Driving around on Mars is tough. I’ve been watching the wheel wear since I noticed what I thought was unusual wear back in November 2013. I know NASA is watching also, they are taking regular images of the wheels and possibly watching the substrate under the rover too (I think I read that at some point but I could be wrong too).
So just to keep you updated, this particular image was taken a couple of days ago on 17 July (Sol 691) and you can plainly see the wear. Hard to say if things are getting worse or not, I’m going with not. The treads look good and the in-between parts would be less of a concern if the inner and outer parts of the wheel were tied into the treads somehow and they could be. So, I’ll stay optimistic, but I’m still surprised at the extent of the wear.