russianDude

Today morning it was around 20F, and I was crazzy enough to measure my tire pressure. It seemed low ( 2.8psi ). And 3 weeks ago it was 3.2psi.
Question: is it because of the cold weather??
What is the right way to measure tire pressure? I know that car needs to be rested for a while before you mesure tire pressure, but what about very cold temperatures.... ?

mrdeeno

i think about every 10 degrees F below the temp you measured at before, it'll be about 1 psi lower. was the last time you checked around 60F?

the 32psi specified is for cold tire pressure (3-4 hrs not driving) and i think it's normal room temperature which i don't know what the value they use is, probably around 70F. so if it's that cold out and you expect it to stay pretty cold for awhile, then adjust it for 32psi to maintain that cold tire pressure, otherwise you'd be underinflated (assuming it's staying around 15-20F).

but when it warms up again, you gotta checked and adjust again unless you want to be overinflated.

russianDude

Yeah, last time I checked was around 60s, I think you are right that pressure drops for lower temperature... Its obvious from physics, but I thought that there should be no such noticable difference....
I think I need to put 32ps when it is like 30-40F.... and change it spring when it is like 60.
the weather here is crazzy, one day it is like 60, another day its 20F.... I can't keep up re-configuring my tire pressure

SILVERADO

check the pressure first thing in the morning when the tires are cold. note how much air needs to be put in each tire. go to gas station and add air. or add 4 or 5 pounds when you get gas, then next morning check pressure and let air out to desired pressure. plan on adding air as the weather is getting colder. each 10 degree decrease in temperature = 1 pound of air pressure.

acura_service

Your tires support the weight of your vehicle, right? Well, they don’t! It’s the air pressure inside them that actually supports the weight. Maintaining sufficient air pressure is required if your tires are to provide all of the handling, traction and durability of which they are capable.

However, you can't set tire pressure...and then forget about it! Tire pressure has to be checked periodically to assure that the influences of time, changes in ambient temperatures or that a small tread puncture has caused it to change.

The tire pressure recommended in your vehicle's owner's manual or tire information placard is the vehicle’s recommended "cold" tire inflation pressure. This means that it should be checked in the morning before you drive more than a few miles, or before rising ambient temperatures or the sun’s radiant heat affects it.

Since air is a gas, it expands when heated and contracts when cooled. In most parts of North America, this makes fall and early winter months the most critical times to check inflation pressures...days are getting shorter...ambient temperatures are getting colder...and your tires' inflation pressure is going down!

The rule of thumb is for every 10° Fahrenheit change in air temperature, your tire's inflation pressure will change by about 1 psi (up with higher temperatures and down with lower).

In most parts of North America, the difference between average summer and winter temperatures is about -50° Fahrenheit...which results in a potential "loss" of about 5 psi as winter’s temperatures set in. And a 5 psi "loss" is enough to sacrifice handling, traction, and durability!

Additionally, the difference between cold nighttime temperatures and hot daytime temperatures in most parts of the country is about 20° Fahrenheit. This means that after setting tire pressures first thing in the morning, the vehicle’s tire pressures will be almost 2 psi higher when measured in the afternoon (if the vehicle was parked in the shade). While that is expected, the problem is when you set your vehicle’s tire pressures in the heat of the day, their cold pressures will probably be 2 psi low the following morning.

And finally, if the vehicle is parked in the sun, the sun’s radiant heat will artificially and temporarily increase tire pressures.

PRESSURE LOSS:

While a tire is carefully designed to contain air, some air leaks out. Air leakage can occur overtime through the tire itself, though the valve core and at the rim. Typically, leakage results in loss of about 1 psi inflation per month. At that rate it won’t take long for a tire to become excessively under-inflated.

Undetected punctures, bruise damage, cuts, and rim/valve damage may produce more rapid air loss. Under-inflated tires in general and performance radials in particular, may not convey a message of under-inflation to the driver until heat failure or rim dislodgment occurs. Therefor, cold inflation pressures must be checked as often as possible. Consult your vehicle’s Owners Manual or Tire Placard for the proper inflation for your tires.

aciurczak

I check my tire pressure regularly, and had always set it at 36F, 32R. However, I just purchased a new tire gauge to replace my 7-8 year old one that seemed to be leaking a bit. Turns out my gauge has been reading 3-4 psi low. My tires were actually at 32F,29R. I pumped them back up to 36/32 with the more accurate gauge, and I'll see if I prefer it like this....

If folks want a reasonable priced, decent quality digital gauge, check out http://www.roadgear.com/accessor.html .

vince

3.2 PSI? Are you sure that's not in bar's?

bioyuki

I'm sure he meant 32 psi. 1 bar = somewhere around 15psi I think.