checking air pressure in tires...help...

Anghang

Platinum Member
Apr 30, 2001
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i've never had to really do it, all cars i've driven were always rentals...

but now that i own a car...how do i go about checking the air pressure in the tires?...i mean, i see on the side of the tire it says P265/70R15...i've got no idea what that means...and i do have one of those cheap tire air pressure guage things where you stick it into the air slot and a measurements pops up...usually between 25-30...what does the 25 to 30 signify? what would be the optimal measurement for the tires to be at?

of course i'm only worrying about this now being that i notice that when i let the steering wheel go, my car tends to go to the right... :(

 

Platypus

Lifer
Apr 26, 2001
31,046
321
136
You need to get a guage reader, which you push onto the air socket of your tire. It will tell you PPI, pressure per inch of your tire.
Open your passenger, or driver side door, and it will tell you the recommended pressure on the side of the door hing. It varies with every car.
 

Jerboy

Banned
Oct 27, 2001
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<< i've never had to really do it, all cars i've driven were always rentals...

but now that i own a car...how do i go about checking the air pressure in the tires?...i mean, i see on the side of the tire it says P265/70R15...i've got no idea what that means...and i do have one of those cheap tire air pressure guage things where you stick it into the air slot and a measurements pops up...usually between 25-30...what does the 25 to 30 signify? what would be the optimal measurement for the tires to be at?

of course i'm only worrying about this now being that i notice that when i let the steering wheel go, my car tends to go to the right... :(
>>



I recommend you buy a dial style gauge that locks in the reading. The "popping boner" style readers are real pain in the a$$ to use.

The optimal pressure for the tire should be listed on the door jamb. You need to take measurement before the car has been driven for the day. Deflate/inflate to whatever is on the door jamb and you should be fine. five PSI makes quite a difference.
 

pyonir

Lifer
Dec 18, 2001
40,856
321
126
it should say on the side of the tire what PSI you need them to be or it recommends that they be at. normal is usually anywhere from 25-35psi on most car tires. just make sure all the tires are at the same psi. on the side of the tire should say something in () like (recommended 35psi).
 
Oct 9, 1999
15,216
3
81
actually it varies per tire size. If you get lower profile tires it varies from stock OEM tires.

Now your tire should have some marking for it. I know my bike's tire does and so does my car's tire.

In general 32/32 is what we keep it at. 32 front, 32 rear tires.

 

Evadman

Administrator Emeritus<br>Elite Member
Feb 18, 2001
30,990
5
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Bah, mine are set for 50 PSI. Offroading they go to 8 :)
 

Jerboy

Banned
Oct 27, 2001
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<< it should say on the side of the tire what PSI you need them to be or it recommends that they be at. normal is usually anywhere from 25-35psi on most car tires.



<< just make sure all the tires are at the same psi. on the side of the tire should say something in () like (recommended 35psi). >>

>>



Rule of thumb is you get better mileage with higher pressure and softer ride with slightly less pressure. Over-inflation causes the center of the tires to wear out and under-inflation causes the sides to wear out. Your best bet is to inflate it exactly to what's written on the door jamb.

Pyonir, some cars have different pressure requirements for rear and front. A more correct statement is make sure right and left tires have the same pressure.

Take a measurement again after a week on all wheels. They should all be the same. If one or more tire isn't, you have a leak.


 

Anghang

Platinum Member
Apr 30, 2001
2,853
0
71
awesome!...i checked out the door jamb and got the measurement...should be 26psi...
thanx guys...i knew i can count on ATOT...love this board!!! :D
 

etech

Lifer
Oct 9, 1999
10,597
0
0
The maxium pressure recommend for the tire is listed on them. That is not what they should be run at in most cases.

 

Tominator

Diamond Member
Oct 9, 1999
9,559
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Only check them when they've sat for over 12 hours.....Air expands with heat and would read at a higher pressure if warm.
 

wyvrn

Lifer
Feb 15, 2000
10,074
0
0
The pressure on my wife's tires says 44psi max, so I put em at 35. Damn I have never seen 44 on a tire before.
 

Squisher

Lifer
Aug 17, 2000
21,204
66
91
Jerboy's got it right, you need the Car manufacturer's recomended pressure, not the max. psi from the sidewall. You should check tire pressure once a month. Incorrect or uneven pressure is a safety hazard. Check pressure before you drive the car a great distance, when tires get hot the air expands and gives higher readings then what is really there. Do not de-inflate tires because of this higher reading.
 

creedog

Golden Member
Nov 15, 1999
1,732
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i'd go with what is on the tire, not what is in the door jamb. You probably do not/will not always have the exact same tires on you car that they came from the factory with.

id say most tires are good at 28-32, lower profile tires 38-44 psi
 

LoneWolf1

Golden Member
Jun 16, 2001
1,159
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<< i've never had to really do it, all cars i've driven were always rentals...

but now that i own a car...how do i go about checking the air pressure in the tires?...i mean, i see on the side of the tire it says P265/70R15...i've got no idea what that means...and i do have one of those cheap tire air pressure guage things where you stick it into the air slot and a measurements pops up...usually between 25-30...what does the 25 to 30 signify? what would be the optimal measurement for the tires to be at?

of course i'm only worrying about this now being that i notice that when i let the steering wheel go, my car tends to go to the right... :(
>>

First off, P265/70R15 is the size of the tire.
  • P = passenger tire.
  • 265 = the width of the tread on the tire in mm.
  • 70 is known as the aspect ratio. the height of the tire is ~70% of the width (265mm)
  • R simply means that it is a radial ply tire. The cords, which can vary in material with the brand and tire speed rating, are running in an X pattern to the profile of the tire.
  • 15 is the diameter of the wheel(rim) in inches that the tire is made to fit on.
In the tire shop that I work at, we generally set the tire pressure at 32psi(cold) for most cars, 35psi(cold) for others.

As far as your car going to the right, if it's not due to low pressure in the right front tire, you might want to have the alignment checked.

hope this helps some.
 

Tominator

Diamond Member
Oct 9, 1999
9,559
1
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<< As far as your car going to the right, if it's not due to low pressure in the right front tire, >>



True, but most roads are built with a 'crown' to get rid of water. Wind will cause a car to have the sensation of pulling.

Check your air pressure every 2 weeks and when tires are cold.

ALWAYS use the recommened air pressure found on the door jamb, in the glove box or in the owner's manual.

Get an alignment every 2 years at the minimum and any time you buy new tires. Rotate every year.

NEVER trust the guages on those little air pumps you plug into the lighter! Buy a quality air guage but be aware, they can be wrong even though you bought a good one!



<< I recommend you buy a dial style gauge that locks in the reading. The "popping boner" style readers are real pain in the a$$ to use. >>



Unless you are going to spend 30 to 40 bucks for a dial type, those 'popping boner' ones are much more accurate!