I recently sold a Class A and I received a lot(30+) of phone calls from potential buyers. About 2/3 of them asked about the age of the tires.
Sure you could remain silent and hope that your buyer is one of the few people that is ignorant about tires on an RV. On the other hand, if someone knowledgeable calls and asks about your tires, they may just assume that you have allowed everything else on your RV to age out, which is why you are now dumping it.
I would still address the tire issue in your ad description and increase your sales price to negotiate with a tire replacement.
My RV sold at full asking price to the second person to look at it and we negotiated about the tire issue to close the deal.
If you are going to write a sales ad listing all of the good things about your RV, why not list the tire replacement as a positive item and price your coach accordingly?