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Daniel3d · 05-07-2014, 02:36 PM

Just purchased a used Fleetwood Southwind. Price was right had a lot of things wrong. But there is not much I can not fix. So the hydralic levelers are now fixed, and the slide out. Rear AC repaired and the electric step. Had a few clearance lights out and the bulbs were good so that took awhile to trace circuits and repair broken wires.

The coach has 225/70-19.5 tires. They are Michelins. The tag on the door states tire pressure 65 psi. The previous owner had 115 psi in them. Road terrible with that pressure. The tire states 95 psi on them. The previous owner also had a Crossfire at 100 psi on one read dual. I replaced that with valve stem extensions with the rod in them so if something happens to the extension you do not loose air pressure. Have extensions on all tires now so they can be easily checked.

The real question is what air pressure should I be running? I know I can weigh the coach after loading it doing the front, total and rear to determine axle weight. But where to go to find the correct air pressure? Any recommendations.

Putting in the new front air bags was fun. But the old man trick of taking the AC vacum pump and getting all the air out, then putting the bags in boiling water for a few minutes to soften them up so they rolled easy made the job simple. Almost have the coach ready for the road after three weeks of work and she runs great now. To bad the previous owner did not take good care of it. But his loss was my gain. Should have a few good years in it still.

Mjay · 05-07-2014, 03:29 PM

Congratulations, and welcome to the forum. For the tire pressures, go to Michelin's website, they have a chart there for different size tires and axle loads. It will be a good starting point until you can get it weighed.

Mich F · 05-07-2014, 04:17 PM

As was previously mentioned.
Michelin Americas Truck Tire Load & Inflation Tables

jadatis · 05-08-2014, 02:13 AM

You can calculate it with use of my made calculator.
then you need to give maximum load and needed pressure for that of tires ( yours 95 psi already given).

From car ofcource the real weighed seperate wheel(pair) weights at best, second best axle-weighing, but as long as you did not do that, we will have to do with the GAWR's front and back ( gross axle weight ratings) .
Then also give the GVWR (V for vehicle) and the speedcode of tires ( probably N for up to 140km/87m/h) to make it complete.

GVWR and GAWR's can be found on american motorhomes at the same plate as the pressure advices. Tire data on the sidewall of them.

H. Miller · 05-08-2014, 05:00 AM

Not entirely to the subject but when were the tires manufactured (DOT date)?

Daniel3d · 05-08-2014, 09:12 AM

Down loaded the Michelin RV tire manuel. Will check the axle spec sheet in the coaches closet and start there. The tires had 110 psi in them when I got it. As I said the manufacture recommends 65 psi. I can start by adding to the manufacture axle load spec. Which is a dry weight and add for the 65 gallon water tank in the rear and an approximate load. That will be a good starting point. The reciept for new tires is 4 years old. The tires have over 80% tread on them. Some minor checking on the side walls from weather. Tire dealer said that was normal and not a large problem for now. Thanks for all the advise. Finally found the air cleaner buried up in front of the right front tire so need to change that out. Should be ready for the road in a few more days. Ordered the last part for the AC/Heater system and all systems will be back in top notch shape.

Thanks for all the advise.

Daniel3d · 05-08-2014, 10:01 AM

Checked the mfg data sheet and the GAWR front is 5500 and the GAWR rear is 11,000. So the tire data psi in the coach is 65 psi which goes along with the Michelin RV Tire manuel which states Single Axle at 65 psi is 2755 x 2 would be 5510 and the duel would be 5200 x 2 for 10400. So the rears should be 75 psi which would be 5720 x 2 would be 11440. So my original thoughts of 70 psi for the front would be OK but not on the rear. So I will try 75 psi and that should work and be good for a start. I guess I get to concerned, but its all about safety. Like when I fly in a private plane. Since I used to fly I do a walk around and check everything even if the pilot does. It's my safety. Over inflated tires are just as bad as underinflated ones. They put more stress on other components in the syspension system. As well as reducing the braking efficiency because there is less tire contact on the ground. The side walls also help act as shock absorbers and when the pressure is to high it adds stress to every component like walls, ceiling shaking things loose and increasing the wear on every thing.

