tire pressure

[kejy]

I adjusted my tire pressure to 98 psi which matches to my weight. As I drive the temp. in the tires go up and so does the pressure went as high as 104 psi so do I lower my pressure so when it gets hot it is correct or does it matter if it goes higher. Thanks this is a great site. Ken

[Tha_Rooster]

You always adjust tire pressures cold, as you drive your tires heat up and pressures go up also. If your tires are low they heat up faster and hotter which is one of the causes of blow outs.

[GaryKD]

Hi kejy,
Always make the correct PSI when the tires are cold. Any PSI increase due to driving has already been taken into consideration by the tire manufacturer. If you are looking at a TPMS measurement there is another item that you will notice. While driving, tires on the sunny side of the coach will get hotter than tires on the shady side. This is a piece of data that, while interesting, can be ignored.

[Crasher]

Also, a good rule to follow, is to carry 5 psi higher than what the chart says for your tire load. This will give an extra margin of safety for keeping above the minimum, but will also cover you when you start out on a very cold morning. Minimum tire pressures are generally set at 60*F. Also as mentioned, the temp reading of the TPMS is useless while moving, as the external sensors are being moderated by the OAT air. Only after you are parked for 15-20 minutes will they give you an accurate temp reading.

[Steve Ownby]

Originally Posted by Crasher

Also, a good rule to follow, is to carry 5 psi higher than what the chart says for your tire load. This will give an extra margin of safety for keeping above the minimum, but will also cover you when you start out on a very cold morning. Minimum tire pressures are generally set at 60*F. Also as mentioned, the temp reading of the TPMS is useless while moving, as the external sensors are being moderated by the OAT air. Only after you are parked for 15-20 minutes will they give you an accurate temp reading.

Great post Crasher! I'm an advocate of inflating 5-10 psi over the minimum but had not really considered the temp part of the equation.


Steve Ownby
Full time since '07

[flynnwalter]

Crasher
Might seem counterintuitive, but as I understand it, an inanimate object such as a tire pressure monitor is not susceptible to 'wind chill'. It would only cool down faster to a lower outside temperature when driving than if parked. But it would still reflect the actual temperature at the monitor. Systems that monitor the inside of the tires would be more accurate, but neither one is affected by wind chill.

NWS Wind Chill Questions and Answers


Not sure what you mean by OAT air? Is it something other than wind chill? Thanks.
Frank W. 09 Cayman
Lake City, Florida

[flynnwalter]

All
Recently did a lot of research before buying new tires two sizes larger than our OEMs. I doubt anyone could find a subject that has much more research done than truck tires. There are lots of trucks and they use lots of tires each year and companies want every edge to cut costs. While I, too, am guilty of leaving some 'wiggle' room in my guestimates, I don't believe extra psi is necessary considering all the educated as well as experienced talent employed by tire companies. They have already built in their 'fudge' factors. Further, adding extra psi when starting out in the cold to compensate for driving into warm areas is also probably a bad idea. The tires warm up very quickly once driven and then you have tires inflated more than necessary. This can be dangerous especially in rain.
Frank W. 09 Cayman
Lake City, Florida