Tire inflation in the cold weather?

[bigdob24]

Stuck in Joplin MO thanks to the big storm "Goliath"
I have a TPMS on the RV and when I left home a comfortable 55 degrees the tires were all inflated around
102
Now the temps here are below freezing around 28 or so at night and just above freezing in the day.
We don't plan on traveling to Lawton through Ok City until tomorrow when roads will be in good shape.
Today I turned on my TPMS and it alarmed due to low pressure , they were around 94 or so.
This is not due to leaks just cold weather.
How do you handle cold weather tire inflation ? Leave it or adjust?
Im guessing to leave it alone as it will be higher when temps go up.
Thanks
Dan

 

[Garypowell]

I am very mindful of tire pressure and have a scale chart for above and below 70 degrees. But for the tires to naturally drop due to cold means they are still properly inflated for the load you first inflated them for. As long as you can account for the drop in pressure is due to a drop in temperature you are OK.

Your other problem I have faced too. If I don't think it will take long for the tires to come up past the alarm point then I just don't turn it on until they are. But you can always set a new alarm point and then reset it later too.

 

[bigdob24]

Thanks Gary
Thats what I thought but always open to opinions.
Im sure the drop in pressure is due to the cold temps.
I will shut the monitor down until I get the tires warmed up and then turn it on and see where I'm at.
Dan

- - - Updated - - -

Gary
Any way you can post the chart you use?

 

[jmgratz]

It depends on how much it will warm up during the day. If the morning temp is 30 degrees and it will only get to 38 then you probably will need to add air to the tire. If the them will warm up to 60 then maybe not. If you don't add air when it is cold you will be running your tire underinflated which is really not good for the tire.

 

[bigdob24]

I left this morning at 28 degrees. Tires were around 96.
I went about 10 miles and they were up to 104 or so and ended up around 114 when they warmed completely.
Funny how that works
So they will recover to the original setting , don't add air to cold tires
Dan

 

[dlw930]

Rated maximum tire pressures are based on cold pressure first thing in the morning before the sun or travel increases the pressure. Pressure will increase about 2% for every 10 degrees increase in ambient and/or air pressure within the tire. My tires are rated at 110 psi so for carrying the proper load, they should be inflated to 110 psi cold regardless of whether it's summer or winter. When towing, road friction and increasing ambient temperature typically increase the pressure 10-15 degrees.


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[Garypowell]

Dlw.....you are correct to put 110 in your tires but only if they are at 70 degrees. You are correct it does not matter if 70 deg in tx in the winter or 70 deg in Alaska in the summer. But it is the temperature of the tire that is the key thing.

 

[jmgratz]

Ok , is there any tire engineers out there? I would venture to say if it is 35 degree outside and your tire has 90 psi with it stamped 110 psi cold you are under-inflated. Am I right. I know I would at least like to be 105 psi to be closer to 110. If it was 110 psi at 70 degrees F wouldn't that be stated on the sidewall? How about if it is 0 F and gets up to 10 F. It would be under-inflated all day. Am I over-thinking this issue?

 

[travelin2]

Ok , is there any tire engineers out there? I would venture to say if it is 35 degree outside and your tire has 90 psi with it stamped 110 psi cold you are under-inflated. Am I right. I know I would at least like to be 105 psi to be closer to 110. If it was 110 psi at 70 degrees F wouldn't that be stated on the sidewall? How about if it is 0 F and gets up to 10 F. It would be under-inflated all day. Am I over-thinking this issue?

I'm no engineer, but I agree with you. If it's winter temperatures and it's going to stay cold and if the air pressure is down 10-15% from maximum pressure I'm adding air to get back to maximum pressure-truck, car, trailer.
If it's 35* and the tire was properly inflated yesterday and it's going back up to 70* later in the day, I'm good to go.


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[JanAndBill]

Tire manufacturers recommend adjusting air pressure based on the ambient temperature and in some cases altitude while the tire is cold (tire has been allowed to acclimate at least 3 hours). See this article from Bridgestone http://www.bridgestonetrucktires.com/publications/02v7iss1/ra8.asp

 

[Lou_and_Bette]

Durning the 3 years I spent in Fairbanks, Alaska, we needed to adjust tire pressure after the first drop in really cold weather and again when the temperature went up significantly. There were cases after the temperature dropped to less than 30 below tires would lose so much pressure, tires would lose their bead seal when trying to drive on them and go completely flat. We called it "adding winter air."

 

[EPaulikonis]

I'd much prefer to be overly curious is better than ignorant on the matter Jim. Bridgestone has a good summary of the topic here. The max pressure at 70F while tire is "cold" is misleading. The tire needs to be at the same pressure (let's say 80psi) if it's 70 or 32 outside. What's really important is to have the internal tire temperature at the same temperature as the external air temperature, whether it's 70F or 32F...that's what "cold" really means, when checking pressure.

Our HD tires (80-100psi) on towing rigs and trailers will have a +/- of ~2psi for each 10F of temperature variation. Remember, cold inflation refers to the internal tire air temperature compared to the outside air temp. If it's 32 outside and you're parked in a heated garage (say 60F), you'll need to do some math; add ~6 psi over pressure you want (86 psi to keep tracking to our 80psi from above) to compensate for the 28F temperature drop outside. If you don't compensate and add the 6psi in the garage, the internal tire temp will drop when you're outside driving and you'll be operating on under inflated tires.

