HELP! Few questions about "Tire Pressure"

[Solodays]

I have this tire gauge here:
http://img293.imageshack.us/my.php?image=gaugeop8.jpg

and here are fews questions...

1:when it's winter time around 20degrees outside, does the air pressure on the tires gives an accurate outcome when measure with a tire gauge?





2: on my tire gauge it didnt lable psi but it lable lb, how do i know how much air pressure to pump? just wanna make sure does 30 on the tire gauge represent 30 psi?





3:have 2 vehicles. 1 is a car at 32psi and the other is suv at 26psi, howcome the car intakes more psi than the suv, isnt it the other way around since suv's are bigger and weights more?


4: my tire gauge is not very accurate, it doesnt always give the same result. how is the correct way of measuring it, do you push and pull quickly or just hold for few seconds and pull away?

 

[d33pt]

1. when it's cold out, the tire pressure will be a little lower than it should be. not too much though. maybe 1 psi.

2. PSI stands for Pounds per Square Inch. So 30 lbs is 30 PSI on your gauge.

3. It all depends on the tire. Go by what the manufacturer recommends on the doorjamb.

4. get a good dial type gauge that holds the pressure until you release it. You push it on the valve hard until air stops leaking out. do not use a pencil type gauge. those are highly inaccurate.

 

[Chaotic42]

The tire gauge will report the pressure in your tire. At 20F, that pressure will be lower, with all other things constant, than at 70F. That's just physics.

Your gauge should be in PSI, even if it just says pounds.

You need to check the doors of your vehicles for proper tire pressure. There should be a stucker or metal plate that tells you what to inflate your tires to. Live by that number and check your tire pressure twice per month or more.

You should be able to hold the gauge steady on the stem and get a constant pressure. If not, invest the $.99 in a new pressure gauge. It's very handy and there's no excuse for not having one that works.

 

[dj2004]

I suggest a digital one. Easy to read and keeps the PSI on screen for a few secs.

 

[Solodays]

Originally posted by: d33pt
1. when it's cold out, the tire pressure will be a little lower than it should be. not too much though. maybe 1 psi.

yes, i know that when the temperture drops 10 degree you will lose 1 psi, but despite all the cold, will the tire still give an accurate measure using a tire gauge when its super cold out?

4. get a good dial type gauge that holds the pressure until you release it. You push it on the valve hard until air stops leaking out. do not use a pencil type gauge. those are highly inaccurate.

pencil type gauge HIGHLY INACCURATE? what type do you use?

i was thinking of getting this one...http://www.drivegreen.com/productkt.shtml

 

[Itchrelief]

3. By any chance is the SUV a Ford Explorer? Ford specified a somewhat low tire pressure for Explorers (most vehicles seem to recommend about 30 psi) for the model years affected by the Firestone tire recall. Crappy tires + already low suggested tire pressure + people letting tire pressure go low = highway alligators.

4. I hate tire gauges because I'm a klutz and can't get the danged things to seal correctly. As I understand it, you need to press the gauge onto the stem so that the little nipple thing is depressed, BUT air is not leaking out. At that point, the air pressure inside balances against the spring in the gauge and you get a repeatable result. If air is hissing out while you take the reading, you may be getting a somewhat low, somewhat variable result.

 

[Solodays]

Originally posted by: Chaotic42
The tire gauge will report the pressure in your tire. At 20F, that pressure will be lower, with all other things constant, than at 70F. That's just physics.

Your gauge should be in PSI, even if it just says pounds.

You need to check the doors of your vehicles for proper tire pressure. There should be a stucker or metal plate that tells you what to inflate your tires to. Live by that number and check your tire pressure twice per month or more.

You should be able to hold the gauge steady on the stem and get a constant pressure. If not, invest the $.99 in a new pressure gauge. It's very handy and there's no excuse for not having one that works.

yea, i already know what psi it is.

