The Gazelle I-IIIC was originally fitted with a 560-15 crossply tyre (although some years a 500-15 was shown in the catalogue, with a 560-15 option). A radial replacement size for this would be 155R15.
From 1963 the Gazelle V-VI had a 13-inch wheel with a 600-13 crossply was fitted. A 165SR13 would be a suitable radial replacement for this.
The completely remodelled Gazelle VII of 1967 was fitted with a 560-13 crossply tyre, that can also be replaced with a 165SR13 radial tyre.
The Gazelle was a badge-engineered version of the Humber Minx, Rootes now being in charge. Constantly upgraded during its life, it sold well in the family car segment.