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-   -   Adjust tire pressure for cold weather?? (https://www.irv2.com/forums/f258/adjust-tire-pressure-for-cold-weather-558461.html)

jadatis 11-03-2021 05:31 AM

Quote:

Originally Posted by MN_Traveler (Post 5972640)
Jadatis - one final, not quite so delicate, attempt to sway you from your theory. Here in Minnesota it is getting colder. Just today, the "Low Tire" pressure warning went off in my car. Not because the tire lost air, but because the pressure is getting lower because the temperature is getting colder (all of the tires are showing lower pressures). IF your theory is valid, then please explain to all of us here why, many, many VERY smart scientists and engineers have not designed the pressure sensors that are nowadays installed in almost every car manufactured to .... correct for temperature and NOT issue a "low tire" warning just because the temperature has gone down????? The reason is because your theories are not only just plain wrong, they are uninformed and DANGEROUSLY wrong.

To all others reading this thread - please think very carefully before you give credence to the theories and advice offered on this subject by Jadatis.

I have read from motorbikes that had tmps , wich gave pressure calculated back to 18degrC/65degrF, and they must be using temperature reading of internal sensor.
The calculation then happened in the recever-unit.
But even an internal sensor does not give exact the temperature of the inside tire gascompound, but better then external sensors.

Forgot the name , but the writer behind you describes that he monitored the pressure during trip and changing ambiŽnt temperature, but did not worry about it and did not change the cold pressure. And that is to opinion the right way, better then maniacaly adjusting it every time.
I wonder if the valves wont wear out faster, from all this.

Kid Gloves 11-03-2021 07:34 AM

Quote:

Originally Posted by 2cyber71 (Post 5972661)
My normal cold pressure by my weights is 105 all around my Horizon.
I left Pennsylvania last December 26th my pressure was 99
Kept my speed at about 55-60 on the interstate until I got to 103 and then picked up to 65. By the time I got to Virginia I was running 115 and tire temps were normal all the way. By the time I got to Florida I was running 120
Never put air in or took it out.
Drove back north and by the time I got home I was running 105.

Best practice would have been to inflate to 105 (your normal cold pressure) prior to leaving Pennsylvania in December. As far as determining correct pressures, what your pressure “gets to” while driving is irrelevant.

Was there a difference in ambient temperature between December and the time that you returned to Pennsylvania? A 30-40F difference would explain why the cold pressure increased from 99 to 105. That’s a perfect example of why pressure should be set when tires are cold.

Kid Gloves 11-03-2021 02:33 PM

Quote:

Originally Posted by jadatis (Post 5973037)
Forgot the name , but the writer behind you describes that he monitored the pressure during trip and changing ambiŽnt temperature, but did not worry about it and did not change the cold pressure. And that is to opinion the right way, better then maniacaly adjusting it every time.
I wonder if the valves wont wear out faster, from all this.

Someone inflating their tires incorrectly and then not worrying about it does not validate your theory.

It might support your opinion. If thatís what you are seeking, youíve come to the right place. The internet provides plenty of opportunities to find someone who will agree with you, even if youíre both wrong.

How can you be given so much information that dispels your theories, yet remain so unwilling to accept any of that information?

wolfe10 11-03-2021 02:43 PM

OK, ambient temperature went from 90 to 60 degrees F this week (yes, in Florida) Stopped and added air to the tires.


Yes, the tires DID read the IDEAL GAS LAW, and followed it. So, I followed it as well. Cold PSI (before driving was too low-- added air).


Have done that every fall/winter since I owned a vehicle (about the same time I had to learn the IDEAL GAS LAW). See, higher education (in the sciences) IS worth something.

RoadTrip2084 11-04-2021 07:59 AM

Quote:

Originally Posted by wolfe10 (Post 5973619)
OK, ambient temperature went from 90 to 60 degrees F this week (yes, in Florida) Stopped and added air to the tires.


Yes, the tires DID read the IDEAL GAS LAW, and followed it. So, I followed it as well. Cold PSI (before driving was too low-- added air).


Have done that every fall/winter since I owned a vehicle (about the same time I had to learn the IDEAL GAS LAW). See, higher education (in the sciences) IS worth something.

Yes, this is the way. :)

jadatis 11-04-2021 08:24 AM

1 Attachment(s)
MN-traveler wrote in reacton to my long explantion next
I think you are partially correct in that at low ambient temperatures the risk of thermal damage is reduced, but if the tire is underinflated, you still have increased flexure, and thus greatly increased risk of strictly mechanical damage.

Now for ST tires they calculate maxload in the bigger sises for 65mph wich gives to my calculation , if realy maxload on tire and reference-pressure in tire 1.38 x the deflection then a LT tire.
The 1.1 x in my example for 40 degrF against 70 degrF. Is then much less.

