Depends on the type of track the M50 comes with. I'm not sure and don't have that kit in front of me, but if the cleats on the track pads are a thin wave line (kind of makes a bell shaped curve when looked at from the front), then the track is all steel front and rubber inner surface.
If the outer cleat is a thicker line, then it is all rubber.
Cookie Sewell's review is for the newer kit of the M51, but the Israelis favored the all steel faced T80 track. Desert conditions can wear out rubber really quickly.
http://www.missing-lynx.com/reviews/modern/dragon3539reviewcs_1.html