Thanks for the detailed infos, CBY, Re the tyre size and their influence on the final ratio, the use of 16 inch rims with the ARP4 is not so very dramatical because the corresponding tyres are lower profile ones...225/55/16.
If you compare this tyre diameter with others you get exactly the same all in all tyre diameter as a 4/4 165/80/15 or a Roadster Sport/Plus4Supersort 205/65/15.
Only the regular Plus4 tyre is a bit smaller in diameter when I recall correctly a 195/60/15.
