Michelin have repeatedly introduced new tyre technology on new millimetric rims
The first radial tyre, the Michelin X was developed on millimetric wheels
In the 1970's Michelin developed the ultra low profile TRX tyres, which were also developed on millimetric wheel rims
Millimetric Radial Tyres
Millimetric radial tyres are only to be fitted to millimetric rims of standard wellbase design. Millimetric tyres should not be fitted to rims with imperial dimensions.
Millimetric Michelin X Tyres
The Michelin X Millimetric Radial Tyres were first marketed as the 'Michelin X' tyre in 1949. To this day the Michelin X is still manufactured to fit 400mm millimetric tyre rims. Michelin still manufacture the Michelin X to fit cars such as Citroens Traction Avante and the early 2CV etc. The Michelin X is still an excellent tyre.