tire pressure

[wb13798]

what is the tire pressure in your tires. my service manual says 70 lbs . looking at my tires and the wear patterns say pressure is too low. i now have 12 ply tires and not the 8 ply michelins that came on the coach. my tire man says i should have a minimum of 85 lbs in the 12 ply tires.. what tire are other mh using and what is the pressure you are running????


///// ya live and learn , gets expensive some time//////

[ALANSD]

On my 280 I run 60 lbs front and rear. I had 85- 90lbs in it when I first bought the coach, and it always rode way too hard. I checked my gm manual and the airstream one and both said 55- 65lbs.
Since running at 60 I have improved the ride, and seen no more wear than before. My tires are the standard radial goodyears.

Also- when I drove it home the first time after purchase, the tires were too highly inflated, the airbags were underinflated. Changing that and redoing the rear shocks made a terrific difference in the ride. I also refer you to this thread;


http://www.airforums.com/forum...=tire+pressure

[shelocta]

Since I also have a 310, I though I would chime in. The A/S manual says for the 31Ft. it's 75psi front and 60pb1 rear. They also give the same numbers for the 28 ft because they both have the same G.V.W.R. I my case I ran the HM across the scales and it's 5300 in front and 8440 in the rear. This was with 80 gallons water and near full gas. They are Bridgestone's 8R19.5 and if you go the inflation guide at Trucktires.com the numbers come out about the same.
The folks at a very reputable tire shop were I bought then said 100 psi all around, Go figure.
While I'm typing I have a question. Are the MH's placarded by A/S. The VIN says 82 for my chasse but the A/S doc's say '83 for the coach. Could they both be right?
Cheers.....Bill

[wb13798]

i also have come across the chassis year being one thing and the model year another. i have a 1984 310 but the chassis is a 1983 chevrolet p-32 chassis. i have had to provide the vin to get parts ocassionally.
just returned from the tire shop (good year) and they wanted to put 105 lbs of air in my front tires. IM A LITTLE CONFUSED AS TO WHAT SHOULD BE IN MY TIRES. in a earlier post i stated my service manual says 70 lbs . not so ... my cover for the fuse panel has the spec for the chassis and that is where i got the 70 lbs for the tires.. tires specified 8r19.5 doesnt give ply rating.
maybe andy can shed some light on this one..

[ALANSD]

The Airstream manual says one thing, the chassis gm manual says another, I would suspect the Airstream would be right as the chassis were used for so many applications. I had 90 plus in mine it rode like a rock. With 60-65 lbs in all around it ride and handles much better. The tire shops with the 105lbs spec are way off

[Nye Thatcher]

The only accurate way to get the correct P.S.I. is to find the weight on, front right, front left, right rear duals, left rear duals, call your tire company for the correct P.S.I. If you havent done this you might be in for a surprise. Dont gamble. Weigh your rig loaded and tanks full. Good luck.

[Robfike]

Another way to arrive at the optimum pressure is to go by tire temperature. You can get a small laser type unit at Harbor Freight or the like. This is what we do with our race tires.
Check each tire in three spots, inner tread, center tread, outer tread. The relationship of these three readings will show if the tire is overinflated, just right, or underinflated for the load on that tire.
Take your coach out on the highway for at least 10 minutes, then stop and quickly check/record the temps.
If the center reading is more than the inner and outer, the tire is overinflated for it's load. If the inner or outer is higher than the center, it is underinflated for the load.
Knowing this, you can experiment with pressures to get the temps as close as possible. There will normally be a small spread across the face of the tire ie. inner=145, center=142, outer=140. This is just an example, your numbers will be different.
By doing this you can arrive at an optimum pressure for the fronts, the dual rears, and the tags. You can also see where most of the load is carried.
Hope this helps, Rob

[GlenCoombe]

Ah...Gentlemen, perhaps it would be wise to refer to the DOT info on the tires themselves... Remember tire technology has changed quite a bit since our coaches have been built.
Reference to tire presure by AS was written back in the dark ages. New tires should be given the care that the maker suggests, including pressure.
My 19.5" radials run 75 psi front and 80 psi rear. Keep in mind that if you overdo the front pressure you'll notice the handling getting a little skittish...to little and the steering becomes heavier.
More attention should be paid to getting the front air bags at the right 55-60 psi for comfort IMHO.
Proper inflation is all about safety go with the makers numbers but not max. inflation numbers as you'll end up bouncing down the road...

