About Tag Axles

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PeterH

PeterH

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Jan 17, 2016
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Sandpoint, Idaho
I was wondering if a tag axle on a 40' MH is usually standard on a specific model or if they were usually something you could order as an option when ordering something brand new from the factory?

I looked a 2003 MH with a tag axle and the owner was treating it as an special option on the rig and therefore bumping up his price by a couple thousand dollars.

Thanks,
Pete
 
  A tag is used to carry the additional weight of the heaver er motorhomes. Front and rear axles are weight rated (and restricted)
Over the rated rear Axle rating requires the tag to Carry the extra.>>>Dan
 
Adding to the prior comments, Federal rules placed a limit of 20,000 lbs per axle. A tag allows the weight to be shared, and it can also be used to move weight between front and rear axles. One downside of a tag is that tires on that axle can be "scrubbed" in turns. Meanwhile, the Feds increased the max weight per axle.
 
As Dan indicates, they're provided to carry the weight when needed, so I can't see them being an option. And you lose basement storage with that tag, not to mention the extra tire expense, so I can't see them as desirable if two axles will handle the max allowed weight handily for your rig.
 
Ok, thanks... as I shop around, I don't see many rigs with a tag axle. Obviously the heaver rigs will need a tag axle to comply with federal weight limits. That suggests that the entire coach must be heavier than other 40's rigs.

So does a tag axle imply a higher end coach?


Looking at some of the records from the factory for this coach, there is basically a $12,000 difference between two models of the same coach, with and without the tag axle.
 
It's not an option and few 40 footers are heavy enough to require help from a tag axle. There have been a few such, but not many because a tag axle adds substantially to cost (upfront and ongoing) and reduces cargo space (takes space that otherwise would be a storage bay). Tags are common on 42 footers and above, though.

Back in the day when gas chassis manufacturers were lagging behind the coach body builders, tags were sometimes added by the coach builder so they could build larger rigs.  I had a 96 Southwind 36 footer coach on a Ford F53 chassis with a tag and a friend had a National Dolphin 35 on a Chevy chassis with a tag. Without the tags, the coaches would have maxed out at 17,000 lbs but the tags got them up to 20k.  Nowadays gas chassis go to 26,000 lbs so tags on gas coaches are a thing of the past.
 
Motorhome can have up to 24,000 pounds per axle.  My motorhome has 24,000 pounds and a 12,400 pound with a GVWR of 36,400 and a GCWR of 46,400 pounds.  Here is the ruling and I quote:

In 2011, Congress passed the Moving Ahead towards Progress in the 21st Century Act (MAP-21; Public Law 112-141), which re-authorized U.S. transportation programs, including those for highway and bridge building, maintenance and improvement. As part of that bill, the Recreation Vehicle Industry Association (RVIA), with the help of the Indiana Congressional delegation, was successful in obtaining an exception to the federal law that limits vehicle weight on roads and bridges (the ?bridge formula.?) The amendment provides an exception, which is the same as the bus industry has had for several years, that permits motorhomes to carry up to 24,000 lbs. on a single axle (previously limited to 20,000 lbs.).


 
?So does a tag axle imply a higher end coach??
I would say yes, at least indirectly.  Higher end coaches have more amenities and higher end amenities themselves probably tend to be heavier.
Regarding tag tire scrubbing Tom mentions (and speaking of higher end coaches?) I assume a steering tag solves for that? And are any tags designed to retract for tight maneuvering?
 
Regarding tag tire scrubbing Tom mentions (and speaking of higher end coaches?) I assume a steering tag solves for that? And are any tags designed to retract for tight maneuvering?
Click to expand...
A steering tag would certainly solve the tire scrubbing issue, but is beyond my knowledge or experience. Friends with tags talk about retracting/raising the tag for some maneuvers. Again, I'll defer to the folks with knowledge/experience.
 
My 45' Beaver had a lifting tag (control was on the side panel), but its use was limited to under 5 mph. It didn't have any form of steering, though. That lifting takes weight off the tag and puts it on the drive axle, so it's not something you'd want to do very much. Note that the lifting mechanism also provided an adjustment (in the engine compartment) to change the amount of weight on the tag, thus a slight raising/lowering for normal operation. It's something that must be done with considerable care, and is best left to the factory or a very competent shop.

I might note that though the scrubbing is real, it didn't appreciably affect the tire life, since the tires age out long before the tread is badly worn and the worst of the scrubbing (sharpest turns) are at very slow speeds.

