I'd just put a good coat of paste wax on the inside and outside and hope it doesn't get any worse. I think that's about all you can do besides repainting or replacing. I've not had good luck with repainting wheels in the past. They look great initially, but it doesn't last like the original baked-on coating does.
2007 T-286SR Cherry/Granola, #6236, original owner, current mileage: 9467.8 (as of 5/26/19)
1997 T-2653 Blue Denim, #5471
1979 12 1/2' MC, Beige & Avocado, #4639
Past Sunlines: '97 T-2653 #5089, '94 T-2251, '86 T-1550, '94 T-2363, '98 T-270SR