Thanks for the info Rusty! The chassis guy here in LV said he didn't find anything alarming in the rear suspension that would cause squirming. He did mention that there was a Spartan upgrade of the rear links as some were incorrect when leavng the factory, so I have other things to find out from them as well.

Will post the results.

Tomorrow I go to the scales and see how the weight distribution is. If it is close to the tire limit I think I will change out the wheels to a wider rim and go for 245R70 19.5 LR G

I have two chassis stickers inside the front gen access door,
one says gvw = 20,000, 13,500 rear and 6500 front,
other says 18,000, 12,000 rear and 6000 front.

I think I see why the second rating, using the first one would be overloading the rear tire spec. 3305 X 4=13,220.

Let's say that your GVW is 13500 for the rear and 6500 for the front. According to the Bridgestone inflation tables, that would call for 85# in the front and 90/95# in the rear. That assumes that your axles are not overloaded. One thing I learned early in my motor home experience is that the amount of air in a tire is based on how much weight is on the axle and you don't put the maximum amount of air in that the tire is rated for. Now, if you have more weight than the axles are rated for, that's another issue. Maybe I didn't read the Bridgestone table correctly, but then you could always call them directly after you have your coach weighed.

Bridgestone (and Michelin) are only rated for 3305 LBS each in dual use. That would only allow a rear load of 13,220. At that load rating, stamped right on the tire is 3305 @ 110PSI. I believe that this is why the original Spartan chassis spec of 13,500 was reduced to 12,500. A 13,500 rating would exceed the tire rating.

I had my coach weighed and it is 12,880 on the rear and 6023 on the front. I am exceeding the revised chassis rating (of 18,000) by almost 1000 lbs. This weight was with full fuel, full propane, full water, waste tanks at a minimum, plus food and baggage 2 SOB.

I made it safely home this morning from Las Vegas, the Barth ran very well but still was tail wagging all over the place. I stopped at a RV shop for an estimate to repair the generator housing (for claims purposes) and had a discussion with the owner there, He is well known for his FMC coach rebuilding, commented that although they do not like to make tire suggestions, they have had a lot of complaints about Bridgestones and in particular, pushers, for 8r19.5 application they only replace with Michelins and stick to the 8R size.

I view of the weight of my Barth and the loading, I am re-thinking what I will do, my first thought is to seek a wider rim/wheel and replace all with 245R70 19.5 LR G. It is only a thought at the moment and further research is needed.

Will advise

Rusty:

quote:

I run the Bridgestones at 100 psi rear (10,650 lbs.), 95 psi front (5,260 lbs.)

You are much lighter then I at those weights. Just had the weight checked and it is 12,800 on the rear, 6083 on the front. At those weights I have to run 105 on the rear and 95 at the front.

I don't have a Dana 80 on the rear I have the Eaton 15040S which is much heavier unit then the Dana 80.

My over hang is 10 foot from the axle center to the rear of the chassis (not including the bumper) and 6 foot at the front not including the bumper.

I have Michelins on now and it is MUCH better, far less tail wag!

Two things I measured are the actual tire foot print at 105 lbs inflation and the speed comparison.

Bridgestones have a 1/2 to 3/4 inch longer print then the Michelins and the Bridgestones register 2 MPH less speed on the GPS when the speedometer is reading 60. This means that the Bridgestones have a slightly smaller rolling radius even thou it is advertized as larger.

Anyway, the 8R19.5 Michelins are there until I find a suitable hub to go with a 10 bolt Budd wheel and then will change over to 245R70 19.5 G rating, probably next year.