Tire Pressure - Help

[Rspitler]

Originally Posted by oakcreekeric

Just wanted to add some closure to this thread..

After thinking long and hard, I decided to lower my pressure from 90psi to 85psi - I could not be more happy with my results. I felt the rig was still on par with all the drive-ability aspects.. but really softened up the concrete expansion joints and small pot-holes..

All in all.. I felt this was a good compromise between fuel mileage and comfort, as I didn't notice any discernible difference in my fuel mileage, and I felt I greatly improved the riding experience..

Thanks to all those who replied and offered advice and suggestions.. THANK YOU !!

Still happy at 85?
I had mine inflated to 98 and really feel the joints!
Gvw on 32Sa GVW only 24000 lbs so I’m looking at 85 lbs for next trip!

[Rspitler]

Gonna get corner weights next trip as well

[oakcreekeric]

Originally Posted by Rspitler

Still happy at 85?

Yes, very happy with 85 - we put close to 3000 miles on the rig and everything was fine.. I immediately noticed the difference in the concrete expansion joints in the roads.

I think that's the sweet spot for my rig.. I would love to get a 4-corner weighting done too.. but I'm not sure who does that in my area..

[Crasher]

Originally Posted by oakcreekeric

Yes, very happy with 85 - we put close to 3000 miles on the rig and everything was fine.. I immediately noticed the difference in the concrete expansion joints in the roads.

I think that's the sweet spot for my rig.. I would love to get a 4-corner weighting done too.. but I'm not sure who does that in my area..

When I got my first four corner weigh, it was at an FMCA rally in Gillette, WY. It was way out of whack with the FR 1000#heavier than the FL. After I had the ride height valves checked and adjusted, I wanted a reweigh. I called the WI State Highway Patrol Vehicle inspection office for help. The came to my home, blocked the street with his suv and we did a six position weigh in the middle of the street with his portable scales. I adjusted the tag bag pressure and another weigh. All was well. There was no charge for the service and he was happy to help out. He said it was my tax dollars at work. There must be an office in the Milwaukee area that could help you, even if you had to go to their office or state scale. You can be assured that their scales are correct.

[Mudfrog]

Originally Posted by IggyTech

Yes front axle dive by 2 and rear dive by 4 .
I see 90 psi all around by your information and charts




Here is what I just posted a few days ago about my weight and tire pressure.

http://www.irv2.com/forums/f258/are-...re-400292.html

Let's see, 75psi gives a capacity of 3645 lbs a tire. Makes the two up front good for 7290. That's 570 lbs more than the actual axle weight.

Go with 75 psi in rears and the capacity is 6630 per side. Total capacity of 13260 lbs, 1880 lbs above the actual axle weight. I agree that since a 4 corner weight didn't take place, it wouldn't hurt to move up to 80 psi to cover a probable heavier side.

However, 90 psi is just plain overkill and as the OP eluded to in his first post, was giving him a harsher ride than he wanted. He came back to let us know the drop of 5 psi helped. I'm confident that if corner weights are had and sides end up being fairly even, that dropping a few more psi will give an even better ride.

[Sherpa Vern]

Originally Posted by oakcreekeric

Hello,

I'm about to embark on our vacation to Yellowstone. In preparation for the trip, I had my rig weighed at a local CAT Scale. Below are the numbers and relevant information on my RV - I'm hoping someone could help with an "optimum" tire pressure..

RV data -

GCWR - 26,000
CVWR - 22,000
GAWR (front) - 8,000
GAWR (rear) - 15,000
Michelin XRV Tires

CAT Scale Readings

Steer Axle = 6,720
Drive Axle = 11,380
Gross Weight = 18,100

I did this fully loaded with fuel and water, as that is how we travel.

I currently have my tire pressure set to 90psi - I'm just looking to tap into the collective wisdom of this group to see if I should be at something different to optimize my ride comfort and fuel economy.

Thanks

This is an easy "fill in the blanks" calculator that gives good information about your question and more, to include drop down lists that refer directly to your brand and size tire.

4 Corner Weighing - Individual Wheel Weights

Edit - I filled in your information and got the following results:

Front - 75
+ 5% - 78.8
+10% - 82.5

Rear - 70
+ 5% - 73.5
+ 10% - 77.0

After corner weighing, you will get different results and the chart will use the heaviest end of each axle for the pressure to be used on both ends of each axle. It will also show any imbalance to help to with any shifting of loads to better balance each axle.

Before corner weighing is done, it might be prudent to use either the 5% or 10% increase in pressures to ensure enough pressure to compensate for a likely imbalance on each axle.

[Domo]

Originally Posted by oakcreekeric

So... I'm waffling between 75 & 80 psi... I'm really having a hard time going lower than 80psi.. I clearly see what the chart says.. but I worry about side-wall integrity with such a low psi..

I've got a couple days before we leave (7/19).. I'll need to figure this out before then..

Thanks for all the replies, very much appreciate the input..

Don't you think the tire manufacturer's research teams and engineers have figured this out yet?

Seems to me they publish the charts so people will use them and get the best and safest service life out of their product -