRE - IS A COLD READING ... THIS HAS NOTHING TO DO WITH ADDING AIR

you tried to tell me that you can get a more accurate reading by measuring PSI when the tires are hot vs cold .. and thats TOTAL BS

so dont try to make it something it isnt


and like i said in the other thread

explain to me why NUMEROUS SITES ... the DEPARTMENT OF TRANSPORTATION being one ... recommends for the most ACCURATE reading to measure cold psi

i think you are confusing most accurate with most convenient ... just because the average joe measures his tire temps when hot .. dosent make it the most accurate or the right method

and another thing to keep in mind

when the OP asked what he should run .. i am assuming these are new tires ... when he gets these mounted ... and they add air .. explain to me how they are going to add air at HOT PSI .. its going to be a COLD PSI measurement and if he went in there and said .. give me 40 PSI .. that would be disaster

[Vince]

I see your point, although the correct method always has and always will be to check them cold. It's debateable about tires and how much driving is necessary to reach a running temp as different brands and models of tire build heat at different rates.
Cold check is the only way to do it in my book. But again I do see your point and it makes some sense.

[2006exsedan]

Originally Posted by Vince

I see your point, although the correct method always has and always will be to check them cold. It's debateable about tires and how much driving is necessary to reach a running temp as different brands and models of tire build heat at different rates.
Cold check is the only way to do it in my book. But again I do see your point and it makes some sense.

THANK YOU .. finally someone understands this ...

that HOT PSI is a variable number ... there are lot of things that determine how hot your tires are ... how far you drive.. brand of tire... temp outside .... you wouldnt get the same measurement if you did it 10 times

where as the COLD PSI ,... is STATIC ... its unaffected by the above mentioned and will yield the most accurate readings time after time

hence the reason is recommended by everyone .. including DOT

Convenience does not equal accuracy

[gbae007]

That's pretty wordy.

It's simple. Buy a digital guage ($10) and check your tires first thing in the morning prior to driving. I inflated to 32psi cold but you can stay within the manafacturers recommended range depending on your intentions (fuel economy, more grips, etc.)

[Yodums]

Originally Posted by Sli(k

Are you sure about not driving it at all? I mean I usually drive to a gas station that's like 3/4 of a mile from me, never thought 3/4 of a mile would really matter. The engine isn't even usually warmed up when I get there.

That's the thing, there's no real easy way to see how much of an effect driving 3/4 of a mile will do to your readings, so that's why I just threw out the statement that any driving will affect those readings. I know what you mean though, I live less than a kilometer away from a gas station, so I've always wondered the same thing.

[2006exsedan]

yeah - even driving 1 mile will affect readings

*taken from DOT*

While some people think that the term “cold” tire relates to the outside temperature, it really has nothing to do with the weather. It can be 90 degrees outside and your tires can still be considered cold. Rather, a cold tire is one that hasn’t been driven on for at least 3 hours, which is the optimal time to get an accurate pressure reading. A tire that has been driven on for short distances — even just 1 mile — is no longer considered “cold.”

[GalaxyGreySi]

OK - I am a Honda technician as well, so I will throw my 2 cents in. Honda states that the best way to check tire pressure is when the tire is cold, HOWEVER - in the literature that was dropped off by the district service manager sometime ago, AHM states that for the most part, this is impractical, and tire pressure should be filled to 6 psi more than the cold tire pressure, so, in a civic, this would equal a running tire pressure of 38 psi, which is what I set them to if the car has been sitting for less than an hour. Since AHM thinks that this method is perfectly acceptable, and states this recommendation in the literature that they are handing out to their factory service techs, AND it ALSO states this on the IN ("the IN is honda's online resource for honda personnel, short for Interactive Network, contains service bulletins, repair procedures, warranty times, etc.), so if this method is good enough for Honda, then it's good enough for my customers. NOT good enough for me though. As enthusiasts, we are definitely more picky about accuracy than the average honda owner. I set my tires cold, bitch! Whoever thinks that setting tire pressure when they are hot is more accurate needs some common sense knocked into their head. I hope that guy never does my oil change.

[twistedframe]

Unless using nitrogen tires pressure can only be accurately checked cold. Every ten degrees raises the pressure 1 psi. So unless you carry around a pyrometer in your car there is no way to now how hot your tires have become. The only way you can get an accurate hot reading is if you are using nitrogen which doesn't change pressure with heat.