Once loaded I will see if I need to adjust it again. If does not take much to go from the 16500 lbs dry weight to the 20000 lbs max weight. Especially when the water tank adds almost 700 lbs if you run with it full. Add people, food, etc and it adds quickly.

Pikehunter · 05-08-2014, 07:21 PM

Quote:

Originally Posted by Daniel3d

The coach has 225/70-19.5 tires. They are Michelins. The tag on the door states tire pressure 65 psi. The previous owner had 115 psi in them. Road terrible with that pressure. The tire states 95 psi on them.

Duh

Previous owner was an idiot. You never exceed the pressure as stated on tire's sidewall. Subtract 10lbs and see how it rides and keep subtracting until you get to 65lbs which is about the lowest the tire should have in it.

H. Miller · 05-09-2014, 04:48 AM

"The receipt for new tires" doesn't tell you much. Several of our group have been surprised that a tire dealer would put 2-4 year old tires on their vehicle "as new". Many members also declare that a tire needs changing at 7 years of age - no matter the tread remaining or mileage.
DOT date (actual mfg. date)???

Ed-Sommers · 05-12-2014, 11:23 AM

using your favorite search engine, look up "tire pressure chalk line method", and use that method, starting with the recommended tire pressure, and adjust using the chalk method.

Ed

jadatis · 05-12-2014, 12:08 PM

It was a bit of a puzzle to get the maximum load of your tires out of your information, but managed it to be 3640 single and 3415 lbs dual.
at pressure of 95 psi.
Then you did not give the tag axle wich probably have the same tires, because 5500front +11000rear makes 16500lbs and not the 20000 lbs GVWR.
But not inportant cant even fill more then front and behind in my calculator.

Here the picture I made of it. Check if all the data are right and also give the GAWR of tag axle, then I will calculate for that seperately, and if they have other tires give the maxload an AT pressure.

It gives for wich weight and reserve the advice is given, so weighing might prove it to be exagerated or not.
Especially when you lift the tag all the weight is on the rear axle, if I understand right what a tag axle is.

To my estimation this is the highest pressure at wich still acceptable comfort and gripp. Another way of looking at it then the list of the tire makers wich give a minimum pressure for the load.

The 65 psi adviced is probably the AT pressure of the original tires of D-load and afterward the tires have swiched to the now using AT pressure for F load with 95 psi.
Can be I mis-interpreted your given information, then sorry and give the right data.

jadatis · 05-13-2014, 01:16 AM

Reading back I saw you only mentioned the tag on the door, wich , together with the missing part of GVWR I misunderstood you had a motorhome with a tag axle.
But then still the difference between the 16500 total of axles and 20000 GVWR is not explained.

Mich F · 05-13-2014, 06:53 AM

Quote:

Originally Posted by jadatis

Reading back I saw you only mentioned the tag on the door, wich , together with the missing part of GVWR I misunderstood you had a motorhome with a tag axle.
But then still the difference between the 16500 total of axles and 20000 GVWR is not explained.

That 20,000# might be GCWR , not GVWR.

jadatis · 05-13-2014, 02:16 PM

Dont think so, 3500 lbs for a trailer would be light for a vehicle of 16500 lbs.
I think TS is seeing the 16500 lbs GAWR's together for empty weight of the vehicle. But its a bit more then the GVWR , so what the vehicle is maximum allowed to weigh. GAWR's together is mostly a bit higher the GVWR to allow some weight shifting . My camble is GVWR 15000 lbs.
so the pressure advices given are for maximum loaded vehicle, and if you are half loaded you even can do with a bit lower pressure.
Mostly the loads are more then you estimate, so weighing is the best thing to do.