.99 cent for a tire gauge? no thx..i'm thinking of this onehttp://www.drivegreen.com/productkt.shtml

 

[mercanucaribe]

Originally posted by: Solodays

Originally posted by: Chaotic42
The tire gauge will report the pressure in your tire. At 20F, that pressure will be lower, with all other things constant, than at 70F. That's just physics.

Your gauge should be in PSI, even if it just says pounds.

You need to check the doors of your vehicles for proper tire pressure. There should be a stucker or metal plate that tells you what to inflate your tires to. Live by that number and check your tire pressure twice per month or more.

You should be able to hold the gauge steady on the stem and get a constant pressure. If not, invest the $.99 in a new pressure gauge. It's very handy and there's no excuse for not having one that works.

yea, i already know what psi it is.

.99 cent for a tire gauge? no thx..i'm thinking of this onehttp://www.drivegreen.com/productkt.shtml

Why didn't somebody come up with that before? I hate the whole pressing-the-guage-on-the-tire-but-not-all-the-way-and-air-leaking thing, then using a compressor with an inaccurate guage, then not checking pressure with the digital gauge because I don't want to release air...

 

[Itchrelief]

Originally posted by: Solodays

Originally posted by: d33pt
1. when it's cold out, the tire pressure will be a little lower than it should be. not too much though. maybe 1 psi.

yes, i know that when the temperture drops 10 degree you will lose 1 psi, but despite all the cold, will the tire still give an accurate measure using a tire gauge when its super cold out?

4. get a good dial type gauge that holds the pressure until you release it. You push it on the valve hard until air stops leaking out. do not use a pencil type gauge. those are highly inaccurate.

pencil type gauge HIGHLY INACCURATE? what type do you use?

i was thinking of getting this one...http://www.drivegreen.com/productkt.shtml

As long as you take the pressure at the temperature it will be driven at, the reading should be good enough for most people. Most tire gauges aren't laboratory quality anyways.

You could get anal and buy a really expensive tire gauge, but then Murphy's law says that one of these days you'll drop it on the ground and step on it, and kick it across the garage. There goes the accuracy.

I guess maybe a nice gauge would be easier to seal correctly. I can't use a pencil gauge correctly half the time, so I just end up looking at the gauge on the air pump, which isn't that accurate either, but at least I can get a repeatable result out of it.

Anyone with a nice tire gauge know if they're any easier to get a good seal on the stem than with a cheapie?

 

[mercanucaribe]

Originally posted by: Itchrelief

Originally posted by: Solodays

Originally posted by: d33pt
1. when it's cold out, the tire pressure will be a little lower than it should be. not too much though. maybe 1 psi.

yes, i know that when the temperture drops 10 degree you will lose 1 psi, but despite all the cold, will the tire still give an accurate measure using a tire gauge when its super cold out?

4. get a good dial type gauge that holds the pressure until you release it. You push it on the valve hard until air stops leaking out. do not use a pencil type gauge. those are highly inaccurate.

pencil type gauge HIGHLY INACCURATE? what type do you use?

i was thinking of getting this one...http://www.drivegreen.com/productkt.shtml

As long as you take the pressure at the temperature it will be driven at, the reading should be good enough for most people. Most tire gauges aren't laboratory quality anyways.

You could get anal and buy a really expensive tire gauge, but then Murphy's law says that one of these days you'll drop it on the ground and step on it, and kick it across the garage. There goes the accuracy.

I guess maybe a nice gauge would be easier to seal correctly. I can't use a pencil gauge correctly half the time, so I just end up looking at the gauge on the air pump, which isn't that accurate either, but at least I can get a repeatable result out of it.

Anyone with a nice tire gauge know if they're any easier to get a good seal on the stem than with a cheapie?

I have an Accutire, which is supposed to be a "good gauge". It was cheap-- something like $12 at Fry's. The sealing sucks. You really have to do it right or it just loses pressure at like 2psi per second.
I think the only gauge that would be easier to use would be one that clamps on like the nozzle from a tire pump.