[noiva]

Chiming in with Glen - if you have the standard 19.5 - 8 radials, the only way to know for sure is to weigh your vehicle on a good truck scale. There are tire charts that give the psi required for different weights. After weighing my 370, I had to put 80 psi front, but only 60 psi back. Of course the weight in the rear is being supported by 6 tires instead of 2 as in the front. The max. sidewall pressure on my tires is 105 psi, but that's not a recommendation of what to put in there. The owner's manual gives recommended psi for front and rear, but mine didn't match the weight charts for the front. With the air bags handling the suspension, I've found the ride is actually much better following the load ratings.

[JVW]

check your rims, if they are alcola you will print on the rims the max. pressure for the rims. i think they say 90 lbs max.

[noiva]

Originally Posted by JVW

check your rims, if they are alcola you will print on the rims the max. pressure for the rims. i think they say 90 lbs max.

JVW,

Since you have a 1989 with Alcoa wheels just like my late 370, I think the max pressure was 110 psi for the wheels, but I wouldn't put my reputation on that. I do remember the max pressure was imprinted in the wheel, but I'm almost certain it was higher than the max TIRE psi. If you get the chance, I'd be curious to know what your wheels have stamped on them.

Best,

[bobchevy89]

PUT the pressure that is on the side wall. the tire companies put that on the side wall for a reason. they have done tests to determaine what the safest pressure is. People that try to second guess the companies often get in trouble.

[noiva]

Originally Posted by bobchevy89

PUT the pressure that is on the side wall. the tire companies put that on the side wall for a reason. they have done tests to determaine what the safest pressure is. People that try to second guess the companies often get in trouble.

Bob,

I was definitely NOT trying to imply ANYONE should use the pressure rating of the WHEEL to determine how much air to put into the tires. I was only trying to see if my memory about the wheel load rating of my 370 was correct at being able to handle more than the 90 psi that JVW had mentioned. If you'll look back at my post of 10-15-06, you'll see that I was in agreement with Glen, and others, that the only way to get the proper pressure was to weigh the vehicle as loaded, and then use the TIRE weight charts to determine proper pressure. The maximum tire sidewall pressure is not necessarily what one needs to carry. In fact, that varies by manufacturers of even the same size tires. I had two different maximum psi ratings on my 370 tires, even though they were the same size, because they were from two different manufacturers.

I hope this clears things up.

Best,

[JVW]

Noiva, i checked with michelin , they said my tires have a rating of 110 max psi, the rims i am running have a max. of 90 psi . from there they said check the front and rear weight. if the front axle is more than 6150 lbs. or the rear is more than 11,560 to please contact michelin. that is all i can tell you. best regards, jvw

[noiva]

JVW,

Thanks for checking those numbers! Since I no longer have my 370, I couldn't go look at the numbers. Anyway, I took the 370 to a truck scale fully loaded, and found I needed 80 psi in the front, and 60 psi in the rear. I'm suspicious you will be very similar since the 345 is so close to the 370. I couldn't remember the max. psi for the wheels, as you know, so I really appreciate that information. That's why I posted the entry about NOT inflating tires to the max. listed on the sidewall. If one did that in your case, for example, they would have over-pressurized the WHEELS by 20 psi! I am a little surprised the wheels are rated for only 90 psi, but since that's what is says, it's all the more important to follow the load procedure to set tire psi correctly.

Thanks for the info.

Best,

[JVW]

novia, the original mechelin tires were not rated for 110 psi max. the newer mechelin tire are rated at 110 psi. airstream's 1989 manual recommended that 70psi for the front , 60 psi for rear and 60 psi for the tag. air bags at
55 psi (front). using these pressures you would be well in the limits of the
rims. for the record i use 90 psi all the way around.
have a good one! jvw

[noiva]

JVW,

One note - I had the same manual recommending 70 psi in the front. I went to 80 psi after going to the scales and realizing it wasn't enough for the weight up front. I'm sure you're safe with 90 psi, but you may experience a better ride if you do the scale thing.

Best,