Which city's metro system runs entirely on rubber tires?

The metro system that runs entirely on rubber tires is Montreal’s Metro.

The Montreal Metro, serving Montreal, Quebec, uses rubber-tired trains rather than relying on conventional steel wheels for normal running. Rubber tires run on concrete guideways, while guide bars and backup steel wheels help control and support the train. This arrangement gives the trains strong acceleration, smooth operation, and the ability to handle relatively steep grades.

The system opened in 1966 after Montreal planners and French engineering advisers selected rubber-tire technology. The choice reflected French influence, especially from the Paris Métro, and suited a network built largely through rock beneath the city. Montreal’s metro is also unusual because its entire network is underground.

“Entirely on rubber tires” does not mean the trains contain no steel wheels. Backup steel wheels remain part of the bogies and are used in emergencies and at certain track interfaces. Mexico City, Lille, and Paris also operate rubber-tired metro lines, but Montreal is the canonical city-wide answer for this question.