[MADDOGSI]

I think the term cold tire pressure is misunderstood.Cold tire pressure is only a certain pressure at a certain temp.SO what is cold tire temp? Obviously a cold tire temp in Alaska will be different then a cold tire temp in Arizona if there is a 90 degree Ambient temp difference.The term cold in this application means 75 F ambient temp which is the national average industry standard temp.I finally found the info.
This is quoted straight from the Bureau of transportation statistics and EPA.
"factors are national averages based on the following assumptions: ambient temperature 75 ºF, daily temperature range 60 - 84 ºF"

I guess if a guy wanted to be dead on the tire temp needs to be Ambient temp of 75 degrees for cold pressure to be set.The cold pressure is merely a guideline to start with.vehicle weight,suspension etc.. can change this point. In general to get the best pressure to run a person needs to adjust pressure to get even wear and most road contact.once the pressure is found that meets even wear and best road contact record that pressure and temp.That is the term cold temp setting for your application.Honda found that a 32 psi average for the industry standard temp of 75F showed best wear and road contact for the stock tires on the FG.If you still run in stock form then this will still apply. If not stock your setting will be different. To find out where your pressure should be. Make a chalk line about 1/2 wide across the tread.Drive the vehicle about 10 miles or so,keep speed on average around 30-50mph if too fast the tire expands from the centrifugal force and give you a inaccurate reading.Then look at the chalk line.If it is worn off evenly your pressure is set correctly.If worn on the outside more then in, then it is under inflated. Worn inside more then outside means over inflated. adjust until the chalk line wears off even and you have the pressure you want.record the temp and pressure now you have the cold temp rating.Again cold is the base from those temps and pressure. If the tire heats or cools above or below the pressure will change,but as long as the pressure comes back to base at the recorded temp, tire pressure is correct. I have always called this running pressure since you are setting pressure for correct wear and road contact for a certain temp for consistency.

[2006exsedan]

ill post my last reponse to this waste of a time thread

this whole issue came about because you tried to argue with me that

it was more accurate and efficient for someone to measure tire pressure when the tires were "hot" vs "cold" PLAIN AND SIMPLE

that IS WRONG ... and that is what i was trying to prove....

obvisiously there are many factors that can determine how hot or cold a tire is ... but the bottom line is .. you need a BASE NUMBER to start with ... and the more accurate base number is when a tire is COLD ... not a tire that has been driven since there is more likelyhood for that number to be skewed since there are more factors involved in affecting the "hotness" of a tire vs a "cold" tire.

im not even sure why this second thread was made but i think you will find if you go back to the first thread .. my original point was

to get the most accurate reading of tire PSI ... you should measure them cold ... ie; not having been driven on .... which is what you tried to dispute by saying that it was better to do it after the tire was hot ... which you have admitted was wrong

while i will agree for the average joe .. its prolly more convenient to do it hot since most people dont think to measure tire pressure before they drive the car or they might even notice that they need air till they have already driven the car ... but it still dosent change the fact that the more accurate method is still COLD ...

so why dont you let this thread die ... there have been numerous people here .. who have backed up my claim about which is more accurate and i have sited numerous links.

[gbae007]

Originally Posted by 2006exsedan

ill post my last reponse to this waste of a time thread

this whole issue came about because you tried to argue with me that

it was more accurate and efficient for someone to measure tire pressure when the tires were "hot" vs "cold" PLAIN AND SIMPLE

that IS WRONG ... and that is what i was trying to prove....

obvisiously there are many factors that can determine how hot or cold a tire is ... but the bottom line is .. you need a BASE NUMBER to start with ... and the more accurate base number is when a tire is COLD ... not a tire that has been driven since there is more likelyhood for that number to be skewed since there are more factors involved in affecting the "hotness" of a tire vs a "cold" tire.

im not even sure why this second thread was made but i think you will find if you go back to the first thread .. my original point was

to get the most accurate reading of tire PSI ... you should measure them cold ... ie; not having been driven on .... which is what you tried to dispute by saying that it was better to do it after the tire was hot ... which you have admitted was wrong

while i will agree for the average joe .. its prolly more convenient to do it hot since most people dont think to measure tire pressure before they drive the car or they might even notice that they need air till they have already driven the car ... but it still dosent change the fact that the more accurate method is still COLD ...

so why dont you let this thread die ... there have been numerous people here .. who have backed up my claim about which is more accurate and i have sited numerous links.

If you're going to be so angry, then at least use punctuation.

It's the Internet, if you want "professional" advice to talk to your Honda service people. This isn't earth breaking shit, it's tire pressure.

[2006exsedan]

Originally Posted by gbae007

If you're going to be so angry, then at least use punctuation.

It's the Internet, if you want "professional" advice to talk to your Honda service people. This isn't earth breaking shit, it's tire pressure.

useful post LOL

im not in english class .. im sure the lack of punctuation is ok

im too tired to care about that

anyways ... my point is ...let this thread die ... i tried before and MADDOGSI decided to continue it further ...

[IMTHEPUNISHER]

Simple Formula: A "cold"-pressure tire will expand or contract roughly 1-psi for every 10 degree change in it's temperature. A tire is defined as "warm" when it has been driven in excess of 3miles. Driving on the highway for an extended period will raise a tire's temp. at least 30 degrees or better (depending on it's inflation). Hence, if somebody "maxed-out" their pressure, per the side wall's rating, the tire will expand at least another 3psi OVER THAT when actually driven. 40psi max. becomes 43psi (or higher) etc. Do the math.