If original tires, they are probably dated out by now, or close (2011 probably). Could replace the Michelins with Toyos to reduce that cost and still a good tire.
For Winnebago products always check the side roof sealant at the cove. Check it yourself or have someone competent check it. Many Dealers don't have a clue. The risk of failed sealant is the roof can peal back in a high wind and ruin your roof. Easy to avoid with the right inspection and the right caulk (not Dicor), but expensive if neglected. These guys explain it best.
Winnebago Roof Cove Maintenance