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"Cold" tire pressure question

ezgoin
Explorer
Explorer
During the Arizona summer my cold tire pressure reads about 5 lbs ABOVE my normal 85 lb desired cold pressure before driving. Should I let 5 lbs of pressure out before hitting the road in extreme heat? If I do, will I be under inflated when I arrive at a cooler location?
The older I get....the better I was.

Bill & Terry
And our canine kids, Skippy & Peanut
2014 Fleetwood Bounder Classic 30T
2016 Jeep Wrangler Unlimited Toad
8 REPLIES 8

jadatis
Explorer
Explorer
Old-Biscuit wrote:
See what I mean.......:B

Not racing just RVng.

Don't make it complicated cause it isn't


Travel day...
Check psi ---adjust up/down....drive

Next travel day----repeat

I also could have written , 'no problem , but my answer explaines
why.

phillyg
Explorer II
Explorer II
Tire mfgrs. state cold means before you start driving no matter what the outside temps are.
--2005 Ford F350 Lariat Crewcab 6.0, 4x4, 3.73 rear
--2016 Montana 3711FL, 40'
--2014 Wildcat 327CK, 38' SOLD

Old-Biscuit
Explorer II
Explorer II
See what I mean.......:B

Not racing just RVng.

Don't make it complicated cause it isn't


Travel day...
Check psi ---adjust up/down....drive

Next travel day----repeat
Is it time for your medication or mine?


2007 DODGE 3500 QC SRW 5.9L CTD In-Bed 'quiet gen'
2007 HitchHiker II 32.5 UKTG 2000W Xantex Inverter
US NAVY------USS Decatur DDG31

jadatis
Explorer
Explorer
Adviced cold pressure is calculated by the vehicle maker for 65degr F /18 degr C.
Then the warming up of rubber of tire is in balance with cooling down of that rubber so the rubber wont go above a sertain temp at wich its hardens and so damages in next bendings of it by the deflection of tire. This is the goal of all pressure calculation.

When its warmer outside the temperature differences are smaller but also the higher pressure inside gives lesser deflection so lesser heatproduction. And the other way around when its colder outside.

My estimation is that if you take car of advice pressure calculated back to 65 deg F , the tires wont overheat in a temperature range up to 110 degr F .

So at higher ambiรซnt temp you need higher pressure.

Will give tabel for that .
Use it like this.
Look up the determined advice pressure in the line with 65 degr F , is fatt printed. Then go in that row to the ambiรซnt temperature you measure the pressure cold ( when inside tire temp= outside tire temp, that simple) Then see what you have to fill or have to measure to be save for the tires.

So for example , if advice pressure is 70 psi , and you measure a cold pressure of 76 psi at an ambiรซnt temp of 100 degr F , dont blead air from the tire to bring it to 70 psi, it needs that 76 to give it lesser deflection so lesser heatproduction , because temperature differences between rubber and surounding air is also smaller so lesser cooling down .

Old-Biscuit
Explorer II
Explorer II
time2roll wrote:
"Cold" is relative. Set the pressure in the morning before you roll and before the sun hits the tires. Adjust up or down as needed. If you have moved to a different climate then repeat the procedure the next morning.


There you go....nice clear concise simple answer.

:B
Is it time for your medication or mine?


2007 DODGE 3500 QC SRW 5.9L CTD In-Bed 'quiet gen'
2007 HitchHiker II 32.5 UKTG 2000W Xantex Inverter
US NAVY------USS Decatur DDG31

time2roll
Explorer II
Explorer II
"Cold" is relative. Set the pressure in the morning before you roll and before the sun hits the tires. Adjust up or down as needed. If you have moved to a different climate then repeat the procedure the next morning.

Sam_Spade
Explorer
Explorer
Only if you will be in the "extreme heat" for more than a couple of days.
Starting out at 5 over is fine for a day or two.

After all, some folks insist on using the max. pressure on the sidewall and in some cases that is 15-20 PSI over what would be optimal.
'07 Damon Outlaw 3611
CanAm Spyder in the "trunk"

2oldman
Explorer
Explorer
Cold pressure
"If I'm wearing long pants, I'm too far north" - 2oldman