[kyleb]

I haven't noticed my tag tires skidding - except on really hard panic stops -- which are rare.

The air bags on the tag are much smaller than the drive bags. The tag drums are the same as the steer axle. The tag brake chambers are smaller than the drive axle chambers.

I went to a QT that has a certified scale & had it weighed, was cheap & their scale would weigh all 3 axles individually.
Front axle - 12k
Drive axle - 20k
Tag axle - 5k
I don't remember the tag pressure. . . .

I would suggest increasing tag axle pressure until you get 12,000 to 12,500 lbs on the steer. That will give you maximum traction & stability.

[Fulltiming]

My 1992 has not had any issues with the tag axle brakes locking but I haven't been in a situation where I had to stomp the brake pedal to the floor although I have had some high pedal effort stops. I have weighed the coach at various times with the tag axle pressure from 20 psi resulting in only 5180 pounds on the tag to 45 psi with 9150 pounds on the tag. I typically run it with about 40-45 psi on the tag. I do not pull a trailer, I tow a PT Cruiser four wheels down. To minimize weight variability, I try to weigh with the fuel tanks as full as possible and try to travel and weigh with the wastewater tank empty and the water tank carrying about 40-50 gallons of water in tank plus the 20 gallons in the water heater.

[77newell]

Given the repeated times you've had the brakes examined and been told they are perfect, I would assume that they are just that and the problem is elsewhere. So the problem is either inadequate weight on the axle or the relay/proportioning valve is putting too much pressure to the cans. If playing with the air bag pressure doesn't make a difference then the valve is the problem.

Since the drums and the cans are the same as the drive axle there has to be some down regulation of the pressure to the cans compared to the drive axle. While it would be difficult to do, if you tee'd in a a pair of pressure gauges to the input to the drive and tag axle cans you would know how the pressure compares. On the relay valve on my 93 coach rear axle there is a port that I tapped into for the brakes on the towed that you could use for test purposes. There should be a similar one for the tag axle.

[Brad Townsend]

I found cat scale records from  two different dates.
11-8-2010
steer axle 12240 lbs
drive axle 23380 lbs
tag axle   14980 lbs total 50600 lbs

4-19-2017
steer axle 11140 lbs
drive axle 29820 lbs
tag axle    10820 lbs total 51780. 

Difference steer 1100 lbs
Difference Drive 6440 lbs
Difference tag    4160 lbs

 These measurements were made with the trailer hitched. I know that there would have been more tongue weight on the trailer on the last weighing by about 400 lbs. Not sure of the tag axle dragging issue in 2010 but looks like at present I could afford to put more weight on the tag which would put more on the front. The coach should have had full fuel and water tanks when weighed. Another point to consider might be that I had a bad air leak, not sure if that would effect the tag braking.
The 2010 date I don't think I had the Anderson weight distribution hitch installed yet, but it was at the 2017 weighing. Currently I am thinking about not using the weight distribution hitch and add a bit more air but not sure how much. Suggestions??

[Brad Townsend]

Correction trailer tongue weight would be around 1400 lbs.

[Richard]

Brad,

What kind of tires, load range? and what inflation are you running?

Also, I am trying to understand the difference between your weights and Kyle's. 1400 lbs on the hitch does not explain the drastic difference in your rear weights.

[Brad Townsend]

Michelin X load range single 7160 lb double 6610 lbs size 24.5 running air front 120 all rears are at 110 lbs all tires are the same make and model.

[Fulltiming]

Since your tag, like mine, is rated for 10,000 pounds, I would think you would want to try to keep it as close but under 10,000 pounds with the trailer hooked up. That will put the most weight on the tag that Rockwell specified. Since I haven't had an issue with my tag brakes, I haven't examined the air brake circuit in the rear to see if there is a proportioning valve to the tag air brakes or not. Obviously we do have a gauge and valve to control the air bag pressure on the tag axle on both of ours which was not used after about 1993 or 1994.

[Brad Townsend]

What is the pressure on your tag Michael?

[Fulltiming]

Right now it is 40 psi.