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03-21-2015, 10:52 PM
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#15
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Senior Member
Country Coach Owners Club Solo Rvers Club iRV2 No Limits Club
Join Date: May 2011
Location: Vancouver, WA
Posts: 37,725
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Quote:
Originally Posted by F4Gary
I think the factory placard applies to the factory sized tires, not manufacturer.
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Nope, it's for the standard size, manufacturer, model and weight range of the original tire ONLY.
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2009 45' Magna 630 w/Cummins ISX 650 HP/1950 Lbs Ft, HWH Active Air
Charter Good Sam Lifetime Member, FMCA,
RV'ing since 1957, NRA Benefactor Life, towing '21 Jeep JLU Rubicon Ecodiesel
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03-27-2015, 09:09 AM
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#16
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Senior Member
Join Date: Feb 2015
Location: Grapevine, Tx
Posts: 5,632
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OK, went to the local CAT scales and had my Southwind weighed.
Front axle = 6600
Rear axle = 11850
The placard in the coach says:
Front GAWR 7500 lbs
245/70 R 19.5 XRV tires at 95 psi cold
Rear GAWR 13500 lbs
245/70 R 19.5 XRV tires at 85 psi cold
I have Dunlop SP348's in that size and the placard on the tire says:
Max load single 4540 at 110 psi cold
Max load dual 4510 at 110 psi cold
Load Range G
I found this Dunlop brochure pdf, and it you go to page 5 on it, it basically has the same info as the placard on the tire.
http://www.goodyeartrucktires.com/pd...20Brochure.pdf
So can anyone decipher how much air to put in my tires other than the coach placard of 95 front/85 rear?
__________________
2004 Fleetwood Southwind 32VS W20 - SOLD!
ReadyBrute Elite towing a 2017 Ford Edge Sport
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03-28-2015, 09:30 AM
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#17
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Senior Member
Join Date: May 2013
Posts: 745
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I would give Fleetwood a call I'm sure they can give you some advice.
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2019 Tiffin Allegro RED 37 PA
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03-28-2015, 10:12 AM
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#18
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Senior Member
Join Date: Feb 2015
Location: Grapevine, Tx
Posts: 5,632
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Quote:
Originally Posted by rjsupersonic
I would give Fleetwood a call I'm sure they can give you some advice.
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I called them yesterday to make sure I had the right placard in the coach as there was a recall back then ('04). He wouldn't recommend tire pressures.
__________________
2004 Fleetwood Southwind 32VS W20 - SOLD!
ReadyBrute Elite towing a 2017 Ford Edge Sport
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03-28-2015, 05:41 PM
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#19
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Member
Fleetwood Owners Club
Join Date: Oct 2012
Location: Ask us tomorrow
Posts: 49
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Quote:
Originally Posted by Phil14
I had a tire dealer install valve extensions on the rear tires because there was no way I could fit the inflator on the valve stems . Took him an hour and he had to bend the extensions to fit but it was money well spent. Make sure you go to a truck tire dealer to get this done as a regular tire store might not do it. I also bought an air compressor to fill the tires because gas station compressor cap out at 80 lbs.
We have a 32 ft Storm and inflate to 85 lbs on all tires. Handles well and rides well too.
Hope this helps.
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What make of compressor did you buy and how long to inflate from around 80 to 90 psi?
Connie, Tony and Rusty - on the road in 'Arvey
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Connie, Tony and Rusty on the road in 'Arvey
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03-31-2015, 09:37 PM
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#20
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Senior Member
Join Date: Feb 2015
Location: Grapevine, Tx
Posts: 5,632
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bttt
__________________
2004 Fleetwood Southwind 32VS W20 - SOLD!
ReadyBrute Elite towing a 2017 Ford Edge Sport
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04-01-2015, 10:16 AM
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#21
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Senior Member
Join Date: Nov 2008
Location: Kennewick, Washington
Posts: 413
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Mr D has the correct answer. Try to find a Dunlap tire dealer and give them your weights, and ask for their recommendations for tire pressures. Your original tires were more than likely Goodyear 670s load range F.
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04-02-2015, 04:13 PM
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#22
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Senior Member
Join Date: Feb 2015
Location: Grapevine, Tx
Posts: 5,632
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I didn't realize tire pressures were going to be such a pain in the a...
__________________
2004 Fleetwood Southwind 32VS W20 - SOLD!
ReadyBrute Elite towing a 2017 Ford Edge Sport
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04-02-2015, 07:15 PM
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#23
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Senior Member
Commercial Member
Join Date: Mar 2010
Location: Akron, Ohio
Posts: 2,783
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Quote:
Originally Posted by F4Gary
I called them yesterday to make sure I had the right placard in the coach as there was a recall back then ('04). He wouldn't recommend tire pressures.
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Shame on Fleetwood. They are the ones responsible, by law, for providing correct information on the placard.
Now to your basic question.
Your axle scale weight can only be used if we assume an unrealistic 50/50 side to side split on the weight. According to some figures I have seen fewer than 2% of RVs made have that level of balance with many being off by 5% to 10% (up to 45/55 side to side.)
