You will just have to measure the wheel wells on your particular coach. Also consider the dual spacing on the rear axles, since the larger tires may rub against each other if the offset isn't sufficient.
However, I would not assume larger tires will make it ride any better. You might be able to run at a bit lower pressure (psi), but that doesn't necessarily improve things. There are numerous reasons why one coach might ride differently than another, si the difference in tire size is not an automatic answer.
2004 American Tradition; 2013 Buick Verano
Homebase in the Ocala Nat'l Forest near Ocala, FL