The general recommendation for storing your coach, especially on a concrete floor, is to use something waterproof between the tires and the floor. I have used leftover pieces of vinyl flooring for several years now but they are falling apart. I got an email a couple weeks ago that Flor was having a sale, 25% off, on their carpet tiles. We have them in a couple places in the house and they are very nice so I was ordering some for my office. I noticed they have an outlet shop so I checked it out and they have random tiles for $1.00 each. These have a robust waterproof base with carpet on top. The discount price was $0.75 each for six tiles (0.5 meters, about 19", square). They came today. Now the coach is sitting on some pretty fancy waterproof carpet squares.
Outlet - Carpet Tiles (http://www.flor.com/carpet-tiles/outlet)
Expensive but helps with the flat spotting. As good as you are with wood, 6 custom blocks would be nice.
Amazon.com: Auto Care Products 95210 Park Smart Large Vehicle Tire Savers... (http://www.amazon.com/Auto-Care-Products-95210-Vehicle/dp/B01D9NK36A/ref=sr_1_8?s=automotive&ie=UTF8&qid=1477697731&sr=1-8&keywords=flat%2Bstoppers&th=1)
I guess they are pricy. $240+. My six squares were $4.50. I always inflate my tires to max psi for the storage period. Adjust as required before we head south.
I am somewhat ignorant to this problem... the last tire I had that developed a flat spot was a bias ply on a trailer. Our big truck tires flat spot? Or dors this also help with something else?
It depends on how long it sits. and how heavy the load is. Do a Google search on " tires sitting too long"
A few months at full pressure and most tires on coaches will not get flat spots. We looked at a coach when we were shopping that had sat without moving for more than 18 months at unknown pressures. Michelin suggested replacing the tires.
Isolating the tires from the concrete or asphalt or ground prevents moisture migration to the tires and as it was described to me the wheels and suspension parts. It is easier on the rubber and reduces rust and corrosion. It is mostly to protect the tires. Some folks use plywood. Probably better than nothing but a true moisture barrier is most likely better.
http://www.michelinb2b.com/wps/b2bcontent/PDF/RV_Tires_Brochure.pdf#page9