cold tire pressure

[big craig]

I will be leaving MN in January and will check my cold tire pressures at temperatures well below zero (-20 to -30F) before leaving for the SW. If I inflate tires to recommended 65 psi (goodyear endurance) I'm worried the pressures would increase to a dangerous level once they heat up on the road. I can certainly check pressures again after a few hours in Iowa and lower the pressure. Does anyone have experience with tire pressure vs ambiant temp?

[phillyg]

Assuming you're not driving straight through, I'd recommend resetting psi cold again the second morning,

[Aussieguy]

as you drive to a warmer area , every couple of days check the pressure just to be safe and not have the worry warts all the time


it's not like you are going to drive from cold to hot in a few hours!

[acadianbob]

I find that I have to bleed my tires (MN to Arizona) in about Missouri. Otherwise, my tire pressure monitors go off (for high pressure). I often have to put air back in on the way back to MN. Ambient air temperature makes a substantial difference.

[5picker]

In all my years I've not seen "substantial" differences in ambient tire pressures from hot to cold or vice versa. A few pounds... yes but not substantial. Sitting in the direct sun... that's a different conversation.

Just last week it was in the 70ºs here and this week in the teens. Our tires are not all flat because of a 50º+ drop in temperature. Certainly those who run on the edge of the TPMS alerting have to add a pound or possibly two but again, nothing major.

I would simply check them once you get to a warmer climate and if the pressures are not to your liking, set them accordingly.

[big craig]

Thanks everyone for the advice, my neighbor also suggested to have nitrogen installed. He claims it doesn't expand or contract as much with temperature. I will check pressures every pretrip.

[5picker]

Nitrogen in R/V tires is mostly a sales gimmick and not necessary.

Is nitrogen necessary in "some" tires... yes racing and aviation come to mind but not R/V applications. Unless you can get it done VERY inexpensively, don't waste your money.

Besides regular old air is already 78% Nitrogen!

[BehindBars]

Originally Posted by big craig

Thanks everyone for the advice, my neighbor also suggested to have nitrogen installed. He claims it doesn't expand or contract as much with temperature. I will check pressures every pretrip.

Well, you probably already have about 78% nitrogen in the tires, so for RV purposes, that’s close enough.

[ppine]

With current fuel prices it makes sense to adjust tire pressure with the seasons.
Tire monitoring makes it easy.

[NavyLCDR]

Originally Posted by big craig

Thanks everyone for the advice, my neighbor also suggested to have nitrogen installed. He claims it doesn't expand or contract as much with temperature. I will check pressures every pretrip.

Sure. You just have to find a tire shop that can actually exchange 100% of the air in the tires with nitrogen. And then you also have to carry a nitrogen bottle with you to add nitrogen to the tires as necessary. Please ask your neighbor where they found the facility to exchange the air for nitrogen and ask how big of a nitrogen bottle they have to add nitrogen as needed to the tires.

Nitrogen is 99% sales gimmick and 1% practical use in RV tires.

[Aussieguy]

I think it works ... never got a low tire when was on Nitrogen
come to think of it ... never had my tires go flat on normal air either

[D W]

Originally Posted by big craig

Thanks everyone for the advice, my neighbor also suggested to have nitrogen installed. He claims it doesn't expand or contract as much with temperature. I will check pressures every pretrip.

Nitrogen has it's purpose in aviation, but in every day surface travel it's Snake Oil.

[jimmarako]

Originally Posted by D W

Nitrogen has it's purpose in aviation, but in every day surface travel it's Snake Oil.

Does it have to do with Nitrogen not supporting combustion?

Jim M.

[D W]

Originally Posted by jimmarako

Does it have to do with Nitrogen not supporting combustion?

Jim M.

Yes, by preventing the propagation of a landing gear fire on a blow out, and for its stability at extreme altitudes.

[2witzmans]

We're from MN too. We left 3 wks ago. But prior years we always filled air like always. No problem. Safe trvls

[gw1800]

Normal air is 78% nitrogen. Unless the tire shop pulls a vacuum on the tires, you will not get 100% nitrogen in the tires. Probably closer to90%.
As said, check the tires when you get into the warmer areas. It's easy to let some air out.

[TitanMike]

Originally Posted by gw1800

Normal air is 78% nitrogen. Unless the tire shop pulls a vacuum on the tires, you will not get 100% nitrogen in the tires. Probably closer to90%.
As said, check the tires when you get into the warmer areas. It's easy to let some air out.

Just don't do that on a hot tire.

Only adjust tire pressures first thing, before starting a trip, or after the vehicle hasn't been driven for several hours.

OR

Install a TPMS system that will show your tire pressures before starting driving and warn you of a tire loosing pressure during your driving.

[NavyLCDR]

Originally Posted by TitanMike

Just don't do that on a hot tire.

