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tire sizes and units

In the US most domestically produced cars are now built with metric sized nuts
and bolts and most measurements are in even metric units. However, wheels are
still measured in inches (13, 14, 15, 16" being the common sized). We then win
d up with tires with the width measured in mm and the rim size in inches. A ti
re size might be for example P205/75 R15 where 205 is the width in mm, 75 is th
e aspect ratio (ht/width) and 15 is the wheel size in inches. Who else uses th
ese mixed measurements? For a while a few performance cars came with metric wh
eel sizes, however, tires were expensive and hard to find. Now they are almost
imposible to get and most owners of these cars have bought new wheels. Are th
ese standard in Europe and Japan?

A related question. Are Shrader valves used in valve stems in the rest of the
world. I know most performance bikes use Presta valves, but I've never seen
them on cars. If you use Shrader valves do they still have English threading i
n the valve stem? (They do in the US!)

If the rest of the world uses metric wheels and valve stems are there any commo
n uses of the use of English units is otherwise metric countries. There are lo
ts of examples of wierd units still in use in this country like point, gauge, e
tc. and I assume there are similar cases in other countries. I'm just curious
about the last vestiges of the English system.