FWIW I tended to get water collecting inside the spare wheel, at the bottom edge of the wheel where the tyre wall was sitting on the surface. I solved this by taking the wheel off and glueing a small black plastic shim across the position that the tyre wall would sit. Shim is about 4-5mm thick and about 70mm long by 20mm wide. The water now drains down either side of the shim when the tyre gets water in the centre.
