Can of worms......

Just going by the number of 5mm wheels for sale compared to 3mm wheels you have to think more cars had 3mm wheels. HZ didn't sell all that many cars and HX lasted only one year. Just estimating that maybe 3mm wheels were available a bit earlier. Plus as van be seen they were a copy of a US wheel anyway so perhaps there were 3mm and 5mm being produced at the same time until ADR rules stopped 5mm production.