The extreme light at the top makes this really hard (I had the same problem.) I like the idea that wheel is used a support in the picture rather than the subject. A slightly higher shutter speed might have helped on both faces, but that is a judgment call. Good luck. -7
tires aren't wheels (no points lost for that). the hot spot in the middle of the image has almost erased the second child's head. perhaps a fill-flash, and metering on the bright sun light in the middle of the shot would have been better.