I know...I know...These are not super soft microfiber or some other unicorn hide, but these are needed. At least, I need them. As long as you keep an eye on the top of the brush, there is a rubber tip protector on it, these brushes last forever. I use them on all of my wheels and haven't noticed a problem with scratching. They may mar the inside of the wheel, but I'm not usually analyzing this too closely. I'm not exactly sure how long I've had my original 2 brushes, but it's been 5+ years.
I use these on:
The area behind the caliper where the Incredibrush doesn't fit on the wheel barrel.
Occasionally in the engine bay
I have both the Large and Small in my wheel bucket. My suggestion is that you have them both as well.