H3 Weights

[rff105]

Here are the weights i got today in the H3 full of fuel and water empty sewage holding tanks. Looks like we don't have much room for people, Featherlite pushed this one to the max. What does not make sense to me is the right side weights being so much higher than the left. Our coach has one slide on the left and i would have thought the left side would be heavier. The scale I went to was fairly level but i did only weigh the left rears and right front. I did not weigh every combination. The only item i can think of that is on the right side is the generator and inverters. The interior looks balanced from a weight standpoint to me.

[dalej]

Richard, very good post! I hope that you stimulate more owers to do the same.

When you know where your at, it makes driving a lot more relaxing doesn't it.

[rff105]

What tire pressure would you run? 365s front and tag and 315 drive duals

Prevost plaque says:
Front 105 psi
Drive 90 psi
Tag 80 psi

Featherlite plaque says:
Front 105 psi
Drive 120 psi
Tag 95 psi

Minimum by Michelin Specs for weights above:
Front 110 psi
Drive 90 psi
Tag 80 psi

[Ray Davis]

Personally I would vote for the weights as specified by Michelin. Let's see what others suggest.

Ray

[Joe Cannarozzi]

105

Our bus is considerably lighter than yours 41750 full of fuel and water, loaded with gear.

As for the drives and tag we run 100lbs. I would not ever run less than 100 in these tires no matter how lite the load. We experience no adverse wear patterns.

As for your steer. IMO that is an extremely large load to carry up there and 110 seems dead on. 100 is definitely not enough and any more than 110 would create a pressure situation in extreme heat conditions that would put them way too overinflated and hard.

On a side note we have suspension pressure gauges on trucks, use them like on board scales. The heavier the load the greater the bag pressure. For instance, empty I have 15lbs of air in the trlr bags and loaded (16000 on the axle) there is 60 lbs in them.

Your R-R bags probably have approximately 5 more LBS than your L-R. I do not think that it is enough of a difference to be a noticeable difference in ride.

[Jon Wehrenberg]

Joe, I'm going to give you something to think about....

You say initial pressures in excess of 110 PSI will create excessive pressures in hot weather. I'll take the opposite position. You can create a blow out in an underinflated tire in freezing temperatures because of excessive flexing and the resultant heat from that flexing. Conversely, the higher tire pressures will result in less sidewall flex, and less heat generated by a tire.

When Michelin establishes tire pressures they are reflecting what they have determined is necessary due to the load being carried and they realize that there are going to be high pressures created by the heat of driving or even the heat created by high ambient temperatures or the tire exposed to the sun.

I would set the tire pressures based on the Michelin charts. FWIW, on our original coach I used 70 PSI for the tag and I got 134,000 on the last set of tires (12.00 tires) and had 3/16 of tread left when they were pulled. No uneven wear.

As to the air bag inflation pressures this is solely a case of the pressure being dictated solely by the position of the arm on the ride height control valves. The fact that you can read the trailer (and maybe the tractor) air bag pressures tells me a couple of things. With practice you can relate pressure to weight. You could also change the dial on the pressure gauge to pounds of load, and with practice be able to relate that to internal air bag pressure. But in reality it is the position of the control arm on the valves that let air in or out of the system to maintain the ride height. I assume you have left and right hand valves like the coach has. In reality the pressures on one side of the trailer in a steady state turn will increase on the outside of the turn, while the pressures on the inside of the turn will decrease because the valves are merely attempting to maintain a specific height and not pressure.

[Joe Cannarozzi]

Agreed but 105 said that Michelin suggested 110 too. I would have to think that any more would create a noticeable difference in ride quality.

Agreed too about the air bags. I was trying to relate what on the road knowledge I have on the subject. With greater than 20000 on the drives I would have to guess that pressures there would have to be somewhere north of 75lbs.

If it were up to me all air ride trlrs. would have a ride height valve for each side as the bus does because of what you describe is happening in a turn, and I can feel that happening behind the wheel. I like to refer to that as-The Bobandweave and when you first go to air-ride it takes a little getting used to.

I think Mr. K-W does duel ride hieght valves on their 8-bag set-up.

[Jon Wehrenberg]

I doubt if you could detect a difference in ride quality between 110 PSI and the maximum tire inflation pressure of 130 PSI. I do think you would see a change in wear on the tread, with the greater wear in the center, but only detectable through measurement, not visually.

[Joe Cannarozzi]

Lets go on to the tag tire pressure. If you look at Michelin recommended pressures for the tag and compare that to what is recommended for the drives at the weights 105 posted and then add the fact that the drive weight carried is divided by four tires and the tag only two you will conclude that the weight per tire is more at the tag.

Yet they tell you to run 10lbs less in the tag tires Also they have included the word MINIMUM there.

I carry 11000 on the steers on my truck and put 100lbs. I'm using this as an example in comparison of the tag for a couple of reasons. I have 25 years of accumulated info, that weight is very similar and it is a single tire configuration.

When normally at 100 and a leak begins it is at that very threshold, 70 or 80lbs, that I visually notice the problem with a bulge in the sidewall and the tire squatting.

Armed with that info I would never run that pressure in a tag tire on the bus that is carrying more.

I think you would have gotten even better results with that mileage with more air there.

[Jon Wehrenberg]

I can't remember my axle weights but for my drive on my old coach I had to use 85 pounds based on the Michelin chart for dual wheels 12.00 size and 70 pounds for my tag single wheel.

I was just using the pressures they called for. As soon as we deviate from the recommended pressures we become test pilots.

My steer tires called for 108 pounds and if I recall the axle was around 13000 pounds.