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Author Topic: Correct tire inflation  (Read 3891 times)

Tom

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Correct tire inflation
« on: October 17, 2005, 01:58:33 PM »
Click here for an example of Good Year's tire inflation charts. Note that the correct tire pressure is based on tire size, weight load and whether the tire is mounted as a single or one of a dually (two wheels/tires). Determining the correct number from the chart requires weighing the coach, front and back and side to side, preferably weighing each wheel.

Using the 275/70R22.5 Good Year tires on my coach as an example (Note that I allow a little for side-to-side and other load variations):

Front tire load (single): 5,230 lbs
Tire pressure:                  90 psi (I use 95 psi)

Rear tire load (dual):    5,000 lbs
Tire pressure:                  95 psi (I use 100 psi)
« Last Edit: October 17, 2005, 02:45:00 PM by Tom »
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caltex

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Re: Correct tire inflation
« Reply #1 on: October 17, 2005, 06:11:15 PM »
Tom

That is the same way I set my tire pressures, also running 5 pounds over the recommended pressure. If you weigh the coach at maximum expected load, then it should be good for all your trips.
Robert

Tom

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Re: Correct tire inflation
« Reply #2 on: October 17, 2005, 06:39:56 PM »
That is the same way I set my tire pressures

Weren't you the guy who taught me how to do it  ;D  You even weighed my coach for me at that landscape materials place.
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caltex

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Re: Correct tire inflation
« Reply #3 on: October 17, 2005, 10:29:48 PM »
Good thing we got there in time, they went out of business about six months later.
Robert

Howard R

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Re: Correct tire inflation
« Reply #4 on: October 18, 2005, 10:08:49 AM »
Also note that going much or a lot above the recommended pressure can have a big effect on not only the ride, but also the handling ... at least in my experience.

I do agree with the 5 psi over the chart recommended pressures by the way, it gives you a reasonable cushion.

When going through the process of getting new tires, coach weighed, then reloaded for better weight distribution, weighed again I went from max sidewall pressure (tire dealer CYA I think) to about 15 pounds over chart to final chart + 5 psi ... ride changed dramatically as would be expected, but there was also a large change in handling .... much better at the recommended pressure.  I often wonder reading bad handling reports how much is due to more tire pressure than recommended or needed.

In my opinion and experience + 5 is ok, + 10 ore more can affect handling as well as ride.

Howard
2001 Fleetwood Southwind 35R
V10   F53
2003 Jeep Liberty Toad
Minnesota

Tom

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Re: Correct tire inflation
« Reply #5 on: October 18, 2005, 10:18:40 AM »
You're right about both the ride and the handling Howard. I happened to mention them just yesterday in this message.
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Ned

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Re: Correct tire inflation
« Reply #6 on: October 18, 2005, 10:25:43 AM »
The actual tire pressure while moving will vary considerably, depending on temperature, speed, and sun.  Our tires run 10-20 psi over the cold pressure while under way.  The sunny side tires might be as much as 5 psi higher than the shaded side.  The Pressure Pro really gives a lot of insight into tire behaviour.
-- Ned -- Fulltimer 1997-2013
1997 Holiday Rambler Endeavor LE
2007 GMC Canyon

Jeff

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Re: Correct tire inflation
« Reply #7 on: October 18, 2005, 11:08:09 AM »
The actual tire pressure while moving will vary considerably, depending on temperature, speed, and sun.  Our tires run 10-20 psi over the cold pressure while under way.  The sunny side tires might be as much as 5 psi higher than the shaded side.  The Pressure Pro really gives a lot of insight into tire behavior.

Ned:

I put the Pressure Pro transducers in when I had the tire pressures within 1 pound or so on my tire gauge. After the first couple of days with pressures varying all over the map I spent another hour getting all transducers to read EXACTLY the same pressure cold.

An hour down the road and the numbers are all overthe map again! ??? ???

For those who haven't installed them yet don't waste the hour like I did. :P

Tom

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Re: Correct tire inflation
« Reply #8 on: October 18, 2005, 01:47:19 PM »
I think Howard and I were talking cold tire pressures  ;)
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BernieD

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Re: Correct tire inflation
« Reply #9 on: October 18, 2005, 01:53:42 PM »

I put the Pressure Pro transducers in when I had the tire pressures within 1 pound or so on my tire gauge. After the first couple of days with pressures varying all over the map I spent another hour getting all transducers to read EXACTLY the same pressure cold.


Jeff

As you said getting the sensors to read the same as your pressure gauge is an exercise in futility. The sensors have a +/- error factor of about 3% so 2 tires conceivably could be 6#s apart and both read 100#s with your pressure gauge. The system is designed to warn you of change and loss of pressure. After a couple of mornings of readings, I have a pretty good sense of what each tire is going to readout, and that is what I look for. As long as they don't change much day to day I leave them alone.
Bernie & Marlene Dobrin
Home is Goodyear, AZ
Missing our Travel Supreme

Howard R

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Re: Correct tire inflation
« Reply #10 on: October 18, 2005, 08:59:22 PM »
You're right about both the ride and the handling Howard. I happened to mention them just yesterday in this message.

Boy I'm having trouble keeping up!   ;D

And yes, like you I was talking cold tire pressure.

Howard

2001 Fleetwood Southwind 35R
V10   F53
2003 Jeep Liberty Toad
Minnesota