OK many ST gave tire-failure, but I still think that was because of overheating, and not the exessive flexing.


Also calculated it for european "for trailer use only" tyres, wich calc in maxl for 140kmph/87mph instead of C- tyre( LT- tire) 160kmph/99mph, and it gave 1.14 x deflection , and those are used often enaugh ( but by these eresponcible Europeans ;) ) for 10 years without failure.

On trucktires in Europe almost always additional service descriptions then fi 154L and 156K.
Calculated that back to 1.06x deflection at 110kmph/68mph against deflection for 120kmph/75mph.
And you cant argue that its a different material or construction, because they write it on same tire.

See picture I made about 2 years ago, above the yellow line.

I agree that there is a limit to the more deflection, but 10% more is not it ( to my conclusion for what it is
worth).

jadatis 11-11-2021 09:42 AM

I wonder what all the tire-specialists here, think of my idea to use the higher cold pressure at 100degrF. Example : you determined 80 psi to be right for the axle on a E-load tire.
Then you leave the campground for a long trip in the end of the morning with ambiŽnt temperature 100 degrF. You filled the 80 psi at 70 degrF ambiŽnt temperature.
But then you measure 85.4 psi ( as far as you can measure it that acurate, yust for the example).

What must be done.

1 . Leave it at 85.4 psi cold even if that is above " maximum cold pressure " of tire.?

2. Bring back the pressure to 80 psi, becausse 80 psi has to be filled at ambiŽnt temperature?

My answer you will know, but then again, I dont call myself tire-specialist, only " pigheaded Dutch selfdeclared tyrepressure-specialist "

Kid Gloves 11-11-2021 12:13 PM

Check it again the following morning.

There is no other correct answer.

There are, however, incorrect decisions.

jadatis 11-11-2021 12:36 PM

But the following morning the trip is already done, so possible damage if wrong decided is already done.

Kid Gloves 11-11-2021 03:08 PM

Set it in the morning, then stop thinking about it.

NXR 11-11-2021 11:20 PM

Quote:

Originally Posted by jadatis
But the following morning the trip is already done, so possible damage if wrong decided is already done.

Not even close to accurate. If you're supposed to be at 80 PSI as determined by the actual weighing of the RV and the tire manufacturer's charts (unless these are ST tires which should be inflated to the sidewall pressure when cold) then low pressure is your enemy. A tire that is 20% low is considered to be flat, or 64 PSI in your example.

You may be confused by the pressure molded into the sidewall. That is NOT the maximum pressure the tire can ever see. It is the MINIMUM pressure needed to support the design maximum load weight of the tire.

My motorhome tires do heat up when running and can and do exceed the pressure molded into the sidewall. It's normal and expected and accounted for in the tire design.

Oh, and NEVER let air it of a tire that is not "cold", meaning it has not had direct sun on it and it has not been driven on for hours.

And buy a TPMS.

Ray

Tireman9 11-12-2021 07:56 AM

Quote:

Originally Posted by jadatis (Post 5981902)
I wonder what all the tire-specialists here, think of my idea to use the higher cold pressure at 100degrF. Example : you determined 80 psi to be right for the axle on a E-load tire.
Then you leave the campground for a long trip in the end of the morning with ambiŽnt temperature 100 degrF. You filled the 80 psi at 70 degrF ambiŽnt temperature.
But then you measure 85.4 psi ( as far as you can measure it that acurate, yust for the example).

What must be done.

1 . Leave it at 85.4 psi cold even if that is above " maximum cold pressure " of tire.?

2. Bring back the pressure to 80 psi, becausse 80 psi has to be filled at ambiŽnt temperature?

My answer you will know, but then again, I dont call myself tire-specialist, only " pigheaded Dutch selfdeclared tyrepressure-specialist "




Again you seem to have missed the point.:facepalm: Tire pressure is to be set when tires are at the AMBIENT air temperature outside on the start of a trip.:banghead: No adjustment is needed.:dance:


The only exception would be if you are inflating tires in a heated garage and the temperature is much colder. Example it's -20įF (-29įC) outside and the tires on the vehicle are in a warm building at 65įF (18įC). That would be when you would use a "Cold Inflation adjustment" chart that I published on March 12 2021 in my RVTireSafety blog.

jadatis 11-12-2021 08:33 AM

You seem to miss my point, and yust keep repeating your argument.

Its not always possible to check the pressure in the morning , and even in europe, 1ce a month checking is adviced and before a long trip.

My example was that exeption, checking before a long trip , but then you measure that 85.4 psi.

Then you argue to bring it back to 80 psi, and I argue to keep it at 85.4 psi, even if that is above referencepressure.

My idea is easyer, you dont have to do anything, and to my conclusions the tires run cooler when driving.

Kid Gloves 11-12-2021 08:49 AM

This is hopeless. Iím out.


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