Tire pressure question

[Garrett]

I just replaced my tag axle pressure gauge. Old one gauge was broke so no idea where PO had it set. I am going to CAT scale to weigh. I can get all 3 axle weights but none of the CAT scales around am I able to do corner weights. I am scheduled to have individual tire weights done in Phx at NIDRV on the 16th. My question is once I get my proper weights set on each axle I can divide the weights to get axle weights to figure tire PSI. Knowing that that wont give me weights considering uneven loading how much PSI should I add to each tire to be safe until I get to Phx? (1300 miles)

[vito.a]

I'd start with 40psi in the tag axle pressure regulator. 

115psi in the front tires, 100psi in the drive tires, and 90 in the tag tires.  

That should get you close.  

When you get to the Cat scale your goal is to load the tag axle enough (by increasing or decreasing the tag pressure regulator) to keep the drive axle under it's limit without putting the front axle over it's limit.  

Really watch the front axle weight as these coaches tend to run very heavy on the front.  

[Garrett]

When I adjust tag axle either up or down do I need to drive it a bit before I re-weigh or no?

[Ivan K]

You don't need to drive but deflate all the bags some and let them go back to ride hight.  I think the manual has a writeup on it, it might say to do it couple times up and down. I would have the engine running too in case there are some leaks, so the ride high adjustment is active with plenty of air as if on the road.

[Ivylog]

40 is a good psi for the tag’s airbags unless you’re putting a fairly heavy trailer.

I’d say Vito’s are already 5 more than necessary so good for any unbalance side to side. No, you don’t need to move if you change the psi a small amount.

Edited April 1 by Ivylog

[96 EVO]

Just inflate your tires to the placard pressures next to the drivers seat until you can run across a scale.

Those pressures will be good right up to your axles fully loaded.

Like others have said, 40psi on your tag regulator is a good starting point.

[Garrett]

Appreciate the help!!

[Frank McElroy]

On 4/1/2024 at 7:17 PM, Ivan K said:

You don't need to drive but deflate all the bags some and let them go back to ride hight.  I think the manual has a writeup on it, it might say to do it couple times up and down. I would have the engine running too in case there are some leaks, so the ride high adjustment is active with plenty of air as if on the road.

Like Ivan said, when weight coach it's important to have the engine running. The system must also be in travel mode.  If the system is off, your axle weights will not be accurate.

[Paul J A]

On 4/1/2024 at 4:39 PM, Garrett said:

When I adjust tag axle either up or down do I need to drive it a bit before I re-weigh or no?

I would. Complete the process once and done.

[Garrett]

Ok. I’m at CAT scale. 1st weigh is attached. Full water, full fuel, tanks empty, 115psi in steer, 100 in drive & 90 in tag. Coach running 
don’t feel I can lower tags to much more due to from axle weight. 
thoughts?

[96 EVO]

What's your steer axle GAWR?

[Garrett]

Steer 15260

drive 20000

tag 10000

 

15160 on steer. Typo

[96 EVO]

Yeah, your about there.

You could maybe add a couple of psi to your tag regulator, or leave things be.

[Garrett]

I’m thinking I’ll leave it till I get each tire weighed on 16 th. I will only have water at about 30% while traveling so will drop a bunch off drive axle. 
thx!!

[Frank McElroy]

I'd add about 4 more psi to the tag and get a reweigh.  This will give you a good idea of how much of a change in the tag PSI effects the drive and steer axles.

[Garrett]

Will do. Thanks!!