Altitude isn't nearly as important, but it does need to be considered if you're driving from sea level and spending time in Denver or Cheyenne. There's a good table here to show ambient air pressure change from sea level up to 10,000 feet. The overall change between extreme elevations on the table is only 4.5 psi, so you'd have to add ~2.5 psi to your tires based on elevation change only if you travelled from the sea shore to Denver in a single day.

So to your question, if it's 35F outside and you're at 90psi, you're under inflated for a 110 "cold" psi tire. If it's going to stay at 35 (or even a daytime high of 50; our tire psi would go up by ~3psi according to the 2% equation), fill the tire to 110psi at 35F. Most pressure gages used are only accurate within +/- 2psi anyway, so the 15F temperature increase is negligible.

If you happen to travel to Key West FL that same day and temps reach 80F, let the tire rest for 3 hours and then check the pressures. You will re-set them when cold (matching 80F ambient temperatures) for Key West temperatures to 110 psi. The Bridgestone page talks this specifically under What should we do then? paragraph.

Ok , is there any tire engineers out there? I would venture to say if it is 35 degree outside and your tire has 90 psi with it stamped 110 psi cold you are under-inflated. Am I right. I know I would at least like to be 105 psi to be closer to 110. If it was 110 psi at 70 degrees F wouldn't that be stated on the sidewall? How about if it is 0 F and gets up to 10 F. It would be under-inflated all day. Am I over-thinking this issue?

 

[jmgratz]

I'd much prefer to be overly curious is better than ignorant on the matter Jim. Bridgestone has a good summary of the topic here. The max pressure at 70F while tire is "cold" is misleading. The tire needs to be at the same pressure (let's say 80psi) if it's 70 or 32 outside. What's really important is to have the internal tire temperature at the same temperature as the external air temperature, whether it's 70F or 32F...that's what "cold" really means, when checking pressure.

Our HD tires (80-100psi) on towing rigs and trailers will have a +/- of ~2psi for each 10F of temperature variation. Remember, cold inflation refers to the internal tire air temperature compared to the outside air temp. If it's 32 outside and you're parked in a heated garage (say 60F), you'll need to do some math; add ~6 psi over pressure you want (86 psi to keep tracking to our 80psi from above) to compensate for the 28F temperature drop outside. If you don't compensate and add the 6psi in the garage, the internal tire temp will drop when you're outside driving and you'll be operating on under inflated tires.

Altitude isn't nearly as important, but it does need to be considered if you're driving from sea level and spending time in Denver or Cheyenne. There's a good table here to show ambient air pressure change from sea level up to 10,000 feet. The overall change between extreme elevations on the table is only 4.5 psi, so you'd have to add ~2.5 psi to your tires based on elevation change only if you travelled from the sea shore to Denver in a single day.

So to your question, if it's 35F outside and you're at 90psi, you're under inflated for a 110 "cold" psi tire. If it's going to stay at 35 (or even a daytime high of 50; our tire psi would go up by ~3psi according to the 2% equation), fill the tire to 110psi at 35F. Most pressure gages used are only accurate within +/- 2psi anyway, so the 15F temperature increase is negligible.

If you happen to travel to Key West FL that same day and temps reach 80F, let the tire rest for 3 hours and then check the pressures. You will re-set them when cold (matching 80F ambient temperatures) for Key West temperatures to 110 psi. The Bridgestone page talks this specifically under What should we do then? paragraph.

Great info. Never thought about parking in a heated garage and then driving outside in cold weather. With all what you said it could open up another discussion on the value of Nitrogen to inflate your tires. It is my understanding the ambient temperature does not affect it.

 

[JanAndBill]

The Bridgestone link I posted earlier stresses using the proper inflation for the "load" to maintain the correct sidewall profile based on the load you put on the tire. While 110 psi may be the "max" psi cold, your actual inflation may be less. Most manufacturers publish a chart with the psi ratings/load.

 

[lwmcguire]

Maybe this was covered somewhere in the post, the real deal is how heavy are your tires loaded? If you have a decent safety factor then 10-15 pounds on a 110-125 psig rated tire in cool weather don't mean anything. No need to worry one bit.

If your tires are running on the warm side in cool weather you are either overloaded or under inflated. Very simple and not a big deal to worry about. Easy to monitor and fix unless you need heavier rated tires.

 

[NHCelt]

I am very mindful of tire pressure and have a scale chart for above and below 70 degrees. But for the tires to naturally drop due to cold means they are still properly inflated for the load you first inflated them for. As long as you can account for the drop in pressure is due to a drop in temperature you are OK.

Your other problem I have faced too. If I don't think it will take long for the tires to come up past the alarm point then I just don't turn it on until they are. But you can always set a new alarm point and then reset it later too.

The op would be best suited to adjust his tire pressure based on cold inflation psi for his/location the day of traveling...no traveling = no worries.

Regardless, unless your vehicle is losing weight as temps decrease, you can reach a point where you are under inflated for the sprung load...especially with trailers loaded to their max capacity...not generally an issue during a days travel...but theoretically possible.


Also, FWIW, most people have come to agree that trailer tires be inflated to the max psi listed on the sidewall. Although some have disagreed over the years, the nature of shifting loads and road dynamics (potential overloading) argue against the need for a softer ride in a trailer. Obviously, Motorized rv's are a different animal. Lots of discussion on this, but I will always argue that safety is the primary goal and that there are no safety benefits derived from charting tire pressures on trailers and adjusting based on vehicle weight. If you do chart psi by weight, the best formula of psi based upon weight on heaviest tire plus 25% probably puts you at max psi anyway.

Just my 2$ worth...Celt