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Old 08-11-2016, 02:40 PM   #21
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Originally Posted by abi2001 View Post
Greenimp: the placard on our rig reads maximum, not minimum. We do know the difference. Thanks.

Airdale: this is what I read and understand too. I even found some great comparative charts online. I expressed that info and concern to my hubby but he said (claims/thinks) the hitch weight makes up for the extra support and wasn't worried about it, choosing to keep it at 65 because the run between 70-75 when riding. I agree with you completely. Thank you so much!

The tires currently appear to have bulges in the sidewalls, so it looks like they have internal damage from ride underinflated. I'm currently trying to convince hubby to upgrade the wheels and tires to 16-inch.
Your 70-75 psi is a HOT pressure and is not part of the discussion. The ONLY inflation to consider is the "cold" inflation. i.e. when tires have not been driven on or exposed to direct sunlight for the past two hours.

Stop guessing on the tire loading. Get on a truck scale and learn the INDIVIDUAL actual load on each axle. You will find the total of the axles is not equally distributed between axles. Once you know the actual load on each axle you should assume a 53/47% side to side split as almost no RV has its axle load split 50/50 side to side on all axles. The problem is you don't know which end is the heavy end so using the heavier end load number consult the load tables. This will tell you the MINIMUM cold inflation you need not based on a guess but based on facts and actual measurement.
All tires on an axle should get the same cold inflation.
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Old 08-11-2016, 05:51 PM   #22
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Lets look at this from the manufacturers view-point. The specs for the 31SAX fiver says it has a GVWR of 12060#. So the published hitch (1660#) weight is subtracted from that leaving 11400# on the axles. Divided by 2 = 5200# GAWR axles. What does the certification label have for GAWR (S)?

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Old 08-11-2016, 06:17 PM   #23
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Quote:
Originally Posted by Airdale View Post
Lets look at this from the manufacturers view-point. The specs for the 31SAX fiver says it has a GVWR of 12060#. So the published hitch (1660#) weight is subtracted from that leaving 11400# on the axles. Divided by 2 = 5200# GAWR axles. What does the certification label have for GAWR (S)?

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11400# divided by 2 is 5700.

5700# divided by 2 is 2850. That is the reason for the 10 ply tires. Air tire to 80 psi. Get Forest River to issue you a new placards.

If you have been running tire to placard psi, you may have permeantly damaged your tires and will be needing replacement.

IMO
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Old 08-11-2016, 10:44 PM   #24
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Update from OP: my husband finally took my advice. We've since upgraded our tires to 16" 14-ply, with rims to match and support. They're getting installed Saturday. Can't tell how tickled pink I am about the upgrade!
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Old 08-12-2016, 08:05 AM   #25
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The 80psi is the maximum cold pressure for an E-rated tire. However, in your case FR has determined 65psi is adequate based on your trailer weight. You can run the tires anywhere between 65-80psi. At 80psi, the ride will be a bit harsher.
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Old 08-12-2016, 10:18 AM   #26
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Sorry to jump in towards the end of this thread. I can start a new post if the moderators think so.

My tire pressure question is a little different. I've always believed that side-wall stress and tire wear were the two things you should be concerned with. The former is the culprit for blowouts. I've taken my 2016 Rockwood 5th wheel to a CAT scale near my home and have numbers for all of the axle, total, hitch, etc weights necessary to understand my rig. I live in Idaho and we can get temperature swings of 40 - 50 degrees between early morning hours to highs in the afternoon. It wouldn't be unusual to have cold temperature pressures to change drastically throughout the day. Not to mention the pressure differences due to altitude changes. I can leave my house at 4740' MSL altitude and 45 degrees F) and end up at a campground later in the day at 7100' MSL altitude and 90 degrees F. If conditions like that make a 3 - 5 psi difference in your tires (cold temp measurements), do I need to be worried about blowouts or just tire wear changes. I'm not sure how much pressure change from the max or recommended will adversely affect your tires?

Am I on ok here or do I need to watch the tire pressure more carefully?
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Old 08-12-2016, 10:21 AM   #27
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Which tire and load rating?

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Old 08-12-2016, 10:41 AM   #28
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Which tire and load rating?

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My rig is in storage at the moment so I can't remember what tires I have but the max tire pressure is 65 psi cold and has a load D rating. Btw, after these tires (new with purchase of camper) wear out, I'm going with a load E tire.

I'm going to my camper later today and can get more detailed information if you need that.... Thanks!
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Old 08-12-2016, 10:51 AM   #29
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I couldn't agree with Tireman9 more! I have a toy hauler and before I head out I weigh all of the axles and then weigh one side of the axles to make sure I'm not overloaded side to side. I have even added a link to the preset on the equalizer hitch to see what it did to the overall balance of weight right at the scaled. Pulling the 8000# trailer was a dream with my Toyota Tundra because I had everything balanced. I recently upgraded the TV but am setting up the new rig the same way.


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Old 08-12-2016, 10:55 AM   #30
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My opinion is you should be fine.....I'M M in the middle of a tire tesr, testing both D and E rated tires at the same time, and different brands....have approx 4000 miles on this, running 65 lbs cold....

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