If you have steelies you can always go to China-Mart, get yourself some $15 wheel covers and tape the holes over with high-strength gray tape. Alternatively, you can cover the wheel covers with thin vinyl sheeting. The latter approach has worked on my car for the past 10 months. It's an improvement over bare steelies. Maybe not as good as taping up the holes so it's all flush...
Here's a shot of them back when they were installed:
