Welcome, Steve and Gail. Sorry I missed your original post - we've been pretty busy moving into our coach in preparation for our full-time adventures in two weeks.

Your wheel arrangement is something like this:

front of coach
0 0 steering axle



00 00 drive axle
0 0 tag axle
rear of coach

The tag axle is there to support some additional weight. I suspect that what you are looking at is a Class C motor home. That is a motorhome that is built on a van chassis, an E350 or E450 in your case. Many Class C rigs are pretty close to gross weight when empty, so manufacturers started adding the tag axle to help out a bit.

As Mike said, the sway could be due to any number of things. How much experience do you have driving large vehicles? If you are fairly low-time, you may be looking at normal behavior of a high profile vehicle in wind. You will soon learn to get used to that, and slow down when it is windy. On the other hand, if you are pretty experienced with high profile vehicles you may be looking at something with a problem.

If you haven't given up on the rig, you can do a few things to check it for yourself. One, make sure that all eight tires have the proper pressure in them. Unless you find some written information to the contrary, use the gross axle weight information and the Michelin pressure guide. That will get you somewhere in the ballpark. Two, see if you can SAFELY check the shock absorbers for leaks. The old bounce test doesn't work well on heavier vehicles, but if you can make it bounce that may be part of the problem. Third, see if you can weigh the rig. You want weights for each axle (steer, drive, and tag) at a minimum. If you can get individual wheel weights that is even better. Compare those weights you get to the gross axle weight rating. See if you can load the rig in such a way that each axle is loaded to about the same percent of capacity.

Good luck.