I'd suggest Hellwig Sway Bar first. It'll help you with less rocking on the campsite as well as better handling on the road.
Firestone TransForce seems to be a very satisfactory "all season" tire. So is the Michelin LTX M/S2.
Upgrades from those are Michelin XPS Rib and Bridgestone Duravis R250.
Weigh the coach, getting at least Front and Rear Axle Weights, loaded as for travel. Use those weights to set tire pressures. Also, if you're not near full axle weight ratings, the TransForce and LTX look even more viable. They ALL, even $100 cheapies, have the same rating for the same specs, but higher lines are still more durable than lower ones.
