Confused about tire pressures

[Midniteoyl]

Originally Posted by TheArnolds

Gary:

Today I weighted our new coach (2013 Thor Palazzo) for the first time in preparation of our first long trip to upper Michigan.
Steer Axle: 6960 (GAWR 10,500)
Drive Axle: 15,520 (GAWR 17,500)
Gross Weight 22,480 (GVWR 26,000)
GCWR 30,000

The chart behind the driver’s seat says to inflate front and rear to 120 PSI (the dealership delivered the MH to me with all tires inflated to 120 PSI per this chart).

I have Goodyear G670 RV 255/70R 22.5 16 ply installed. The Goodyear booklet provided has an inflation range of 80 PSI (S 4190 lbs/D 3970 lbs) to 120 PSI (S 5510 lbs/D 5070 lbs) and like others; I am confused as to what pressure to inflate my tires?

Referencing the steer axle as an example 6960 divided by 2 = 3480 and as you can see this is well below the 4190 @80 PSI minimum on the Goodyear chart.

If I understand it correctly I should divide the drive axle weight by 4 or 3880 per tire. Again nowhere near anything on the chart. I do not think I should be running 120 PSI all around like the way it was delivered but I do not think I should be running 80 PSI (the minimum) either?

Your opinion as to what pressure I should run would be appreciated! Other than a harder ride what would be the problem running the 120 PSI the way it was delivered and what is listed on the chart behind the driver’s seat?

Thanks in advance for you opinion!

You should be running the minimum PSI Goodyear allows, which is 80 psi. Actually, I would run 80 psi front, and 85 - 90 psi rear to decrease rolling resistance and just so I would never have to worry about more weight on one side or the other..


You DID weight the coach loaded and ready to go, correct? If not, you would need to add that weight in and adjust the PSI up accordingly.

[TheArnolds]

Originally Posted by Midniteoyl

You should be running the minimum PSI Goodyear allows, which is 80 psi. Actually, I would run 80 psi front, and 85 - 90 psi rear to decrease rolling resistance and just so I would never have to worry about more weight on one side or the other..


You DID weight the coach loaded and ready to go, correct? If not, you would need to add that weight in and adjust the PSI up accordingly.

Thanks for the suggestion! Yes, it was basically loaded for travel with 95% full fuel tank, half full water, and empty holding tanks. We may add a couple hundred pounds for food and last minute things but as light as we are I do not see this as a problem.

[Midniteoyl]

I was surprised you were so light.. Dont forget the weight of people

[TheArnolds]

Originally Posted by Midniteoyl

I was surprised you were so light.. Dont forget the weight of people

No but my DW and I only add 360 lbs and my DW will not allow me to tell how this is split.

[Midniteoyl]

LOL!

Why, 260 and 100, of course

However, that makes the front weight 7,300

[TheArnolds]

Originally Posted by Midniteoyl

LOL!

Why, 260 and 100, of course

However, that makes the front weight 7,300

Yep! you got the split right!

Even at 7300 lbs (divided by 2 = 3650) it is still below the minimum Goodyear chart weight of 4190 @ 80 psi.