From experience, 20-inch wheels are not an off-road consideration. I am surprised Toyota offered them on this vehicle: snow chains and 20-inch wheels are a significant problem. Plus, the low-profile side walls are an issue for any alternative terrain. Eighteen inches is the max. If you look at other manufacturers that offer extreme off-road vehicles, you will see some come with 16-inch and 18-inch wheels. Get a second set of wheels and put the winter tires on them. The Ford Raptor uses 18-inch wheels with its 37-inch tires. In contrast, Land Rover and other luxury SUVs use larger wheels since they know the car will never see adverse conditions. But if you look carefully, some Land Rover / Range Rover and Lexus, for that matter, offer off-road versions of a specific model that will have 18-inch wheels with more aggressive AT tires.