Rough Riding P32

[Isaac-1]

Can you tell us the brand and model of tire, perhaps someone here as experience with them

[Mudfrog]

Originally Posted by Vroom

Mudfrog,
You maybe on to something with tires. The tires on my rig were purchased by the previous owner. They are new with only a few hundred miles, Made in China, 12 ply rating, 5 steel cord tread, regroovable, 1 ply steel cord sidewall. In your estimation would this make up a hard tire? Thanks Doug.

Not a tire expert here for sure, just wanted to tell of my experience.

The oem Michelins were 225 70/19.5 load range F tires. I may be comparing apples to oranges but the two tires I installed on the front a few years back were load range G Sailuns. That's what the dealer had and recommended. I would say it's very possible that load range F Sailuns would have rode better than the Gs that I had. Made sure to go with load range Fs when I bought the Bridgestones. They do ride a bit firmer than the Michelins.

[Vroom]

Two pieces of information I neglected to put in my original tire description-
Load range F
Dynatrac ST-990

[Isaac-1]

What pressure are you running in the tires? and what is the GVWR of your chassis

[Vroom]

The GVWR is 15,000 and I'm running 80 psi in the front tires and 90 psi in the rear tires per the Federal Certification Tag posted in the vehicle. Thank you.

[Isaac-1]

You really need to get it weighed and use a tire manufacture inflation chart like https://www.rvsafety.com/images/pdf/...ionrvtruck.pdf I have a 17,000 pound GVWR P32 chassis and run 80 psi rear and 75 psi front, which still allows for over max GVAR both front and rear, as well as being above my actual travel weight.


p.s. I had new tires put on in February, and told the tire shop how much pressure to put in the tires, they ignored me of course and put 90 psi in all around, and the 20 mile drive back to the storage shed was awful, it is bumpy and the coach was all over the road, before driving it the next time I lowered the pressure down to the correct range, and it was a night and day difference.

[Mudfrog]

Originally Posted by Vroom

The GVWR is 15,000 and I'm running 80 psi in the front tires and 90 psi in the rear tires per the Federal Certification Tag posted in the vehicle. Thank you.

Ours is the 15,000 lb chassis. The placard by the driver seat states 75 psi at all four corners. The tire inflation chart shows that pressure will cover the gvwr. Seems strange your placard shows 80 and 90.

[LETMGROW]

My placard reads Rear 90# front 80#. 2002 P 32 17,000 GVWR
I run Michelin XZE front tires and Firestone FS 560 LRG rear tires. All are 225 70 R 19.5 Load range G.
We travel a little light so I drop the tires 5# front and rear. 50# in the front spring air bags. We make one trip yearly when we load heavier for a longer stay and I add the 5# back to the tires all the way around. At that point in time we are also traveling with a full fresh water tank.

[Vroom]

Thanks to everyone that offered up some great suggestions. I tried dropping the bag pressure to 70#, dropped front tires to 75# and rear tires to 80#. It did improve the ride although on a very sharp right turn I heard the right front tire come in contact with the right front wheel well flair. I'm guessing it would happen on a sharp left also. I'm thinking it will only get worse if I go any lower on the bags.
I usually travel about 60 to 65 in the slow lane. I noticed when I'm being passed on the left, even by a small car, I'm getting a noticeable front end push to the right. Serious side draft. Anybody else feel this.
Thanks for reading my post, Doug.

[Mark_K5LXP]

Originally Posted by Vroom

Serious side draft. Anybody else feel this.

Cars are one thing, just wait until you get passed by an oncoming semi on the highway. A panhard bar can help with some of that and isn't too expensive. You're not going to turn a P32 into a Prevost so from my perspective it's all about managed expectation.

Mark B.
Albuquerque, NM

[Vroom]

Mark B.,
Well said. I'm starting to understand that more and more with every post. Its a real learning curve, no pun intended.
Thank you, Doug.

[BA-in-Mich]

One thing about the front air bags, when you change the air pressure you are changing the steering geometry. When you have the front end aligned you need to set the pressure at a particular PSI and then maintain it.

[LETMGROW]

Originally Posted by BA-in-Mich

One thing about the front air bags, when you change the air pressure you are changing the steering geometry. When you have the front end aligned you need to set the pressure at a particular PSI and then maintain it.

That is correct. Find the pressure the coach looks level (with the coach loaded up and ready to travel) and rides the best then take the coach for an alignment.
There is a ride height specification your alignment guy should have. Check with him. We all load our coaches differently so the pressures may vary from user to user. The condition of the front springs will play into pressure adjustments as well.

[Mark_K5LXP]

I think the air bags are more about suspension compression rate than height adjustment. Just as a data point, I measured a 5/8" height difference between 0 and 90PSI in my air bags. Maybe others will see a greater difference but I wouldn't think 5/8" would affect steering geometry and hence alignment to any significant degree.

Mark B.
Albuquerque, NM