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Old 03-10-2014, 11:36 AM   #15
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Since I have had two blowouts and the one in front did significant damage. So I have hence been cautious about my pressures.

What I don't understand completely is using cold pressures so I have changed my thinking a little.

During the winter in Florida Ambient temp are 55-70 or more. But occasionally it drops to freezing. Where do I set my pressures? Here is what I do.

I usually set my tires in the winter at about 60 degrees. I use actual wt against the tire and rim tables and add a little to compensate for driving in colder temps. For example, I left home for Mississippi with temps about 35 degrees. So in the morning I make sure the pressures will support the weight.

As soon as you get on the road my tire pressures increase 10-15 psi.

So what I am striving for is winter cold pressures and summer cold pressures. I don't want to change pressures every time I drive to place with different temps.

When I returned home and check tire pressures at the temp I set them at, the pressures are pretty much what I set them at.

What I would like to see are tables that show pressures and temps where the tire is likely to blow since the pressures vary quite a bit while driving.

I hear in forums and seminars that the max pressures are compensated for by the mfgr when you set the cold pressures. To fully believe this I would like to see the test data that proves that.

So I will remained confused on the issue. Someday maybe the data will be published.
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Old 03-11-2014, 03:02 AM   #16
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Quote:
Originally Posted by al2ride View Post
I know that the posted pressure on the actual tire is a maximum pressure, but not sure about the pressure posted on the decal inside the coach. I do know that I have always kept my vehicles tires at the pressure posted on the decal usually on the door jamb or glove box. What I don't know if it's the same thing for a MH because of how much the actual weight can vary.

There has to be somebody that can speak about this with authority. If I had to guess, the pressure posted inside the coach is in direct relationship to the posted weight. Is that the weight of the coach as it was sold without any gear, water, etc.
For American vehicles the advice pressure on the plate has always been calculated for GAWR's, but with a formula that is inadequate and gives in the lower load/maxload ratio to much deflection.

European vehicles before 2000 gave 2 or 3 advices, after 2000 the american way only and called that normal loading advice.

before 2000 1st advice for normal use was axle weights determined by the car-maker for 3 persons and a little load , and gave for motor in front cars,
front higher pressure then rear.

2nd advice was for fully loaded and GAWR's where filled in the calculation for that , asuming that you where not allowed to go over that.

In the 1990's rear was often put at maxloadpressure or even maximum pressure of tire to cover little overloading wich often happens for normal cars.
Sometimes this was the 3th advice, for when towing.

Al these advices where for maximum technical vehicle speed.
And already calculated with a formula that comes to more the same deflection in the lower load/maxload ratio's.

for motorhomes you can asume that the rear axle begins at GAWR and so overloading is more rule then exeption.
Front thoug mostly way under the GAWR so can do with lower pressure then the advice given on the plate. And because most passengers and sertainly driver is sitting closer to the front axle, to high pressure there gives discomfort by bouncing

But behind sometimes have to have higher pressure then maxloadpressure/reference-pressure, to cover this little overloading and unequall loading R/L, wich is allowed by TRA up to 10 psi for LT and ST tires and even 20 psi for truck tires.

For the little overloading and unequal loading R/L look at the picture I gave in my last post.
See the weightdifferences R/L and that they are even crossed between the axles. You see that 9 out of 10 times for motorhomes.

So to end this already to long story, recalculate and if possibel weigh in the condition you drive , so fully loaded , and even preferably per wheel(pair) and fill them in my calculator, and you will have an advice pressure wich makes your tires last long and almost zero chanche on blowing tires.
And no , I also am not an authority in the field, but gathered a lot of info in time.
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Old 03-11-2014, 06:56 AM   #17
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Quote:
Originally Posted by jadatis View Post
For American vehicles the advice pressure on the plate has always been calculated for GAWR's, but with a formula that is inadequate and gives in the lower load/maxload ratio to much deflection.

European vehicles before 2000 gave 2 or 3 advices, after 2000 the american way only and called that normal loading advice.

before 2000 1st advice for normal use was axle weights determined by the car-maker for 3 persons and a little load , and gave for motor in front cars,
front higher pressure then rear.

2nd advice was for fully loaded and GAWR's where filled in the calculation for that , asuming that you where not allowed to go over that.

In the 1990's rear was often put at maxloadpressure or even maximum pressure of tire to cover little overloading wich often happens for normal cars.
Sometimes this was the 3th advice, for when towing.

Al these advices where for maximum technical vehicle speed.
And already calculated with a formula that comes to more the same deflection in the lower load/maxload ratio's.

for motorhomes you can asume that the rear axle begins at GAWR and so overloading is more rule then exeption.
Front thoug mostly way under the GAWR so can do with lower pressure then the advice given on the plate. And because most passengers and sertainly driver is sitting closer to the front axle, to high pressure there gives discomfort by bouncing

But behind sometimes have to have higher pressure then maxloadpressure/reference-pressure, to cover this little overloading and unequall loading R/L, wich is allowed by TRA up to 10 psi for LT and ST tires and even 20 psi for truck tires.

For the little overloading and unequal loading R/L look at the picture I gave in my last post.
See the weightdifferences R/L and that they are even crossed between the axles. You see that 9 out of 10 times for motorhomes.

So to end this already to long story, recalculate and if possibel weigh in the condition you drive , so fully loaded , and even preferably per wheel(pair) and fill them in my calculator, and you will have an advice pressure wich makes your tires last long and almost zero chanche on blowing tires.
And no , I also am not an authority in the field, but gathered a lot of info in time.
Thanks, good reading.
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