Denne testgruppe omfatter alle bremsetromler, hvor tromlens indvendige diameter ikke varierer mere end 10 % (i forhold til den laveste værdi) og mere end 40 mm hvad angår bremsebakkens bredde.
This test group includes all brake drums that do not vary by more than 10 per cent (referring to the smallest value) in terms of the inside diameter of the drum and by more than 40 mm as regards the shoe width of the drum brake.