Huge (Huge ) gurgled happily, sounding much
like they were saying:

Tyre sizes must drive the metrication fascists bonkers; three numbers,
one metric, one imperial and one dimensionless

Not exactly "dimensionless".

So, what are it's dimensions? Acre-feet? Lightyear-barns? Barrels per
kiloparsec? It's a ratio, and therefore dimensionless.

It's one of those "it is and it isn't" numbers, I reckons. No, on it's
own, it is dimensionless, but taken as a whole at least it's easy to turn
into an absolute dimension - unlike the load rating number...