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Old 11-10-2017, 01:13 PM   #1
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Tire pressure - wrong

I weighed my coach and found it fully loaded with gas, water, people and stuff to weigh 11,250 lbs. I also got the weight of both axles. I also got hold of the tire pressure weight chart for my tires.
The bottom line is the door sticker covers the coach as max weight, 12,500 lbs and is not the correct amount for less.
There is also a 5 lb bump for operations at 70mph.
According to the chart I need about 52 lbs to carry the load, add some for safety and the the speed bump, 62 lbs is what is needed.

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Old 11-10-2017, 01:45 PM   #2
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Originally Posted by groundpounder View Post
I weighed my coach and found it fully loaded with gas, water, people and stuff to weigh 11,250 lbs. I also got the weight of both axles. I also got hold of the tire pressure weight chart for my tires.
The bottom line is the door sticker covers the coach as max weight, 12,500 lbs and is not the correct amount for less.
There is also a 5 lb bump for operations at 70mph.
According to the chart I need about 52 lbs to carry the load, add some for safety and the the speed bump, 62 lbs is what is needed.
I was running 75 all around on my coach. Finally "looked" at the chart on the door frame, lowered rear to the 65 rating and found yesterday on 70 mile run, handles much better than before. Chart said 75 front, 65 rear. I'm gonna try lowering front 10 lbs. based on your post, see what it does.
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Old 11-10-2017, 02:08 PM   #3
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Yep.. I need to get my coach re-weighed now that our travel pattern has changed from 3 month+ snowbird trip (carry lots of stuff) to shorter durations... I was close to max - so using the max pressures on the placard.

I certainly am running at a much lower weight now - and should be able to reduce tire pressure.
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Old 11-10-2017, 04:02 PM   #4
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Now if you want to get even more techy consider the so called "cold" tire pressure is at 68 degrees. Goes up about 2% for every 10 degrees F.
https://en.wikipedia.org/wiki/Cold_inflation_pressure
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Old 11-10-2017, 04:14 PM   #5
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Originally Posted by groundpounder View Post
Now if you want to get even more techy consider the so called "cold" tire pressure is at 68 degrees. Goes up about 2% for every 10 degrees F.
https://en.wikipedia.org/wiki/Cold_inflation_pressure
Then take into consideration elevation changes also. In my opinion find what you like, adjust it cold (means before being driven, 1st thing in the morning), inflate to that & enjoy your trip. You can go nuts jacking pressures up/down for this/that, the tires are designed to handle temperature, elevation changes.
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Old 11-10-2017, 07:11 PM   #6
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Tables for tire air pressure as a function of load are usually the minimum pressure required, but there are other reasons engineers may specify higher pressures.

In my case 37 PSI is enough for the Michelins to carry the maximum front axle load, but Ford specifies 55 PSI. I usually run them at 50 PSI but won't go lower because it introduces too much sidewall tire flex which adversely affects handling.

Just saying minimums are just that, a minimum requirement. Going higher isn't necessarily bad or wrong.
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Old 11-10-2017, 07:34 PM   #7
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