Inflating tires in 15 degree weather

[sdrtile]

My michelin tires call for 110 lbs cold only
I am currently in 15 degree weather and headed to Florida. My pressure is at 96 now. Does it matter what the outside temperature is and when I reach 70 degree weather should I readjust pressure? Should I fill to 110 in the cold?

[ThomB]

Everything I've ever about airing the tires has me doing it before any heat can hit the tires (including much in the way of sun).
I personally run my tires in the 88lb range and they will heat up to about 108 on the rear and just under 100 on the fronts after about 15 minutes on the road.

[Podivin]

It's cold inflation for where you are, not for where you're going.
Besides, the temp swing is really THAT big so no worry of over inflating a tire (you can always check them again tomorrow).
If you start out at 96 you'll be under inflated and more at risk of a blowout.

So set them to 110 and have a nice trip!

[Cooperhawk]

If on a cold morning my tires read above 90 psi I leave them alone. In twenty miles they will be at 110 or higher.

They really should show a chart for colder temps. My 90 psi will be over 100 when I check in the morning and it's now 70 outside.

[70ChevelleSS]

Is 110 psi the MAX COLD inflation pressure stamped on the sidewall or the cold inflation pressure from the Michelin charts based on weight? Always use the charts Michelin provides. Cold inflation pressure means cold, not what it will be later after driving or the sun beating on them, etc. Too many variables to provide hot pressures that's why they always provide cold pressures. They know the pressure will rise after driving and they've taken that into consideration so fill the tires the way they say. As you travel south check and adjust each morning.

[al1florida]

While, yes the inflation pressure is for "cold" tires. The cold tire meant that you should check you tires before driving, not after going 50 miles at 65mph so you have hot tires. At the same time, after driving for 50 miles at highway speeds you don't want to deflate your tires.

Now as far as your tire temp at 96psi with the temp at 15 degrees and you are heading south.......

First question, have you weighed your rig so you know how much weight you have on each tire? If not, then you have no idea what your tire pressure should be, and you should run your tires at what is on the sidewall, which is 110psi.

Second question, do you have a TPMS (Tire Pressure Monitor System)? If not you are in far more danger of having a slow leak as you drive and having a blow out or damaging a tire, than you are about worrying about 96psi at 15 degree temp.

If you have weighed your rig and determined that your tire pressure should be say 105. Then, especially heading south, I would not go through the trouble to inflate from 96 to 105, only to deflate your tires in a day or two in warmer weather.

The key thing which damages tires is heat, primarily from under inflation. Driving in 15-45 degree weather at your starting pressure of 96psi is not going to damage your tires.

Personally I inflate my tires to the proper pressure at about 70 degrees. The proper pressure determined from weighting my rig. If it is cold and the pressure drops by 10-15 degrees, I do not inflate, unless I am going to continuously travel it that cold of weather.

[al1florida]

It does seem like this discussion about should I increase the tire pressure since the temp is 15 degrees, would mean that since the temp in the afternoon will be 60 degrees or even higher, then I should stop, let the tires cool and the deflate to the proper pressure, then the next morning at 20 degrees re-inflate the tires.

Additionally as what happens in desert climates my morning temp is 25 degrees and my afternoon temp is 75. What am I supposed to do change the pressure twice a day.

Use some common sense. You don't want the pressure at any extreme, either high or low.

[gnewhall]

As Al1florida said you should weigh your rig (4 corners if possible) then go online to the tire mfgs charts and adjust your tires to the recommended pressures for your weights. My 2013 Adventure 37F pressures are 80psi in front and 90psi in the rears.

[Wayne M]

Weighing the 4 corners is the preferred method of determining weight distribution and tire pressures. Just remember the what ever the higher weight rating across the axle the higher weight is what is used to determine air pressure.

Going from 15˚F to 70˚F will increase the pressure by 5.61 pounds. For every 10 degrees of temperature change their will be a 2 percent change in PSI. Your tires at 70˚ would be 101.6 psi.

If you know what your weight is, set a fudge factor on your tire pressure. Let us assume that your weight requires a PSI of 100. If you set your tire pressure to 105 and drop 5 psi you are still within your minimum pressure for the load of 100 psi. if it increase 5 psi you are still under your max load capacity of 110 psi.

If you or your passenger gains weight, well all bets are off.

For every 10 degrees of temperature change there is a 2% change in PSI.
For every 1000 feet of elevation there is approximately .47 psi difference.

So if we were to assume that you were at 5000 feet and dropped to sea level pressure starting out at 100 psi would be 102.5 psi (give or take a few tenths) and if you were at sea level with 100 psi and went up to 5000 feet the tire pressure would read 97.5 psi

But it doesn't end there.
If the temperature increased from 15˚F to 70˚F there would be a 2% psi increase for each 10 degrees of temperature change.
So, 100 psi at 15˚ and temperature goes up to 25˚ there is a 2% change = 102 psi
102 psi and temperature change to 35˚ = 104 psi
104 psi and temperature change to 45˚ = 106 psi
106 psi and temperature change to 55˚ = 108 psi
108 psi and temperature change to 65˚ = 110 psi
110 psi and temperature change to 70˚ = 112 psi

Compounded with the 2.5 psi change because of altitude decrease the
PSI would be 114.5 and adjustments would have to be made at cold tire temperature to bring the pressure back into the recommended range.

===========================
A ponder: If tire pressure changes at 2% for every 10 degrees of temperature, than 70-15=55 degrees of change. Then 2% for every 10 degrees would be approx. 8.5% and that would be 108 psi going from 15˚ to 70˚, or is it exponential as above with every 10 degrees plus 2% added to that 10˚?

[jadatis]

Your pressure advice is all about not overheating any part of rubber of tire.
Cold means when inside tiretemp= outside tiretemp
Advice is given for 18 degrC/65degrF.
When colder outside , cooling down of rubber is better, because of larger temp-differences, an d when hotter then 65degrF the other way around.
My estimation is that if you filled advice at 65 degr, the cooling down/ warming up is in balance , so rubber stays below critical temp, between outside 30degrF and 100degr F.

[jerichorick]

Originally Posted by sdrtile

My michelin tires call for 110 lbs cold only
I am currently in 15 degree weather and headed to Florida. My pressure is at 96 now. Does it matter what the outside temperature is and when I reach 70 degree weather should I readjust pressure? Should I fill to 110 in the cold?

ALWAYS set your tire pressure at the coldest part of the day, with no sun on the tires.. When traveling, I check the pressure each morning before I head out if the ambient temperature has changed more than 5* average. If I need to let air out I do. I carry a 150psi compressor to charge the tires when needed.


How old are your tires? Have you had a 4 corner weigh lately?



I will not run tires at max load. My coach had 110psi max tires and the "door tag" called for 110psi. We bought used. The date code was good but the tires were starting to show sidewall checking. After a 4 corner weigh I realized we were heavy and pushing the tires to the max. I went to Toyo M154 H rated that have a 120psi max cold rating and a better load rating. Best move I could have made. They ride better and run cooler. Much less $ than Michelin.