Schizo' tyre sizing

[wolfracesonic]

Anybody have any idea why we have ended up with tyre sizes utilizing both the metric and imperial system i.e 265mm wide, 18'' diameter and how long will it be before the E.U declares the 18'' should be re-classified as 457mm?

[littleredrooster]

...and while you're at it, explain why bike tyres are sized in tens, not fives - 130, 160, 190 etc.

[Matt UK]

...and how come we all know MPG, yet understand our fuel in litres?

[shoehorn]

Probably done at the time when radials were introduced to make it easier to differentiate between those and cross plies.