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05-22-2017, 04:10 AM
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#1
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Senior Member
Join Date: Jul 2015
Location: Preston, England
Posts: 184
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225/70r 19.5 rear tire pressures
Hi Folks,
Just wondering what pressures you guys run your dual rears at ?
I'm on a 30ft chassis and have the tyres at 80psi, I wondering if that's a little low as they look a bit flat....at the bottom lol.
Thanks in advance for any replies.
__________________
94 Fleetwood Southwind.
454 TBI.
J.F.D.I
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05-22-2017, 04:36 AM
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#2
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Senior Member
Thor Owners Club Ford Super Duty Owner
Join Date: Jul 2011
Posts: 3,788
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Pressures will vary by coach make, model, chassis, axles, owner loading, tire rating, owner risk tolerance,,,. With my coach and normal loading I'm usually under the axle weight limits so I'll air up to what the axle maximum which for the tires I have is 80 PSI cold. To add a bit of wiggle room if air temperatures drop or other changes during our travels I add an additional 5 PSI.
Concerning the extra pressure beyond recommended, while on vacation last summer had the weight checked and found I was about 300 pounds over weight on the rear. Moving stuff around in the below floor storage and the souvenir rocks from the coach to the toad corrected the oversight.
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05-22-2017, 10:40 AM
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#3
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Moderator Emeritus
Join Date: Jan 2000
Location: West Palm Beach, FL. USA
Posts: 27,519
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You cannot make any decision for your tires based on somebody else's coach. The proper inlfation for your rear tires depends on the weight on the axle. If you can't get a scaled weight, use the GAWR (max axle loaded weight) as the estimate and base the inflation on that. You also need the tire inflation table for that size and brand of tire, but most brands will be close if not identical.
The Michelin inflation table can be found at Michelin RV Tires | View Michelin RV Tires load and inflation tables for motorhomes and recreational vehicles. | Michelin RV Tires
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Gary Brinck
Former owner of 2004 American Tradition and several other RVs
Home is West Palm Beach, FL
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05-22-2017, 01:33 PM
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#4
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Senior Member
Join Date: Aug 2001
Location: North America somewhere
Posts: 30,593
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You can't go wrong running what is stated on the federal tire placard in the vehicle. You will not find any tire mfgr. that recommends running less pressure.
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2000 Winnebago Ultimate Freedom USQ40JD , ISC 8.3 Cummins 350, Spartan MM Chassis. USA IN 1SG 11B5MX,Infantry retired;Good Sam Life member,FMCA. " My fellow Americans, ask not what your country can do for you, ask what you can do for your country. John F. Kennedy
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05-22-2017, 02:09 PM
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#5
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Senior Member
Join Date: Jul 2015
Location: Preston, England
Posts: 184
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Cheers guys but the coach info is for the older style 8r 19.5s and I've changed over to 225/70's. The max on the side of the tire is 110psi cold. I know I don't want to be up there but I'll add another 5 psi and see how we go.
I've weighed the total vehicle and it came to 6250 kilos. I'll have to see about getting the axles weighed individually.
Many thanks.
__________________
94 Fleetwood Southwind.
454 TBI.
J.F.D.I
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05-22-2017, 03:26 PM
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#6
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Senior Member
Thor Owners Club Ford Super Duty Owner
Join Date: Jul 2011
Posts: 3,788
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Somewhere in the coach there might be both a chassis manufacture sticker and a coach builder's data sheet/label that will list both tire pressure (which isn't applicable anymore) but it also should list front and rear Gross Axle Weight Restriction (GAWR). For my Thor built coach on a Ford chassis there is a Thor stick on the wall under the driver's side window and a large Thor data sheet on the back wall of a clothes closet in the bedroom. There are two Ford stickers. One on the firewall and one on the frame in front of the front axle that lists the same.
Use the GAWR limits to cross reference the tire manufacture inflation tables. Of course you're going to need to convert the numbers to metric based so round up as necessary rather than down. Inflating to sidewall listed pressure may be excessive which will affect ride comfort and steering stability.
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05-22-2017, 04:31 PM
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#7
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Senior Member
Join Date: May 2006
Location: SoCal
Posts: 1,123
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I am on a 208 length wheelbase f53 chassis with a 23,000 pound gcwr. My placard shows an 85 psi, I usually run 95 psi cold. I should also mention I am running 245 70r 19.5 tires
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