Tag axle air pressure setting

[Mike Shumack]

Hi BAC forum members,
This is my first post. I'm a new Beaver owner, and have a bunch of questions.

First question, what is the proper way to set the air pressure for the Tag axle "down force"?

The manual indicates the air pressure is set at or around 30 psi.
EDIT - I can't locate the section in the manual now where the "30 psi" statement came from - so I may be wrong about this initial setting.

Since the Tag axle is single tire and rated for 10,000 lbs, where the rear axle is dual tire and rated for 21,000 lbs, it would seem that having the Tag axle carry 1/2 of the total rear end weight would be best.

I'm thinking the only way to know what air pressure setting is correct is to have the (rear of) MH weighed.

Do you adjust this depending on changing loads - or is it set it once and don't worry about it again?

Also, when the Tag axle is lifted will it automatically drop when the transmission shifts to second gear - or do I need to press the Tag button to lower it?

[Jerry Emert]

I set mine about 3 years ago to take excess weight off the front axle.  The pressure that worked for me was 28psi.  Thats about what you mention so I would start there.  I haven't reset it since then.  I've weighed the coach a couple times and the front weight is within specs.  So I guess it's set once, eyeball it every now and again and have fun.  Mine is also automatic so I don't mess with it.  I'm told it goes down at 5mph.

[David T. Richelderfer]

Our coach's tag down-pressure setting was just over 30 psi (33?) when we purchased the coach.  When we axle-weighed the coach, we found the steering axle to be very near to slightly higher than the steering tires' maximum weight carrying specification - about 8,250 lbs for each tire at 120 psi for 295/80R22.5s.  So we reduced the tag down-pressure to reduce the weight on the steering axle.  But by this time the steering tires had already been damaged by too many years without covers and too much load.  When we replaced the steering tires, we purchased 315/80R22.5s after trying them on for a fit.

When we reduced the tag down pressure, if memory serves me, the reduction went from about 33 psi to maybe 27 psi.  We have not taken the time at this writing to reweigh the axles.  But having steering tires now that have a load rating of over 9,000 lbs at 130 psi is well over the steering axle's weight.

The tag axle raise and lower function is automatic as far as we were told.  My recollection is under 10 mph it will automatically raise.  Over 10 mph with the tag switch properly placed it will automatically lower.

[William Jordan]

Removing weight from the rear main axle  is only part of the picture. The more weight you take up with tha tag by increasing down pressure it adds to the front axle additional weight. Weight in the front axle on  most of these coaches are already maxed out by the couple I’ve looked at. I don’t want or need more !  My Marquis only has about 26 psi and around 6000 lbs on them when I’m not towing the car hauler. 28 when I do . I also keep 90 psi in tag tires , much more than required for the load , as my truck tire guy told be the scrub factor needs the type pressure to resist the cornering  side scrub
The tag provides stability , takes any overload off the duals but I certainly wouldn’t necessarily ever put 50 % of the rear weight on it unless something large was on the rear .. motorcycle carrier,  heavy trailer  tongue   weight etc.   
not sure how you lift is set up .. mine when “on” lowers in 2nd gear and raises in first. The switch is on or off .. I leave it off because in traffic i don’t want the wear of constantly lifting and lowering the axle .. when I don’t need or want it lifted like over bumps etc  . I only turn it on when tight corners such as for slow tight turns in a RV park. The auto lift in 2nd gear or higher is also helpful when I forget to turn it off so I’m not running at any speed and overloading the rear axle. I think of it as a safety feature not a way to use it in on all the time.

[Mike Shumack]

Thanks for the info.
I did find the section again on the air pressure - and it does start at 30 psi. There is a section in the manual (starting at page 87) on making these adjustments. I will need to wait until I can find a four-corner scale to do these calculations. I agree that it is best to leave the switch off so the Tag is not raising/dropping during normal traffic stops, then turn on the Tag switch when tight turns are made such at the RV park.

For now I'm just reading through the manual - getting ready for my "first" trip once my tag and registration are received.

[Steve Huber Co-Admin]

Mike,
This may provide some helpful info. It's also posted in Common Problems under the Technical Tab of the BAC website.
http://beaveramb.org/listings/location/tire-information/
Steve

[Keith Moffett]

Mike
Welcome to the club and family. 
We have all been beginers and I am with each new coach.  There is so much to learn each time.
28 pounds for us and the tag is off until needed.  I have the tire pressure at 110 on all tires.  I find it gives me breathing room on rough road impacts like transition strops and chuck holes.  This might vairy some as each tire manufacturer is different.
Enjoy your first trip!

[Bill Lampkin]

Mike, my suggestion is to not wait for a 4 corner weigh, just head to any truck scale and weigh all three axles. Adjusting the tag is easy, the manual says just lift and drop the axle  times. Adjusting the tag really changes the weight on the front axle. I have our 40' Lexington set so the front axle is about 14,000#. Check your axle weights, they are important.

[Mike Shumack]

There is a Smart Weigh place in Bushnell FL (not too far frmo me) - so I going to make an appointment and stay over at the park.
I'll load the coach with as much I as would normally take on a trip.

If I have a choice (and staying within the f**WR - which is 15,300 lbs) do I want more weight on the front end or less - for better ride and handling?
Or is more of a balance (like having the same "percent" of reserve capacity on each axle)?

[Steve Huber Co-Admin]

Mike,
My "knee jerk" thought is that you would want to try to maintain the same ratio of weight( frnt -back) as indicated on the mfgr's placard.
Steve

[Mike Shumack]

Thanks Steve.

I see the forum does not like the acronym for "Front Axle Gross Weight Rating".

Forums are so sensitive these days. 

[Bill Lampkin]

Mike, Whoever does your 4 corner weight should also have a recommendation on F/R weight  balance. They should be able to suggest a tag pressure that will give you the right F/R weight distribution. Glad to hear you are getting it weighed. Enjoy!