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Old 07-16-2015, 07:58 PM   #1
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tire pressure?

I have the FR3 30DS. When I picked up the RV, the tire pressure was set to ~82 psi.

Some time later when I was having heavy-duty anti-sway bars put in, the service technicians told me I should be running at 100 psi. So I did.

Some time after that, I took the RV in for some work (Lazy Days in Tucson) and they changed the pressure back to 82 psi, saying I should use the value on the sticker in the RV, not the max shown on the tires.

Today, I took 'er in for some more work (broken slide cable) to a certified FR3 dealer, and these people changed it back to 100 psi, saying the tires will heat up too much if I run them at 82 psi.

Help!! I'm thinking of splitting the difference and running them at 90 psi. For others with the FR3 what tire pressure do you run at?

Thanks.

Barbara
2014 FR3 30 DS
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Old 07-16-2015, 08:43 PM   #2
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Congrats on entering into the proper inflation spin cycle. The 82 psi comes from the coach builder (not ford). The 100 psi comes from goodyear and is the max cold inflation pressure for the tires based on their testing.
Neither one maybe correct for your specific application. Here is a link to Goodyear info on exactly how to find out what your correct cold inflation pressure should be:
http://www.goodyearrvtires.com/pdfs/tire-care-guide.pdf

So get out the abacus and head to the scales, or not.
BTW, I refer to those who tout max cold pressure under all conditions as "Blow Hards", Lovingly if course.

I hope this helps you to get to an informed decision.
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Old 07-16-2015, 08:47 PM   #3
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The best way to learn the correct inflation pressure for your MH is to learn the actual weight on the tires.

Tire "stickers" or placard is a reasonable estimate for the tire inflation but it is still an estimate as no one really knows how many bowling balls in your collection that you cart around with except you.

You need to do the following:
1. You need to know the actual load on each tire. This means you need to get the "corner weights" or loading on each of your MH 4 corners. This is not easy to do unless you attend a large RV event where the service is offered.
2. If you can't get the actual load on eaxh end of each axle then you can get a reasonable estimate by assuming you do not have a 50/50 side to side loading (only a very small % or RVs really have 50/50 side to side weight distribution) but you can use 47/53 for the estimate.
3. Load your RV with the water, propane cloths, bowling balls, food, fuel etc that you might carry and find a truck scale and get the weight of the front & rear axle. Apply the 53% factor and use that figure to estimate the load on the "heavy end" of each axle.
4. Look up the Load Inflation table for your size and brand tire and that will give you the MINIMUM cold inflation you should be running.
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Old 07-16-2015, 08:56 PM   #4
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i'll throw my 2 cents in as this frustrated me to no end. got completely different answers from the rv dealer, a goodyear service center, and the goodyear support staff. but the most insane issue I had was that the sticker on the rv that came from forest river was for a completely different tire than the tires they actually installed on the trailer. have you looked at the installed tires vs the tires mentioned on the coach sticker? how can the dealer say follow the sticker with out verifying that the installed tires are what is on the sticker?
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Old 07-16-2015, 09:02 PM   #5
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Step one, get it weighed, corner weights would be nice (weight on each tire(s)) but front and rear axles will be acceptable.

step 2, download the tire pressure table from your tire manufacture. Look up your tire weights in the table and it will tell you the minimum pressure to support that weight.

On mine, the coach placard says 100psi, but the table says 70 psi. I run 80 psi in all 6 of mine.
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Old 07-16-2015, 09:04 PM   #6
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If you bought the RV new it is the dealer's responsibility under Federal Regulation to have the Placard information match the tires & axles built in the RV.

If the sticker did not match the tire then you can file a complaint with NHTSA as this might constitute the need for a recall (replacement og the sticker or the tires) by ForestRiver.
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Old 07-16-2015, 09:10 PM   #7
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Thanks to all for some good information. I did get the RV weighed at an RV boot camp and will look up the recommended inflation for the tires. Will post the result once I've slogged through it.

Barbara
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Old 07-17-2015, 07:55 AM   #8
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Tireman -

My MH originally came with General tires (2001). The seller just installed 4 new SAILUN S637 225/70R19.5 just before I bough it last fall.

REMEMBER - You should also get the MH weighed when its fully loaded and ready to hit the road. Thats the weight you should use when determining the MINIMUM tire pressure from the table.

When I weighed my MH right after we bought it, my numbers came up very close (within 200 lbs) to the original 2001 numbers posted by Coachmen on the sticker.

I've ran across a lot of threads where people have indicated what their sticker says. From my observations, I'm willing to bet when the coach builder posted recommended tire pressure on their sticker, they simply went to the tire manufacture table and found the highest minimum pressure for that tire. i.e. on mine, its 100psi, and thats what they posted the tire pressure at.

That pressure (100psi) may not produce the best ride or handling, but according to the tire manufacture's table, that pressure is perfectly acceptable for the weight (Its well above the MINIMUM for the weight)

NOTE - The table lists MINIMUM pressure for a weigh. i.e. if your tire is supporting "X" weight, you must have at least "Y" amount of pressure in the tire (measured cold, i.e. you haven't been traveling on the tire over the past 8 - 10 hours.)

Caution when you use the table as there are usually two sets of pressures listed for the weight the tire is supporting.

One pressure listed is for tires that are used as "dullyies" configuration, and the other pressure is for tires that are used as "single" i.e. front or tag axle.
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Old 07-17-2015, 04:08 PM   #9
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So you know the weights on seperate wheels or axles , and most likely in the loading you drive around with .

Then if you give all the information of tires and those weighed loads of motorhome, I will calculate an advice for you and give picture of my filled in Motorhome-tirepressure-calculator.
In that I use a 10% reserve above the weighed loads and calculate with a saver formula then the ( american) tiremakers use to make their pressured/loadcapacity lists.

And lately I even include the maximum speed of tires and the maximum speed you use in my advice. Will in time include that in my calculator.

My prediction is that the advice will come close to the 100 psi and then still comfort and gripp acceptable, and reserve for things like , pressure loss in time, misreadings of weight and pressure scales, unequall loading R/L ( that 47/53% Tireman9 mentioned) etc etc.
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Old 07-19-2015, 08:29 AM   #10
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So, I found the measured weights (in lbs) for the four corners of my RV:

RF 2950 RR 5150
LF 3000 LR 5300

My tires are Goodyear 245/70R19.5

According to the table, in Single configuration they should be at 80 psi for 3640 lbs, and in Dual configuration they should be at 80 psi for 3415 (there are no values listed below these). I assume the Dual values are per tire, for which I'm at a max of 2650 lbs. Based on this, I think I should go back to the 82 psi they were originally set at.

Of course, these weights were a year ago, but at least they give me a ballpark idea. Looks like I need to find a place to get the weights done again.

Thanks again for the guidance.

Barbara
2014 FR3 30DS
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