Axle weights?

[MHRookie]

I’ve seen questions about tag pressure setting and I think each coach varies so....

what is your optimum weight on steer axle for driving comfort?

2003 dynasty 42’ w/ tag.

steer - 12000

drive - 17000

tag - 7000

In this example, what if the drive was say 14000... do you all reduce tag pressure thus reducing steer & adding drive weight?  My unit is totally empty so not real sure what current weight balance is.

at 115# air in steer tires, it sure seems like they have more belly than rear axles.  Ride is ok though.

 

just curious...  thanks for any insight.

[Frank Bergamo]

Kurt,

 

I try to get as much weight on drive axle as possible with steer and tag within specs. When doing this coach should be fully loaded with fuel, water, and whatever else you may be hauling or towing. Hope this helps.

[Paul J A]

54 minutes ago, Frank Bergamo said:

Kurt,

 

I try to get as much weight on drive axle as possible with steer and tag within specs. When doing this coach should be fully loaded with fuel, water, and whatever else you may be hauling or towing. Hope this helps.

Black and Grey tanks should be empty when weighing. The drive axle is the fulcrum point when adjusting pressure on the tag axle, so the drive axle carrying weight is affected minimally. I always had close to the rated weight on the steer, because you as you burn fuel you reduce the weight on it.

[W7BE_Bob]

Steer 14150, drive 19150, tag 5,000. Since the steer and drive are within a few hundred pounds of maximum the tag can't be changed.

[Ivylog]

OP, had a 04 Dynasty for 14 years. I’d start with 110 psi  in the fronts if you are not going FTime...80 in the drive and 75 in the tag. If loading for FT add 5 psi to those #s and then go weigh again with the adjustable tag psi at 40.

 

if you are putting tires on it, you do not need 295s on the rear. A 11R22.5 is the same diameter and probably the most common truck tire...$400 +/-. You have to run +10 psi as they have a lower load rating.

Edited April 8, 2021 by Ivylog

[amphi_sc]

I don't mean to hi-jack a thread, however I was just (re)contemplating what my drive tires inflation should be and if I stick with the original stickered tire size behind the driver's seat, or drop down a size.

Actual weighed Passenger side drive wheel position: 11,300

Actual weighted Driver side drive wheel position: 9,150

so Axle carrying 20,450 total, but a ton+ difference side to side

Tire Manufacturer's Inflation chart shows for the selected 295/80/R22.5 (load range H) dual position:

70 psi: 9,060

75 psi: 9.540

80 psi: 9,880

85 psi: 10,440

90 psi: 11,020

95 psi: 11,460

100 psi: 11,900

105 psi: 12,350

etc... 120 max psi: 13,890

What's the consensus for proper tire inflation?  Is there a consideration for when the tag is temporarily lifted? Should I stay with the spec'd 295/80/R22.5? or....

if I dropped down to an 11R22.5, the appropriate chart is:

  70      75     80      85      90       95      100         105         110     115      120

8760 9160 9520 9900 10410 10830 11250 11680(G) 11790 11900 12010 (H)

Would you stay with an H (axle is rated at 23,000) as was original equipment spec, or get by with a G pretty much maxed out at 105 psi and 11,680? But then if I lift the tag I'd overload a (G) at any inflation.

For my steers, I'd need to stay with the 295's as the actual weight exceeds the 6610 (H) lbs single rating of the 11R22.5's.  As the tag is rated at 12,000 (and actually a ton under as actually weighed and as down pressure set), the 11R22.5's should be enough there too.

I was going to put on new 295's tomorrow, but the date codes that came in from the warehouse were 0220 so I rejected them.  Didn't think to ask about date codes for 11R22.5.  At one point years ago, my thoughts had been if I had all 295's and I had to move a tire to the steers for some reason, I could.  If I mix in the 11R22.5's, that emergency option goes bye-bye.

Thoughts and opinions?

 

[W7BE_Bob]

Are those weights with full cargo, fluids and passengers and at ride height? Any way to shift cargo to better balance the drive axle? What about the side to side weight on the other 2 axles? Given your weights inflate all drive axle tires to the heavest side, ie 95psi 11,400lb. Ditto for the other axles. This is the tire manufactures recommendation. No consideration for lifting the tag as that is temporary and at low speeds only.

I would use the mfg spec'd tire. My tire guy said moving wheels on the same side would result in the maring of the current outside of the alloy rims by the drum. Only option is to unmount/remount the tires. No thanks.

