My car's wheels diameter is 380mm: about 15", it was available with 400mm rims too, about 16". Never heard of 390mm rims though. Pipe work is in inch, wood and sheet metal screws diameter are in inch but converted in metric leading to stupid measurements like 3.2mm but length are in metric. Worst I've seen is US size reamers converted to mm. So when you know you have to ream lets say bushings to 11/32 you have to convert to know which one you need to order because those dumb asses don't put both measurements, evidently that leads to errors... Funny thing is when Simca got hold of Ford SAF they still used inch size bolts on the flathead but with metric heads so shops around the country could work easily on their engines, but how many thread got fucked because the mechanic tried to insert a metric bolt into an imperial thread?
Good luck on the carb I had one a while back that had sat still for 30 years. I ended up finding a great carburetor shop in Phoenix Az. Now it works perfect..... As for the tools living in Denmark for many years, I found buying tools on the internet was my best tool supply....
Inches/.039370 = mm. mm x .039370= inches. All you need is a calculator or, if you're really smart, paper and writin' stick.
Wondering why memorize 6 numbers if it works with 3? 25.4 seems way easier to me, and is faster to punch in the calculator too...
and 25.4 is "exact" so it is accurate to beyond 30 decimal places, not that it matters when calculating to 3 or 4. looks like there are places online using 25.5 as the conversion. http://crystal-emporium.com/metric_chart.html
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