1:35 Sagged Wheels Sd. Kfz. 7

The front wheels of the eight-ton tractor

The Sd. Kfz. 7 was a German half-tracked artillery tractor made by Krauss-Maffei, deployed from the end of the 1930s to the last weeks of the war. It towed heavy anti-aircraft guns and heavy howitzers and carried their crews. At the front it had a steered axle on pneumatic tires, and at the rear a tracked running gear with interleaved road wheels.

What a sagged wheel is good for

A solid rubber tire on a model pretends to be a perfect circle, whereas a real wheel settles under the weight of the machine, the bottom flattens and the sidewall bulges slightly. That single detail decides whether a vehicle stands on its base or floats above it. On a tractor with an empty bed and a gun hitched behind it, the load on the front axle is clearly visible, so the difference shows even in a photograph.

Replacement procedure

Cut the original wheel off with a saw on the axis of the hub, level the surface on sandpaper laid on glass and fit the new part so that the flattened section bears on the base across its full width. Make sure that both wheels have the tread turned the same way and the same plane of contact, as an asymmetrical stance stands out more than the original round wheel.

Painting

Rubber is not black: it looks best as a dark gray base brightened on the crown and complemented by dust in the grooves of the tread. The sidewall of a tire tends to be dusted evenly, whereas the tread stays noticeably darker and glossier, because it rubs against the surface of the road. The rim is painted in the same shade as the vehicle, and only once it is dry is the rubber part fitted, otherwise the transition between the two colors is hard to keep clean.