Tire inflation?

[GKW]

Originally Posted by bdickson

My sticker said 105 psi all round. I had the coach 4 corner weighed and looked up the tire manufacturers charts. Using the heavier weight on each axle I'm running at 90 front 95 rear. I then installed Crossfires on the duallies so the pressure in each pair of tires is the same. Setting each side of the coach to different pressures does not sound safe. When I check my temperatures after a run, left and right sides can have a big difference, but that is due to the direction of the sun hitting the rig.

I have also checked temperatures from side to side on our coach and noticed a substantial difference. The crosswind you frequently encounter will have an effect as well as chassis alignment, individual tire characteristics, and also exposure to the sun etc.I find running 105 psi on all tires is a good compromise pressure for ride, handling, and load.

[gemert]

I know this is an old thread but it was a good one but I have questions and you all seem to be pretty knowledgeable.
I'm new to a Class A. I had a small 5er for 15 years and in my ignorance never worried about tire pressure and only had one tire go in that amount of time.
Now I am the proud owner of a 4o ft Beaver with tag axle.
Have not been able to find a place to weigh all 4 corners yet.
front weighs 13040 and the rear weighs 22520.
How would I balance the tire pressures?
Tires are Hankook 275/70R 22.5.
Thanks in advance

[Steve Ownby]

Originally Posted by gemert

I know this is an old thread but it was a good one but I have questions and you all seem to be pretty knowledgeable.
I'm new to a Class A. I had a small 5er for 15 years and in my ignorance never worried about tire pressure and only had one tire go in that amount of time.
Now I am the proud owner of a 4o ft Beaver with tag axle.
Have not been able to find a place to weigh all 4 corners yet.
front weighs 13040 and the rear weighs 22520.
How would I balance the tire pressures?
Tires are Hankook 275/70R 22.5.
Thanks in advance

Hey Jerry,

Thanks for your service.

Need a little more info.

That steer axle is pretty heavy for that tire size. There should be a placard on the wall around the drivers seat detailing the tire size and the GAWR for all three axles. As currently configured, even if you are pretty well balanced side to side on the steer axle, you need about 120 psi in those tires.

If possible, you need to know how your rear weights breakdown between the drive axle and the tag. The reason I say this is if the tag is loaded pretty heavy and the drive axle is down around 17k, you can reduce the down force on the tag axle which will get some weight off the steer axle and the tag and add weight to the drive axle.

The other think you can do when you need to replace tires (how old are yours by the way) is explore going up a size. A 275/80 tire came carry slightly more weight at 110 psi than your current 275/70 at 120 psi.


Steve Ownby
Full time since '07

[gemert]

Originally Posted by Steve Ownby

Hey Jerry,

Thanks for your service.

Need a little more info.

That steer axle is pretty heavy for that tire size. There should be a placard on the wall around the drivers seat detailing the tire size and the GAWR for all three axles. As currently configured, even if you are pretty well balanced side to side on the steer axle, you need about 120 psi in those tires.

If possible, you need to know how your rear weights breakdown between the drive axle and the tag. The reason I say this is if the tag is loaded pretty heavy and the drive axle is down around 17k, you can reduce the down force on the tag axle which will get some weight off the steer axle and the tag and add weight to the drive axle.

The other think you can do when you need to replace tires (how old are yours by the way) is explore going up a size. A 275/80 tire came carry slightly more weight at 110 psi than your current 275/70 at 120 psi.


Steve Ownby
Full time since '07

Checking the placard in my coach should have been first thing on the list but when I picked it up I didn't know the weight so I had all tires set at 125. Remember I am new at this so I am unfamiliar with a lot of this...for now.
GVWR=42800
GCWR=52800
FGAWR=12800
RGAWR=20000
How do you adjust the tag? Also does ride height enter into this?
As far as bigger tires go, when the air is dumped the front wheels pretty much fill the wheel well. It didn't look like there was an extra inch in there. But to be honest that was just an observation before I weighed the coach so I'm not really sure. Oldest tire had a date in 2010 stamped on it.

[Steve Ownby]

Originally Posted by gemert

Checking the placard in my coach should have been first thing on the list but when I picked it up I didn't know the weight so I had all tires set at 125. Remember I am new at this so I am unfamiliar with a lot of this...for now.
GVWR=42800
GCWR=52800
FGAWR=12800
RGAWR=20000
How do you adjust the tag? Also does ride height enter into this?
As far as bigger tires go, when the air is dumped the front wheels pretty much fill the wheel well. It didn't look like there was an extra inch in there. But to be honest that was just an observation before I weighed the coach so I'm not really sure. Oldest tire had a date in 2010 stamped on it.

So it looks like you are 240 pounds over the steer axle weight rating and if you can shift some of that back to the drive axle that would be a good thing. Obviously 240 pounds is not a huge deal but if you can get the weight down some you can back off the tire pressure a little.

If your Beaver is a Monaco produced coach there should be an adjuster mechanism back in the engine compartment on the drivers side. It has a air pressure gauge and a knob on top that locks in one position and unlocks and adjusts the air pressure in the other position. You should also have a tag lift switch at the drivers console.

1. With the engine running raise the tag and then lower it to stabilize the tag pressure.
2. If the pressure gauge reads over 40 psi, turn the knob until the pressure reads about 30 psi.
3. Raise & lower the tag again & recheck the psi.
4. Go have the axles weighed again.

The goal is to get the weight on the steer axle down below the FGAWR. If possible, get a separate weight for the tag. Then you can finalize your tire pressures.


Steve Ownby
Full time since '07

[gemert]

Thanks Steve. I'll do it.

[Dr4Film]

Originally Posted by gemert

How would I balance the tire pressures?
Tires are Hankook 275/70R 22.5.
Thanks in advance

Here is a form that explains everything.

Remember also that besides tires that have maximum inflation psi, the wheels do also.

You will need to find the inflation tables for the specific tire and model of Hankook you have on your RV.

Dr4Film ----- Richard

[gemert]

Originally Posted by Dr4Film

Here is a form that explains everything.

Remember also that besides tires that have maximum inflation psi, the wheels do also.

You will need to find the inflation tables for the specific tire and model of Hankook you have on your RV.

Dr4Film ----- Richard

That PDF is a great resource. Thank you