We use the metric system in Australia but we also use imperial. The switch happened back in the early 70s.
I use both daily. For instance, I prefer foot pounds to Newton meters.
And our tire sizes are still imperial.
FYI: Search
"Metric tires Ferrari Testarossa" on Google and you may be surprised (The first Testarossa came fitted with millimetric wheels).
I'm also a Measurement Geek:
http://forums.pelicanparts.com/off-topic-discussions/641397-heavy-pink-american-d.html