I find the whole tone of the discussion here ironic mostly because the ETRTO system is mostly useful for those who are buying a tire to mount to an obsolete rim.

I must admit that I'm an engineer who has worked in industries in the USA that are primarily imperial (civil engineering, mechanical/HVAC design) and in the USA and Europe in a more metric environment. Hell, I nearly became an Architect (1:48 and 1:96 scale, anyone? 1/4" = 1'-0", 1/8" = 1''-0")! 27 cubic feet in a cubic yard, which is the common unit of excavation. 12000 British thermal units per hour in a ton of air conditioning capacity. We even have Rankine! It's like if Fahrenheit liked really cold weather!

The thing is, these units are useful in the places where they're used (with the possible exception of Rankine... ). I thought I was well acquainted with metric units, but never really had a feel for them. Now I live in a place where my keyboard has the keys to easily indicate the Ångström and the µm, units I've used frequently in my work in the past and present. But, you buy a 28 "thumb" tire, which of course is the 700c or 29" size other places. There's even 'en mil', which people generally translate as 'a mile', and you'd better have very good energy if you think you're going to walk those ten kilometers in 10 minutes. And you won't be able to take a shower if you don't understand that the plumbing threading is also in nominal imperial sizes, but the pipes are in nominal metric sizes.

I think that some clarity is always good, and recommend some standardization. But, alternate standardization isn't necessarily inferior to that which you (or I) are accustomed to.

Standards in measuring things are, I think, good. Standards in judging another for his system are, well...