Front Axle Weight and Tires

[Norm Green]

In preparation to obtaining new tires on our '06 Thunder, I drove the coach onto some truck scales.  The coach has the original Goodyear 295/80 x 22.5 tires on all but the front which has Michelin XZA2 Energy, (H rated) of the same size.  I obtained the weight of each axle individually.  The front axle was 15,760 lbs, the drive axle was 17,760 lbs and the tag was 9,960 lbs.  The coach was fully loaded, with full water, near empty gray and black tanks and all the items needed to live in the coach for a month.  The drive and tag axle were about what I expected, but the front axle was a lot higher than I thought it would be.  
My concern is trying to select a tire that will support the front axle weight.  The current Michelin’s load at 120psi is 7,830 or 15660 for the axle, just short of the actual weight.  I am in Bend at BCS now for some repair work and plan to go to Eugene to purchase the tires using the Monaco National Plan.  It has been suggested that I might be able to increase the size of the front tires which would give me more capacity for any given pressure (315/80 x 22.5 is an L rated tire and rated at 8,530 lbs at 120psi).  It has also been suggested to decrease the weight on the tag, moving it to the duel and that may decrease the weight on the front.  Not sure if this would work or not but I am not sure I want the tag much less than the current 9,960.
Has anyone increased the size of the front tires only on a similar rig or any suggestions regarding the load on the new tires?  As usual, comments and suggestions are appreciated.  

[Steve Huber]

Norm,
You probably don't want to hear this, but I'd suggest you get the coach re-weighed to obtain the weights on each end of each axle. The weight per axle is not distributed equally so 50% of the total weight is not an accurate figure.  For example, on my 01 Contessa (40' /no tag), fully loaded and fueled, the weights were as follows: Front axle: 10094, Right front; 4866, left front; 5228.   Rear axle; 18424,  Right rear; 8520,  left rear; 9904.
Steve

[MarcRodstein]

Steve is right. Often there are sizeable differences left to right, which can be somewhat dealt with by rearranging your loading. You want to stay under rated weight on each and every tire. If your drive axle has, as I think it does, a 20,000 lb rating, then I think it is totally reasonable to unload the tag a little, therefore also unloading the front axle, as long as you don't exceed the weight rating of the drive axle.

Putting larger tires on the front could bring problems, as there may not be sufficient clearance in the wheel wells.

[Jim Skatzka]

norm, i can tell you on our 06 patriot saratoga i switched to 315's without any clearance problems!  go for it, its just one more added measure of safety where you can use it most.    jim

[Norm Green]

I understand the ideal is to weigh each tire individually but I don't have the ability to do that right now.  My concern is that regardless of the individual wheel weight, the total weight approaches the load limit of the current tire size.  Jim, I appreciate your response that you have changed to the 315 size.  While here at BCS, I will drop the air in the system and verify I have the clearance to do the same.

[Norm Green]

Another question regarding tire purchase using the Monaco International Plan.  Has anyone used this plan in the Bend area and if so, what dealer did the use?  How about the Eugene OR area?  Thanks!

[LEAH DRAPER]

I would be interested in the Bend area also, but I couldn't find any participating dealers.

[Steve Huber]

The Michelin Web site shows any dealers south of Bend/Eugene but none are shown as participating in the Advantage program.

http://locator.michelintruck.com/default.aspx?type=rv

Steve

[Joel Weiss]

The Michelin Web site shows any dealers south of Bend/Eugene but none are shown as participating in the Advantage program.

http://locator.michelintruck.com/default.aspx?type=rv

Steve

I'm not sure what buttons you checked on the Michelin site, but for me it showed several in the Eugene area.  Use the button for National Accounts/Advantage Program.  Any dealer who handles national accounts is used to putting tires on trucks owned by the big trucking companies; the paperwork for theirs is essentially the same as what we have for the FMCA/Monaco Advantage programs.  The dealer I used in WY had never had a Monaco Advantage sale before but his people knew exactly how to handle it.

[Steve Huber]

Joel,
Good catch.I was using hte RV tire button.
Steve

[Jay and Raylene Todd]

Norm,

Is there any specific reason you don't want to reduce the load on the tag? The reason it is adjustable is so that you are able to shift the load on various axels in order to properly distribute the load. Think of the drive axel as the balance point, changing the pressure exerted on the tag shifts weight forward or aft. Increase pressure on the tag and the tag weight goes up, more weight moves to the steer axel and off the drive axel. Reducing pressure on the tag reduces the weight on the tag and steer axels and increases pressure on the drive axel. You have plenty of allowable weight allowance on the drive axel to shift the weight and bring the steer axel down to a weight the tires can support without having to change tire sizes etc. My overall weights are similar to yours but I am only carryiing about 5800 lbs. on the tag.

As others have said, be sure to weigh each tire grouping individually as well as together so you can properly balance the load. When you are done you should have weights for steer axel left, right and total, drive axel left right and total, tax axel left right and total. We have found that we can generally obtain all of these at a closed weigh station (in at least WA and OR a closed station still has the scales and indicators active). Drive down the center for total weights and then far enough to each side so that one set of tires will be off the scales. If the pavement to the sides is not level so the coach is not level when getting the side weights, go find another scale that is level.

Once you know where the weights are, you can change your pressures for the tag right there at the scales and make sure you are keeping all of your axel weights within limits.

[Tom and Pam Brown]

Reading the previous posts causes me some pause.  Individual weighs for each wheel position? The only way to change those are by moving stuff around. Not many options there with storage areas being fixed. With independent air bags there is absolutely no need to worry about 200-300 lb differential unless it exceeds the axle limit.
My only thought would be to decrease the pressure on the tag to reduce front axle weight.  The tag is designed to take weight off the drive axle and distribute it between those two axles.  The unintended consequence is adding weight to the front axle.  Since no coach I know of has a on board weighing system  (yes they do exist) I would weigh the coach as normally loaded and weigh each axle and react accordingly.
Concrete trucks and tankers that haul fluids constantly have shifting loads.  If they can make it without issue why is our coach any different? They are not.
My only suggestion here is not to over think issues. It causes unnecessary worry and expense.
Just my opinion.

[Tom and Pam Brown]

Sorry forgot,

Some drivers weigh 120 lbs. some weigh 350 lbs.  what could be done to help shift this weight differential?
Nothing! These things are engineered by the axle manufacturer to accommodate such differences. We do not have t as long as the weight does not exceed the TOTAL axle weight.

[Marty and Suzie Schenck]

Tom, You are correct that we are really not able to shift weight from one side to the other and the axle is OK if total weight does not exceed the axle rating. Some coach's come heavier from the factory side to side. Meaning the side that has the batteries or a washer/dryer or a granite counter top can weigh as much as 750lbs. more than the other side. In this case you would want the tires to be inflated to proper preassure of the heaviest side and not the lower pressure of the light side. It is much safer to have the lighter side over inflatted rather than the heavy side under inflatted. My 02 Thunder is 580lbs. heavier on the right rear (battery side) than the left rear but my total axle weight is about 20lbs. under the 21,000lbs. axle rating. If you check with tire manufacturers tire pressure charts they should confirm this method of tire pressure checking. Marty

[Tom and Pam Brown]

Marty,  you are right tire pressure may be affected.  However, my opinion is to stay 5 lbs. within the max pressure.  The fact that when you turn one way or the other  you will load the tires past the weight capacity. As top heavy as these things are it just makes my simple mind comfortable.  
Like I said in the previous post, I just do not want people to over think or worry about this issue.