Is A New 2018 Still New?

I'm looking at a Winnebago Class A floorplan I like and 2 or 3 dealers still have new units from 2018 in that floorplan. Is that a problem? For example, I have read that RV tires will need to be replaced after 3 or 5 years (I don't remember exactly) even if they don't have many miles on them. Are there other systems in a Class A motorhome that will decay from sitting on a dealer's lot for over a year? Would you be hesitant to buy a new 2018 Class A motorhome? The prices are below the best prices for 2020 models, and I like the upholstery better on the 2018.