[Ivylog]

2000 lbs difference on the drive concerns me... I would check your ride height on the drive axle. Pretty sure it’s 9” between the metal mounting plates. Hopefully the lite side is less than 9” or the heavy side is more than 9”. What are the measurements on the front? IF all 4 are 9” I would increase the 2 on the driver’s side to 9.5” and reweigh.

 

Overloading the drive axle (lifting the tag) concerns me more than overloading the tire since you can only do it at low speed. I haven’t raised my tag in a decade as the tire scrubbing is not an issue and turning radius is about the same. I have found 30 psi in the tag’s airbags gives a good balance.
Many new, overweight rigs have gone to a steering tag as many are carrying 12,000+ lbs...raising would overload the drive by 60+%. 

 

Once I put 315s on the front there was no need for 295s on the rear so 11Rs worked well for me.

[amphi_sc]

My actual weights were at about 80% fuel (mid coach position 150 gallon tank, not front centric), initial 100 gallons fresh water that had been partially used and thus shifted to gray/black tanks.  Propane about 65%.  All those tanks should balance side to side, however all my heavy tools and bay freezer are on drivers side but passenger side things I can't shift: big AquaHot outboard by drive axle, four 4D house Life Line batteries, 5 smaller 12V engine batteries, washer and dryer stack in passenger rear corner, entire bathroom on passenger side, headboard of bed and desk driver's side so heavier drawers/TV etc passenger side.... Hydraulic reservoir passenger side... Have had multiple weighings where we've adjusted the tag pressure and in every case (even when we shifted 2300 lbs total on the drive axle), passenger side drive 2000 lbs heavier.  However front axle balanced within 25 lbs side to side, and tag within 100 lbs. Air bags measure the same at ride height on level concrete.

Typically, in and out of my drive, I lift the tag as it is pretty much a full lock hard turn on concrete to not fall in the ditches, but at least it is smooth and slow...and staying off the brakes using neutral as needed.

I dislike the idea of Jan 2020 "new" tires so was considering asking the date codes on the 11Rs.  Maybe I'll see what the warehouse finds in a month but probably the same six tires from 2020.  My other two tires can age a while longer before replacing.

 

[thomasgibbens]

You need to refer to your manufacturer’s certification tag with recommendations for tire pressure and weight distribution first and if your weight distribution is very different, I would get with a chassis shop to check your ride height. You might need some adjustments to the air valves to get it within specs. Then adjust tire pressure based on their load. 

[96 EVO]

On 4/8/2021 at 4:12 AM, W7BE_Bob said:

Steer 14150, drive 19150, tag 5,000. Since the steer and drive are within a few hundred pounds of maximum the tag can't be changed.

You may actually be 150lbs over on your drive axle.

While researching wheel end seals for mine, I discovered even though Monaco lists my drive axle as 20,000lb capacity, the axle manufacturer rates it at 19,000lbs.

[Ivylog]

A 2007 Thunder has the same axle ratings as my 08 Navigator... 15,160- 23,000 & 12,000. My axle weights are 14,400, 22,900, & 10,500 which is a lot heavier than the Dynasty I put 11Rs on the rear.

Al H, it would help if you posted your axle weights.

[amphi_sc]

Hi Dick,

Currently my axle weights are 15000, 20450, 10000 (as occupied in the seats too...).  Yes, same axle ratings as your HR, but you appear to be about a ton heavier,  pretty much concentrated on the drives. My Coburg sticker specs all tires as 295's on 8.25 rims with inflation as 120, 100, 90 for the factory Goodyears it had 2 sets of tires ago.  (BTW, I thought Goodyear 670 295's wanted a 9 inch rim???  Anyway, ran Michelin since getting rid of the factory tires many many moons ago.  Properly inflated Michelin always looked squishier compared to the Goodyears but I guess that would be expected with the smaller tread width on the pavement.) Coach handles well ... in NM or AZ on a calm day seems like one could set the cruise, go back to make a cup of coffee ☕, then return to the driver's seat 😉🤭.

With passenger drive as heavy as it is, I was thinking the 11300 is about 1/2 the axle rating (for spindle, bearings, etc) so while I could unload the front a little by reducing the tag, it could put passenger drive up to 12800.  i.e. when tag pressure lowered to 48, tag unloads to 7300 and front down to 14400 but drive now over at 23600, so need at least 50's or more for down force.  So I was thinking where she sits right now is pretty decent.

Usually when up in the NW we'll sanity check the current situation for significant changes by driving over one of the unoccupied roadside scales the state seems to conveniently leave enabled for loggers.

