Tire Pressure

TBYRNE · 08-09-2002, 03:00 PM

I can't believe how much conflicting info is out there regarding tire pressure! I leaving on my first extended trip tomorrow in my 1983 310MH, and when I checked my pressures the dealer had set them all @ 92#. Is this correct?
Now some facts: frt tires goodyear G159 19.5R
rr tires Pathfinder HSR 19.5R
both are load range F max pressure 110psi cold

I just weighed the rig today 80% loaded: Frt axle 5240#
Rr axle 8180#
Total 13420#
Should I be running closer to 80 psi? BTW, gas mileage is not my primary concern, safety is.

thenewkid64 · 08-09-2002, 03:46 PM

If you are running the right size tires with the proper load rating (based on the info you gave I think you are) you should always use the vehicle builders tire inflation ratings. Sidewall markings are for max pressure. Most manufacturers calculate ride comfort and saftey in when they post inflation pressures (remember ford and firestone). As I rememember the fornt are in the 60 PSI range and the rears are in the 45 psi range, but I strongly suggest you check the owners manual, or have somone with the same rig check theirs.

1985air345 · 08-09-2002, 03:52 PM

My 1985 345 manual says 75 psi front and 60psi on the rear. I do have a tag axle so I don't know how that plays into it.

When you find out, let me know. I'll put it on my website on a specs page.

**jcanavera** · 08-09-2002, 03:54 PM

Unless you have a tire loading chart for that tire, and the weights carried by each tire, you are just guessing. Note that even axle weight is misleading since motorhomes are noted to vary from side to side. If I were in your shoes and if you had no other information, I would not consider bringing those pressures down from what the dealer set them for.

While people can tell you what Airstream recommends, remember that that recommendation was for the tire that came equipped with the motor home when it was built. Tires built by different manufactures do not use the same weight/inflation charts. Did you replace the tire with the same brand and make?

I would advise you to check out the site http://www.motleyrvrepair.com/TIRES.HTM

You will get a lot of good information regarding tire inflation, weight and tire aging.

Jack

TBYRNE · 08-09-2002, 03:57 PM

I don't have an owner's manual specific to my rig. I have a generic binder with pressure info for the 28 foot models, it recomends 60# frt/ 45# rr!?

1985air345 · 08-09-2002, 04:04 PM

Ken ('kzener40') has a 84 310. I sent him a PM for assistance.
'Bfrank' also has a 83 310.

PeterH-79MH · 08-09-2002, 05:45 PM

cold inflation of 90 psi puts you close to 100 when hot. That makes for a very hard ride.
For comparison only: I also have the G159's and run the fronts @80psi and the rears @70psi on a 28' with a 80 gal fuel tank.
I used to run the fronts @ 70psi, but went to 80 upon advice of my front end alignment mechanic.

PeterH-79MH · 08-09-2002, 06:20 PM

Here is the link to the Load/inflation table of Goodyear RV tires.
The listing for G159's doesn't even have an entry for anything below 65PSI.
Max speed 75mph, Fred!
65psi-2350#
70psi-2460
75psi-2570
80psi-2700
85psi-2780
90psi-2880
95psi-3000
http://www.goodyear.com/rv/general/RVTable3.pdf

thenewkid64 · 08-09-2002, 08:20 PM

Peter,

Did you notice any great difference in ride or steering when you upped the pressure?

1985air345 · 08-09-2002, 09:36 PM

Ken's 1984 310 manual states:

"Under normal load conditions Airstream recommends the cold inflation at 75 psi in the front tires and 60 psi in the rear duals."

Obviously there are lots of variables from the manual.

Peter - I guess I'll have to live with that 75 mph INITIAL trip in my MH forever. I'd rather be remembered for speeding than hitting a brightly colored barrel.

thenewkid64 · 08-09-2002, 09:59 PM

I did not hit a barrel. I hit TWO barrelles! Thump , Thump.

The first one just bent the awning arm, the second one ripped it off the coach never to be seen by me again.

Fred,
Your rep is far cheaper than mine, as now I am going to have to put a high dollar Zip dee on because I cannot use the old holes for a Carefree or A&E.

PeterH-79MH · 08-09-2002, 10:04 PM

Brett, I didn't real notice any difference.
Fred, my manual continues with:
For sustained high speed driving over 65 MPH cold inflation must be increased 10 PSI above psi specified.
So, maybe the 80/70 is not far off.