There are numerous posts on this forum on "tire load" and I have a number of posts on my blog on why this is important and hwo to learn the facts.
Your avatar shows an airplane so I will assume you understand the importance of knowing proper weight balance and distribution.
If you can't get actual side to side weight then be conservative and assume one side has 55% of the total axle loading.
Use a Goodyear Load/Inflation table to learn the minimum cold pressure based on that load number.
Finally learn the complete story by reading posts and information on web sites written by tire companies like Goodyear, Michelin and Bridgestone who have identical work instructions on how to weigh an RV.
__________________
Retired Design & Quality Tire Eng. 40+ years experience. Recognized in the industry and in court as an expert in failed tire inspection as I have performed thousands of failed tire "autopsies".
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04-05-2015, 12:15 PM
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#24
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Senior Member
Join Date: Feb 2015
Location: Grapevine, Tx
Posts: 5,632
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OK, so I went to the Goodyear inflation tables I found here:
http://www.goodyearrvtires.com/pdfs/rv_inflation.pdf
note, there are 2 245/70R19.5 lines, I used the second one for tires produced
after 02/2006
I went with 55% side to side.
Front axle is 6600, so 55% on one tire would be 3630.
On the chart is says for 3640 the pressure is 80!
Rear axle is 13,500 so 55% on one tire would be 7425/2 = 3713.
On the chart is says for 3655 it's 90psi and for 3970 it's 95psi. So interpolating is should be about 91 or 92 psi.
Now what? Put 95 is all the tires since Fleetwood says 95 in the front and Goodyear says 91-95 in the back tires?
This is harder than rocket science...
__________________
2004 Fleetwood Southwind 32VS W20 - SOLD!
ReadyBrute Elite towing a 2017 Ford Edge Sport
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04-05-2015, 03:32 PM
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#25
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Senior Member
Commercial Member
Join Date: Mar 2010
Location: Akron, Ohio
Posts: 2,783
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Quote:
Originally Posted by F4Gary
OK, so I went to the Goodyear inflation tables I found here:
http://www.goodyearrvtires.com/pdfs/rv_inflation.pdf
note, there are 2 245/70R19.5 lines, I used the second one for tires produced after 02/2006
I went with 55% side to side.
Front axle is 6600, so 55% on one tire would be 3630.
On the chart is says for 3640 the pressure is 80!
Rear axle is 13,500 so 55% on one tire would be 7425/2 = 3713.
On the chart is says for 3655 it's 90psi and for 3970 it's 95psi. So interpolating is should be about 91 or 92 psi.
Now what? Put 95 is all the tires since Fleetwood says 95 in the front and Goodyear says 91-95 in the back tires?
This is harder than rocket science...
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Ya it seems like Rocket Science but you only need to launch the rocket (do the math) once
You did the math correctly and now know the MINIMUM cold inflation to use.
Question do you have a TPMS?
If so I would set the warning to go off at 80/92. With this warning level you can monitor your pressure as you look for a safe place to stop. You might even find you have a slow leak and can make it safely to the next exit where you would hopefully have more options. The BIG bonus is that as long as you haven't dropped below 80% of 80/92 or 64 / 74 you probably have not done hidden tire damage so you might just need a tire repaie.
So you aren't chasing your tail every time the temperature drops and find yourself a couple psi low I suggest you bump your CSP Cold Set Pressure to 10% above your min infl
so CSP would be 88 / 101 If you want you could round that to 90 / 100 F / R
With your CSP at 90 / 100 you know you can lose 5 psi and still be OK for your load but once you are 5 psi low on any one tire you also know you need to add air at the next fuel stop.
After adding fuel simply measure the warm tire pressure and add 5 psi to the warm number for your new warm number. I bet you will find the next morning when the tires are again cold you will be within 1 or 2 psi of your target CSP.
Bottom line for you that you can put on an index card
CSP 90 / 100
TPM Warn 80 / 92
Damage 64 / 74
Time to blast off
__________________
Retired Design & Quality Tire Eng. 40+ years experience. Recognized in the industry and in court as an expert in failed tire inspection as I have performed thousands of failed tire "autopsies".
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04-05-2015, 06:03 PM
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#26
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Senior Member
Join Date: Feb 2015
Location: Grapevine, Tx
Posts: 5,632
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No TPMS and I need to get better valve stem extentions or extended valve stems. Hard to get any reading at all out of one of them.
__________________
2004 Fleetwood Southwind 32VS W20 - SOLD!
ReadyBrute Elite towing a 2017 Ford Edge Sport
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04-08-2015, 04:32 PM
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#27
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Member
Winnebago Owners Club
Join Date: Jan 2014
Posts: 54
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Air compressor is porter cable available at home depot and lowes. Fills the tires very quickly.
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04-09-2015, 08:57 AM
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#28
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Member
Fleetwood Owners Club
Join Date: Oct 2012
Location: Ask us tomorrow
Posts: 49
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Quote:
Originally Posted by Phil14
Air compressor is porter cable available at home depot and lowes. Fills the tires very quickly.
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Thanks - we'll check them out
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Connie, Tony and Rusty on the road in 'Arvey
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