How much air pressure are you running in your Tag Axle air bags?

[Mike Shumack]

I was planning to have my coach weighed (Smart Weigh) before my August trip but the Smart Weigh facility in Bushnell FL is closed to Sept 20th.
So I will need to make the trip first then get weighed when I get back.

I know there is no "one correct setting" for the Tag air bags - as the weight/loading of each coach is different - but I would like to have a starting point.

I'm also going to be carrying a 700lb motorcycle so I will need to bump up the air pressure a little for that.

Perhaps there is a general range (like 40 - 45psi). The manual says the Tag air pressure is "preset" at the factory (and requires adjustment based on actual coach weights) - what was the preset/starting number?

If you have Tag Axle, please post the air pressure you have the Tag set to.

Thanks

[David T. Richelderfer]

I believe our coach's tag-bag pressure was just over 30 pounds (33?) when I checked it five or so years ago after axle-weighing.  At the time we had 295/80R22.5 wheels on the steering axle and that axle weighed about 16,300 pounds full of fuel and freshwater, and empty waste tanks.  That weight, 16,300 / 2 wheels = 8,150 pounds, is right at the maximum weight bearing capacity for that size tire at full pressure, 120 psi.

When I returned home from that trip, I released pressure from the tag-bags down to 27-28 pounds to take some weight off the steering axle.  I have not changed the pressure since then even though I changed the steering tires to 315/80R22.5s... which have a maximum weight bearing capacity of 9,200 pounds each at 130 psi.

[Jerry Emert]

I too weighed my coach when I first got it and found the steer axle over weight.  I adjusted the tag pressure from 35ish down to 28.  Weighed again and was well under.  That's where I left it.  Have to weigh again soon since I just got new tires.
Jerry

[Bill Lampkin]

I would not 'guess' in setting tag axle air pressure. Simply go to a scale and weigh the steer axle, then adj tag axle pressure while you are on the scale. While travelling thru Ore and Wash, I can pull into a truck scale (not in use) on the hiway and check front axle weight. Just a few psi can really change your axle weight. Just get the front axle on any scale and set it then and there, don't guess. We are on the road and the coach has been parked overnight so if I gave you a pressure on my tag as it sits, that pressure would not be the working or in use pressure. Mine is set so the front axle weight is 13,800 to 14,000#.

Don't guess, weigh it.

[Mike Shumack]

Are you saying the best adjustment is to have the front axle loaded (to just under GAWR)?

So I go to scale, with front axle only on scale, and turn up Tag Axle air pressure until I'm reading around 14,000 Lbs on the front axle (my front axle is rated at 15,300lbs).

I'm not sure how this is done at a commercial truck scale - at Smart Weigh they figure it out for you. Would be good know.
Thanks

[Jerry Emert]

I just drove through.  Paid for the way and adjusted the tag pressure.  Went through for a reweigh which I think was cheaper.  It was under so I let it stand.  I'm aware of no formula to get an acceptable percentage of the max weight.  If it's under I'm happy.  Mine was 12,400 and I believe I have a 15K front axle.  23K on the rear which included the tag.  Still need a 4 corner weigh.  Maybe ignorance is bliss.  If so I'm really happy!!
Jerry

[Mike Shumack]

Jerry, did you stop your coach with just the front axle on the scale?
Where is there a truck scale near central FL?

Do you try to stop the coach so the leading edge of the scale is positioned at the mid point of coach (does it matter)? Maybe the weight reading is the same no matter where you stop on the scale as long as the back wheels are off the scale. I may be overthinking this.

[Frank Bergamo]

Mike, I run 30 PSI on my tag regulator. I came to this pressure after weighing all 3 axles, one at a time. I then adjusted regulator so I have as close percentage wise of max axle capacity on each axle. The front and drive axles on my coach were about 84% of max capacity. I could not get tag axle to come close to this figure. If I put more pressure on tag, front axle would creep to max capacity while drive axle would be under loaded. If I put less on tag, drive axle would creep to max capacity, while front axle was under capacity. IMHO, I would prefer to have drive axle loaded just a bit more than front axle, in that drive axle has four wheels and tires to carry load, than front, with just two wheels and tires to carry load. Also, if weighing axle instead of each individual corner, I would inflate tires 10-20% on each axle, over weight PSI recommendations to compensate for one side of coach being heavier than the other. This is why it is best to weigh all six wheel positions separately, taking the heavier figure and inflating tires on that axle, to proper PSI for the heavier weight. Then you can inflate all tires on each axle to proper weight PSI without guessing. The 10-20% over is just insurance to make sure that one side is not under inflated if coach is heavier on that side. Hope this helps.

[Mike Shumack]

I definitely want to have all wheels weighed - but I'll have to wait for that since the Smart Weigh station near me is closed until late September.
If I can hit a weigh station near me on the start of my trip northward I'll have a better idea of how to set the tag pressure.

Until then it sounds like a setting around 35 psi should be a good starting point (just a little higher than you guys since I will be carrying a motorcycle on the back).

[Jerry Emert]

Mike, no I drove on completely and got all weights.  Went in the parking lot out of the way and made adjustments.  Only took one time because someone on here with a similar coach gave me the "28" figure to use.  It worked.  I honestly don't remember where the scale was.  It was a CAT scale at a truck stop somewhere in Florida!  As far as alignment goes I'm not smart enough to worry about it!  I just pulled up to the box and pushed the button with my night stick!  Then I walk in for the weight sheet. Those things aren't set up for an RV and I can never reach the big red button.  I am also heading North shortly and will be looking for a new weight check soon.
Jerry

[Frank Bergamo]

Mike, most Pilot/Flying J or Loves truck stops have a 3 platform scale that you can get each axle on all at the same time. Go in and tell the scale operator what you are doing. It may take a couple tries to get axle load adjusted. They charge an initial fee, and then after the first weigh they charge I think $2.00 per weigh after that. You will get 3 weigh tickets, one for each axle. This weighs each individual axle so you can adjust tag regulator to get desired axle load as described in above post. Once you know and adjust axle load with tag regulator, then you can check tire PSI for weight load on each axle. Once you know weight load for tires, add 10-20% more air pressure to tires to compensate for side to side weight difference. You can find tire load charts on the web sites of your brand of tire. If you can find a scale that will accommodate all 6 positions individually, then take higher weight on each axle and adjust tire pressure to accommodate tire load PSI. On my coach, my tire pressures for tag are 80PSI, drivers 90PSI, and steer 100PSI. Hope this helps.