Tread life for tag axle tires

[H3Jim]

What kind of tread life is everyone experiencing for their tag axle tires?

Mine are now bald, and I only have about 25,000 miles on them.  It seems like I should have gotten more miles from them.   I don't always (only 25% of the time) remove the air pressure from the tag axle suspension bags for those tight turns.  It looks like the steers and drivers should go many times that.  I do make many tight turns, and I can sometimes see the rubber I left on the pavement. 

So is this unusually poor? or somewhat representative of what I should expect.  I weight about 39,000 lbs in current trim.  I could be more careful about always removing air from the tag suspension bags, or even spend the money to install the air lifts so the tags are completley clear of the pavement for those tight turns.  Not sure if its worth the money to up grade to the lifting tag or not.

[jackhartjr]

Hi Jim, it sounds like you answered your own question...that you need to take the air out more often.  How long does it take to drain that air?  (Just curious, I don't know.)  Bottom line is that by taking a lot of the weight off of that tag...it will help save the tires.
In trucking, the slower you make a U-turn, the less wear to the 'dragging' tires.  So I would guess that if you failed to take the air off...that by making a very ssllooww turn, you would not scrubb as much rubber off the tire(s.)
Jack

[H3Jim]

easy to do, just a lever by the driver and it takes about 2 seconds, maybe 5 to 10 to fill back up.  But it sets off a beeper, and for some corners, since it makes the rear drop as it does not allow any additionoal air to go to the driver bags, and it makes me bottom out.

Does that sound like way too few miles for the tag tires?  I know they are going to be less, but that does seem awfully short lived to me.

[luvrbus]

Jim, you getting no where close to the wear it should be on the tags most of the people I know that have a Prevost take the steers off and install them on the tags because they don't wear that much.Time to make a visit to Dick Kaiser in Eugene when you travel to Busn USA this year he can put it back on track with the 3 axle alignment   

[bobofthenorth]

Something isn't right if your tags are wearing that fast.  I moved mine back from the steers when I bought the bus, about 60,000 km ago now.  I put them back there because they were worn out, as far as I was concerned.  They really don't look significantly different now.  I'm going to change them this summer, more because they look bad than because I really think they need to be changed.  I put new shoes on the drivers last summer and that makes the tags look really bad but I don't think they have changed significantly in 60,000 km.  FWIW, I don't pay any particular attention to lifting them.  Occasionally I will lift them to back into a particularly tight spot but we're talking about maybe 2 or 3 times per year for a few minutes that the tags are lifted.  To be honest I can't say that lifting them appears to make much difference as far as I can see - they come clear off the ground & it impresses people who are watching me back up but I can't see a whole lot of difference in how the bus handles.

[Nick Badame Refrig/ACC]

Hi Jim,

Luke regrooved my tags last year. I have clocked 22,000 since then and I see almost no wear in them.

??
Good Luck
Nick-

[H3Jim]

When I bought the bus, I put all new tires and rims on it, and had a 3 axle alignment done at the same time.  The bus has always been twitchy, but much better since I have loaded it up with more weight.  In the beginning, I had to concentrate ALL the time to keep it in a lane.  But even now I can tell without looking if anything is starting to pass me, even a Honda.I can tell because I can feel the bus get "pushed" a bit from the air pressure coming off the passing vehicle.  And yes, for big trucks I have a reflex to compensate.

I've replaced all the shocks too.  After all that, I suspect there is nothing else but either an alignment, or the bushings in the radius rods.  430,000 miles, but spent the first 390,000 on New Jersey potholes.  The bushings I've had inspected, and they don't look too bad yet.

[Kristinsgrandpa]

Check the weight on the drive and the tag axles. It sounds like your tags are supporting more weight than they should. (or the drives aren't supporting enough)

Expecially since the drives bottom out when the tags are unloaded. (not enough air in the drives) That would explain the squirmy behavior on the road.

Ed

[Len Silva]

I don't know much about Prevost, GM guy here, but there is most definitely something bad wrong with your bus.  You shouldn't have to fight it that much, shouldn't even notice anything but the largest trucks and then only with a significant speed difference.

It looks like you have looked at all the common remedies but I don't know how you can tell the condition of the bushings by looking at them. Change them out.  In my very limited experience with an old 4104, the radius rod bushings made all the difference and the rears even more than the fronts.  It was one of the least expensive and most effective changes to handling that I ever did.

Len

[H3Jim]

When I had the bus weighed, the  duals were 17,460 lbs, and the tags were  10,520 lbs.

[niles500]

Jim - I don't have my book in front of me - but the ratio from drives to tags looks like its off by about 3k lbs if my memory serves me correct - also when I dump my tags they get an inch or two off the ground on level surface - I don't think that yours should be different from the VIP's - FWIW

[Kristinsgrandpa]

There was a post on the BNO about this a couple of years ago and IIRC the posters said about 6 K.

At the time I thought that probably wasn't much more than the tag assembly weighed.

You might check the archives. Also knowing what it use to be you can check it now, pretty cheap, and know if it's changed. That info and the recommended weights info would help to eliminate one possibility.

HTH, Ed

[makemineatwostroke]

 Jim  most tags and boogies carry 10% of the GVW per side 40,000#= 4000 each side or 8000# for both

[Hartley]

I had my MC9 start that squirming stuff once and it took me a couple of months
of searching to find the solution... As it happened I had to make a hard stop and I just
looked in the mirror and noticed that the tags were locking up and smoking.

I went back and rechecked and finally found that the air regulator for the tags was way under pressure and there wasn't enough downforce to keep the tags from locking the brakes up. I reset the pressure to the factory setting and the brake problem was solved. Then I played with the pressure until the handling smoothed out and the squirm disappeared.

The pressure finally came out to about 36 psi and approximately 6,200 lbs loading on the tags. No more drift or squirming and steering is rock steady even with trucks passing on 2 lane roads. ( drives with 2 fingers now. )

Dave...

[makemineatwostroke]

Jim,your problem is not enough air pressure on your drivers I had this with my BlueBird when you lifted the tags it would drag just another thought for you since you have so much weight on the tags and I think all air ride buses have about the same working principal