As per request, here's a Photoshop tip for noise removal that I find very useful.
Before
After
I would recommend doing the following as it does a great job at removing color noise, especially when noise removal itself doesn't do the job good enough.
1. Before even starting your pen tool selection, go to "Filter->Blur->Surface Blur..."
2. Set the radius to 3 levels then adjust the threshhold depending on amount of color noise on the cover you're working with. Try not to overdo it or it can smudge. Having some noise and grain isn't really a big deal at all.
If you have already either pen cut your wheel or are cleaning a completed wheel, then do the following. I would recommend not doing this with wheels which have thick black borders though as it creates transparent pixels for some reason:
1. Hit ctrl+J on keyboard or go to layers panel, right click the main logo layer and do a duplicate layer
2. With the duplicate layer active, apply the necessary surface blur
3. Now go to layers panel and make sure the main wheel layer beneath is active
4. Hold down ctrl on keyboard and left click on this main layer thumbnail in layers panel to make a selection
5. Make the duplicate layer that you applied the surface blur to active using layer panel again
6. With any selection tool, right click anywhere on logo and select "Layer via cut"
7. Delete the two layers beneath your new layer as they are no longer required
If the surface blur or noise removal methods don't work good enough, you can simply use the blur tool while zoomed. This usually works best with gradients.