Forum Discussion

CA_Traveler's avatar
CA_Traveler
Explorer III
Aug 09, 2014

Tire Pressure 6 Corner Concerns

Here’s the weight on one of the free Oregon scales which appeared to be mostly level off to the side. Note that I measured the total and right side and the left side is the difference.

Front right 7,000 left 7,550, total 14,550
Dual (both tires) right 10,750 left 9,250, total 20,000
Tag right 2,000 left 2,850, total 4,350

I’d certainly like the side to side weights to be closer. The tag doesn’t have enough weight which is consistent with its much less wear than the duals at 31K miles.

Continental HSR2 295/80R 22.5 on the front which is a much better riding tire than the replaced Badyears. Planning to replace the rear Badyears in a month.

Continental Load Inflation Table maximums: Single 7,830, dual 6,945. I’m planning to add 2,000 lbs to the adjustable tag weight which will reduce the dual weight. I estimate this will add about 325 lbs to the front. The tag suspension is currently set to 30 psi and can be increased.

Anyone have an idea how tag suspension psi relates to tag weight or other suggestions?
  • Have you thought about going to a rally, like an FMCA rally? They usually have folks there who can do a 6-point weighing of your coach, which should be more accurate than using a truck scale.
  • Also the tag/dual separation is 41" which means the dual and tag weights are on the edge of the scale. I can't help but wonder how accurate the truck scales are near the edge.

    I had no way to measure the ground vs scale level so I should probably just use the total axle weight until I can get accurate side to side weights. I'm also aware that there are some inconsistencies in the numbers I posted.

    In several weeks I'll be at another ODOT scale and plan on more measurements including tag adjustments.
  • I'm calling ODOT to have them level the next scale I use. :)

    But I have a starting point to get more accurate weights and make any tag adjustments. I appreciate the input.

    I'll call Monaco to get the ride height measurements and see if they have a factory tag psi setting.
  • Yikes, Front GAWR is 14,600. Guess DW will have to ride in the rear. :B
    Dual 20,000 and tag 10,000.

    It will be awhile before I can get and check the ride height adjustment. I can say that when on level ground the rig is very close to level. ie Very minor or no leveling of the rig. I've verified that the refer is level when the leveling system indicated the rig is level.
  • If the ground on the sides of the scales was not level with the scale itself, it is unlikely you have good left/right numbers.
  • Mandalay Parr wrote:
    Increasing tag psi should increase the load it is carrying.
    While decreasing the dual and increasing the front. I'd like to have some idea of the relationship between the variables.

    I plan to make the adjustment at a Oregon scale and document the axle weight changes for the tag psi change. I'm thinking to adjust psi, weight total axle weight and repeat as necessary. When that looks good do a side to side check.

    The prior weight was measured with full fuel, water, propane and cargo. The fuel tank is directly behind the front axle and the water tank is behind the fuel tank. The 830 lbs of water can be transferred to the holding tanks which are directly in front of the dual axle.

    It's not beyond consideration that the scale was not accurate especially side to side.
  • Please post your GAWR's for each axle. More weight on tag also puts more weight on front axle and removes it from the drive axle. Until you know how the front axle is loaded (percent of GAWR)it is not reasonable to make adjustments.

    Ideally, you want the same percent of GAWR on each axle.

    As far as left/right imbalance I would check ride height. Actually, anytime you are fine tuning weights/tire pressures, it is a good idea to check ride heights. If one of the two ride height valves on the drive axle is mis-adjusted, it can give you a lot of left/right imbalance-- think of how many of your really strong friends it would take to raise one side of the rear of your coach even 1"!