Well, if you add that you check the tire pressure (for the load you carry) every time before you roll down the road, I would say you should easily get 10 years out of your tires. Oh, let me qualify that to also include that you know they've been properly checked since they were installed on the motorhome. I never covered our tires, just didn't see the need seeing as the rig is usually here in the NorthEast.
Our rig came with the Michelin XRV's and I got 12 years out of them, about 30K miles, give or take. I replaced them because we had two long trips coming up, one through the summer heat, so I decided it was best to change them out. I went to the Toyo's. No complaints. Despite all of the stories I read about the XRV's, ours served us well. I might've even pushed them another year or two if we were sticking to local trips.
On my Michelin's, I checked tire pressure every morning before travelling and hit the tires with an IR temperature scanner at rest stops. So I knew they were always treated right, and I never ran over curbs or road hazards of any serious nature. KNOWING those types of things gave me confidence to push things a little past the 10 year point.
With the Toyo's, I took the savings between them and Michelin's and bought a TPMS system for the moho and the dinghy. Again, money well spent, in my opinion. Now with a push of a button, I know all of the tire pressures are good and ready to go.
~Rick