Typically, the manufacturer or even the dealer overinflates the tire upon delivery. As stated above, check your pressure first. There are many add on products, but they can cost you a fortune by the time you're done.
When you drive, it feels like the front of the coach is requiring a lot of steering input. It's actually the rear end moving around on the springs, side to side. If you read through threads here, you'll find that many have the most success with a rear track bar.
I would suggest that you start with the free stuff, such as weight and tire pressure before adding any aftermarket products. If you decide to buy something like the rear track bar, buy one item at a time and see how it works.