uses a high quality elastic solid rubber with a hardness of 65 Shore A. Two different versions of the series are available. The -ZDG version uses steel inserts in the smooth rolling tread. The -ZST version in drive quality has a tread which is vulcanised onto a steel-band. Elastic solid rubber tyres have a high load capacity, provide excellent operational comfort and minimise rolling resistances. The black elastic solid rubber tyres also protect the floor.