Only adjust tire pressures first thing, before starting a trip, or after the vehicle hasn't been driven for several hours.

OR

Install a TPMS system that will show your tire pressures before starting driving and warn you of a tire loosing pressure during your driving.

110% agree! I run 65 PSI in the morning and they might hit 80 PSI on the interstate.

[jadatis]

First, you dont need to be worried about the high pressure itself, new tires have test-standards, so they must stand a 2 times the reference-pressure ( yours 80 psi, 160psi).
If half of that is left for an old undamaged tire, its stil 120 psi.
Only anoing is the TMPS alarm going off, but that is a secundary problem wich you then can ignore.

Second, you could considder giving tire a lower pressure when - 20 degr.
To prevent overheating of tire material, wich is the main goal of pressure determination, at colder temperature the tire produces more heat, because of more deflection, but also cooling down is better, because of the more temperature differences between tire material and in and outside tire air.
And yes, more fuel consumption, but I think still no snakebites.

For offroading they lower the pressure even more, at higher ambiënt temperature. But then the used speed is lower.

On the other hand, if 100degrF outside, you certainly must not lower the cold pressure, even if above reference. Then lesser temperature differences between tire material and in and outside tire air, so lesser cooling down.
Then the lesser deflection the higher pressure gives, gives lesser heatproduction, so compensates the lesser cooling down.



You have to find the sweet spot yourselfes, but all I wrote can give you a handle.

Made a list for the relation between the temperature in the tire, and the pressure change, will give it at the end.

You can also use it for checking the cold pressure, because then temp in tire= temp outside the tire.

Use the list like this.
Look up the pressure you determined to be needed, in the list. Behind it the degrF /1 psi pressure change, and write it down or remember it.

List assumed cold pressure to be filled at 70 degrF, but if you use it for 60 degrF, it wont give dramatic differences.

So if - 20 degrF outside, is 80 degrF colder then 60 degrF.
Devide that by the degrF/psi, and you find howmuch lower you can fill safely to prevent overheating.
If you are scared to go that low ( for riding quality or fuel saving) take something in the middle.

But can also use it the other way around.
External tmps sensors give pretty exact temperature at the end of the valve, and not of tire inside air or whatever gascompound.
Then you can calculate, even by head acurate enaugh, what the temperature of the gascompound in the tire is.

Then if 80 psi filled and determined filled at - 20 degr F, it will rise to ( 90--20)/5.5 is 20 psi more so 100 psi, but then lesser heatproduction because if lesser deflection, so warm pressure will not rise that much as when 80 psi cold at 90 degrF.
Already less acurate calc
Better is, you can fill if 80 psi is determined, a 20 psi lower pressure is 60 psi, only for heatproduction.
So if you then use 70 psi in the middle, you are always safe, and high pressure alarm mayby wont go off.

And using lower speed also gives lesser heatproduction.

Here the list.

70degrF./degrF/psi


26 psi/ 13 F/psi
27 psi/ 12,5 F/psi
28 psi/ 12,5 F/psi
29 psi/ 12 F/psi
30 psi/ 12 F/psi
31 psi/ 11,5 F/psi
32 psi/ 11,5 F/psi
33 psi/ 11 F/psi
34 psi/ 11 F/psi
35 psi/ 10,5 F/psi
36 psi/ 10,5 F/psi
37 psi/ 10 F/psi
39 psi/ 10 F/ps
40 psi/ 9,5 F/psi
42 psi/ 9,5 F/psi
43 psi/ 9 F/psi
45 psi/ 9 F/psi
46 psi/ 8,5 F/psi
49 psi/ 8,5 F/psi
50 psi/ 8 F/psi
53 psi/ 8 F/psi
54 psi/ 7,5 F/psi
58 psi/ 7,5 F/psi
59 psi/ 7 F/psi
63 psi/ 7 F/psi
64 psi/ 6,5 F/psi
70 psi/ 6,5 F/psi
71 psi/ 6 F/psi
77 psi/ 6 F/psi
78 psi/ 5,5 F/psi
86 psi/ 5,5 F/psi
87 psi/ 5 F/psi
96 psi/ 5 F/psi
97 psi/ 4,5 F/psi
109 psi/ 4,5 F/psi
110 psi/ 4 F/psi
126 psi/ 4 F/psi
127 psi/ 3,5 F/psi
148 psi/ 3,5 F/psi
149 psi/ 3 F/psi
177 psi/ 3 F/psi

[NavyLCDR]

I prefer the K.I.S.S. principal. If the TPMS show 65 +/- 3 psi in the morning before rolling then I go. During the day as long as all the tires show within 3 to 4 PSI of each other and stay over 62 PSI, I don't worry about it. To me it isn't that difficult.