As to a "higher end" coach, the length and weight of a coach with a tag alone tend to imply that, since longer and heavier mean more expensive (as does tag), so manufacturers are most likely to reserve that for the "higher end" coaches.
 
Steerable tags have recently become more practical & affordable, so are found on several current high end models from American Coach, Newmar, Newell, Foretravel, etc.  Liftable tags have been provided on many motorhomes for the past 15 years and were used on very high end models (Prevost, Bluebird, etc) even before that.

Agree with Larry that tire scrubbing is an insignificant factor for a recreational motorhome. The tag tires are still going to age out before they wear out.  The '96 tag I had neither lifted nor steered and scrub wear was not even noticeable in the 3 years and 20k miles we owned it.  Could see the track of it, though, if I made a tight turn on dirt or gravel.
 
The inescapable part is the tag also adds a substantial weight to the rig with the extra wheels, tires and all the parts. These rigs usually go from 40000 into 50000 LBs.>>>Dan
 
The manufacturer determines whether a tag axle is needed and it's based on the weight each axle needs to carry.  As an example, consider the weight of a Formica countertop which probably weighs quite a bit less than one made of Corian.  A plastic toilet and sink will weigh much less than ones made of porcelain.

In other words, the more "goodies" the manufacturer provides, the more the weight increases with a corresponding need for adequate axle carrying capacity.  Years ago it wasn't unusual to find a motorhome with a Cargo Carrying Capacity of only 600 pounds.  By the time the owner added four people, a dog, some clothing and some food the motorhome was overweight.  Then there wasn't enough CCC for things like tools (they're heavy!), the kids' bicycles, a 50-lb. sack of dog food, and oh yes 40 gallons of fresh water.  Back then many motorhomes were grossly overloaded and they finally got some standards to make them more safe.  That's about the time the manufacturers started using tag axles, not to mention the tag axle manufacturers make their axles to handle heavier loads.

If you want a motorhome in the 40-foot range then you'll find more tag axles - and perhaps less underbay storage but the ability to carry more "stuff" whether it's canned foods, hobby items, or lots of tools.  It's one of the many tradeoffs we face when purchasing a motorhome.

ArdraF
 
Freightliner Custom Chassis claims their UltraSteer steerable tag ireduces the turning radius by 17% and has a 20% greater "turning angle".  I can't begin to explain how it could have that much effect, but I figure there must be at least some truth in their advertising claims, even if they've stretched the facts a bit.

https://www.fcccrv.com/chassis/xc/tag-suspension/#ultrasteer
 
I have the Freightliner XCL chassis with the non-steerable tag.  It does have a tag dump that automatically dumps in reverse, or I can manually dump it going forward under 5 mph.  It helps on gravel in turns for a campground that is tight and I notice the difference when I dump turning in the gravel to park in our garage.  Dump means it dumps the bags, it doesn't lift the axle on mine like other high end coaches.

I'm on year 7 and don't see any scrubbing issues with my tag tires. 

My drive axle is 20,000 lbs, tag is 10,000.  I've got a 44,320 lb GVWR and 59,320 GCVWR.  The design of my coach may have just tipped the scale on needing a tag, but as a result I have an OBSCENE payload (10,600 lbs).  From my last CAT scale weight, fully loaded with water I'm only weighing in at 36,300 so I have 8,000 lbs in reserve capacity.

My Meridian is a mid-line coach, so no... tags don't necessarily mean high end.  What they do mean is weight, and weight isn't necessarily concentrated weight per ft, it is also length.  Mine is the longest Winnebago made in 2013 at 43 ft 6", so the extra length adds the extra weight that pushed it into tag space. 
 
Our 43 foot coach has a non-steerable tag, and while I can't "lift" it, I can dump its air pressure independent of the drive axle, which helps (a little) when making tight turns at less than 10 MPH. The tag pressure automatically dumps when I shift into reverse. Our friends bought a new 45 foot Newmar with a steerable tag, and that coach can turn sharper than ours.

The only 40 foot tag-equipped coach I'm aware of that's still in production (at least I think it's still in production) is made by Newmar. Compared to other 40 foot non tag-eqipped coaches, the tag axle would take up a basement storage compartment, but that's not the case on 43 and 45 foot coaches. The storage is built in to the additional length of the coach.

I really like our tag. The RV feels very stable with none of the yawing, or porpoising I experienced with our previous two motorhomes. Weight capacities, both load and towing, is basically a non-issue. However, we just replaced all eight tires, and those two "extra" tires added about $900.00 to the cost, so there is a price to pay. It's worth it though (IMO.)

Kev
 
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