 

[Solodays]

[/quote]

As long as you take the pressure at the temperature it will be driven at, the reading should be good enough for most people[/quote]

what you mean by ..pressure at the temperature it will be driven at?

 

[Solodays]

Originally posted by: Itchrelief
3. By any chance is the SUV a Ford Explorer? Ford specified a somewhat low tire pressure for Explorers (most vehicles seem to recommend about 30 psi) for the model years affected by the Firestone tire recall. Crappy tires + already low suggested tire pressure + people letting tire pressure go low = highway alligators.

4. I hate tire gauges because I'm a klutz and can't get the danged things to seal correctly. As I understand it, you need to press the gauge onto the stem so that the little nipple thing is depressed, BUT air is not leaking out. At that point, the air pressure inside balances against the spring in the gauge and you get a repeatable result. If air is hissing out while you take the reading, you may be getting a somewhat low, somewhat variable result.

it's an honda cr-v at 26psi.

 

[d33pt]

Originally posted by: Solodays

Originally posted by: d33pt
1. when it's cold out, the tire pressure will be a little lower than it should be. not too much though. maybe 1 psi.

yes, i know that when the temperture drops 10 degree you will lose 1 psi, but despite all the cold, will the tire still give an accurate measure using a tire gauge when its super cold out?

4. get a good dial type gauge that holds the pressure until you release it. You push it on the valve hard until air stops leaking out. do not use a pencil type gauge. those are highly inaccurate.

pencil type gauge HIGHLY INACCURATE? what type do you use?

i was thinking of getting this one...http://www.drivegreen.com/productkt.shtml

that thing is pretty cool. $25 is not bad if it is accurate. try it out and let me know how it works. i air up/down all the time and it would save me a lot of time. i use an accugage dial type gauge. kinda like this:
http://www.motoworldracing.com/accugage-hose-accessories.html

 

[Sluggo]

The dial type gauges are much easier to use since it will "hold" the reading until you push the button

Expensive example Expensive, but it does allow you to bleed pressure off.

You can generally pick them up for <$20

The pencil ones are crap and basically unuseable.

 

[B00ne]

You dont need a pressure gauge (well maybe in the US you do). Every gas station has pressure gauges at their tire filling stations. And unlike your personal one theirs are tested, calibrated and certified on a yearly basis - you can verify their calibration schedule by the little sticker seals which have to be on those gauges (as well as gas pumps) to proof that they are still valid.

 

[marulee]

Originally posted by: d33pt
1. when it's cold out, the tire pressure will be a little lower than it should be. not too much though. maybe 1 psi.

2. PSI stands for Pounds per Square Inch. So 30 lbs is 30 PSI on your gauge.

3. It all depends on the tire. Go by what the manufacturer recommends on the doorjamb.

4. get a good dial type gauge that holds the pressure until you release it. You push it on the valve hard until air stops leaking out. do not use a pencil type gauge. those are highly inaccurate.

:thumbsup:

 

[Paperdoc]

1. Yes, you get the right answer- it does not matter what temp the tire is. BUT it IS important that you measure ONLY when the tire is cold! The pressure in a tire rises as it warms up, depending on how warm / how much use. The specs on the door sticker are based on measurments of a cold tire only. By that, they mean from a long stop, driven no more than about a mile before measuring. For that reason I often deliberately over-inflate my tires by about 5 psi when they are warm, then wait until next morning. Then I measure each, bleed off a bit of air, and get each down to the recommended cold pressure.

2. Yeah, many gauges say "lb" when the should say "lb per square inch" or "psi".

3. Like many said, look for the sticker on the door or frame. It will tell you the right pressure, and even sometimes different settings depending on which tire size you have.

4. If it leaks while you are reading, it's wrong, so try again. And note the temperature thing - it WILL say something different if your tire has been running for a few miles.