No, on the Panther the suspension arms, lower hull, suspension torsion bars, retainers for same, drive sprockets, idlers, idler axels and parts therefore including the idler adjustment system, and many other parts are metal. Wheels have bushings in them to ride on the metal axel, which is held in the suspension arm with a set screw. You can easily exchange the bushings for bearings before you build the wheels. Wheels are a tough type of plastic with rubber tyres. Bearings in the wheels are highly recommended to cut down on the little rolling resistance any tank has. However, you must do it on the Panther before you build the wheels, which glue together. KT wheels bolt together, and the wheel discs themselves are again metal.

Have a couple pics. One is a Panther interior. Ignore the TU's, that's a pair of heavy duty competition TU's modified to fit the Panther. Other photo is the interior of the Jagdtiger with an aftermarket suspension system, but it bolts right in to the existing Tamiya suspension rails, and you can see the metal suspension arm bolsters bolted to the metal hull, thru which the metal suspension arms come in to the hull to be joined with the stock torsion bars. The JT, as is the Panther, are fighters, and have many mods to suspension, TU's, etc for the all out competitions I participate in.