Appears to me 11Rs (H) could handle duals of 11900 to 12010 at 115 to 120 psi, so heavy side at 11,300 still leaves a margin.  And easily handle the tag weight. I haven't yet asked the warehouse about date codes on those 11Rs.  I've put up with the Michelin early cracking on the 295's.  Sure hate to start off again with "new" tires already over a year+ old before they even hit the pavement.

Does this help getting inside my current thoughts?  And I think I hijacked the OP's original question.  Sorry.

 

[Ivylog]

I look for the scales left on too so I can weigh, especially those with room to weigh one side at a time. Part of the reason I’m heavy on the rear is I’m picking up 1800 lbs 3’ off the back adding 2500 lbs to the rear and 700 off the front.

Hi jacking even more... at 15000, I would go go 315s on the front. Yes, I know they are now not recommended on a 8.25” rim...were in the past when I starting using. I’ve reduced the front psi -12 for over 60,000 miles without any problems. The issue is a 8.25” rim is only rated for 7600 lbs which can be exceeded if you use 115+ psi. I put 40K on Firestone FS400 on my Dynasty. Took off 5 year old cracking Michelin’s and replaced with 315 HSR2sa Continental which run quieter at 40 mph and the Firestone’s were out of stock.

Not that it makes any difference to me, the Continental is still approved on a 8.25” rim with the following footnote: 315/80R22.5 tires used on 8.25” rims are restricted to a maximum of 7610 lbs at. 120 psi.

 

Edited April 10, 2021 by Ivylog

[amphi_sc]

That is indeed an interesting towing arrangement!  What's your tag down force set to?  I'd guess in the 70's.

I was thinking the 295's on the front keep the sidewall flex point where it was designed (for cord fatigue) and rated for 7830 @ 120 & 7600 @ 115gives more of a margin than derated 315's, even with the low rim rating.

[Paul J A]

4 hours ago, Ivylog said:

I look for the scales left on too so I can weigh, especially those with room to weigh one side at a time. Part of the reason I’m heavy on the rear is I’m picking up 1800 lbs 3’ off the back adding 2500 lbs to the rear and 700 off the front.

Hi jacking even more... at 15000, I would go go 315s on the front. Yes, I know they are now not recommended on a 8.25” rim...were in the past when I starting using. I’ve reduced the front psi -12 for over 60,000 miles without any problems. The issue is a 8.25” rim is only rated for 7600 lbs which can be exceeded if you use 115+ psi. I put 40K on Firestone FS400 on my Dynasty. Took off 5 year old cracking Michelin’s and replaced with 315 HSR2sa Continental which run quieter at 40 mph and the Firestone’s were out of stock.

Not that it makes any difference to me, the Continental is still approved on a 8.25” rim with the following footnote: 315/80R22.5 tires used on 8.25” rims are restricted to a maximum of 7610 lbs at. 120 psi.

 

You stated, "  a 8.25” rim is only rated for 7600 lbs" Who's rim? Alcoa. Accuride, steel, aluminum?

[Ivylog]

I doubt anyone on here has steel rims on the front so aluminum. I’ve seen as low as 7400 lbs up to our rims that are 7650. Looked up what a Alcoa 8.25” is rated... 2400 lbs but found it interesting that it’s rated for a 315 tire.

[Chuck B 2004 Windsor]

I have a problem with coach owners exceeding the weigh carrying capacity of their coach.  Exceeding the weight capacity causes more wear and tear on the chassis and tires causing premature wear.  Not to mention being a hazard to others on the road.  Chuck B 2004 Windsor

[Ivylog]

4 hours ago, Chuck B said:

I have a problem with coach owners exceeding the weigh carrying capacity of their coach.  Exceeding the weight capacity causes more wear and tear on the chassis and tires causing premature wear.  Not to mention being a hazard to others on the road.  Chuck B 2004 Windsor

Skimmed back through the posts and didn’t see anyone exceeding the CCC of their rigs or their axle ratings. The reason for using a 315 tire is to reduce the pressure by 12 which results in a less harsh ride up front. The lawyers are concerned that someone could put more than 115 pounds of pressure in a 315 which would exceed the rating of the rim not that it won’t work on an 8.25 inch rim. If you needed 115 psi not only would you exceed the rims rating, you would be above the axle rating also.

[Chuck B 2004 Windsor]

I have seen using oversize tires issue come up in years past.  The biggest problem that arises is the larger tire rubbing the inside of the wheel opening under certain conditions such turning into a driveway or a parking lot.  Damage can be done to the inside of the wheel well opening that can only be repaired by replacement.  In these days and times, it would be hard to find the part let alone getting it painted to match.  There has been reports that damage was also done to the forward and rear components such as air bags and the brush assembly..  Remember, not one size fits all.  Chuck B 2004 Windsor