164 140 wheels

Cant remember where I got this info but it was buried in my notes - credit to whoever wrote it - I just recompiled!

I was trying to identify the 5.5 inch wheels under my shed.

The part numbers are stamped on the wheels, even when the sizes aren't. 

P/N 688140-3 are the 15 x 4.5 inch wide, 5 x 114.3 PCD wheels, with 40mm negative offset (40 ET). Early 140 / 164 and P1800s with drum brake rear axles used this PCD.

P/N 684000-3 are the 15 x 5 inch wide, 5 x 108 PCD wheels, with 40mm negative offset (40 ET). These are the steel 140-style wheels you'll see around most often.

5 x 108 is also known as the "HG Holden bolt pattern". 

P/N 684001-1 are the 15 x 5.5 inch wide, 5 x 108 PCD wheels, with 40mm negative offset (40 ET).
Found on 1800s and 164s, '71 to '74.

P/N 1221462 are 1975 164 wheels, which are 15 x 5.5 inch wide, 5 x 108 PCD wheels with 25mm negative offset (25ET). (Anybody with the pdf copy of the 164 Parts Manual dated 1975-03 won't find this part number on Sida 2 of Grupp 6, since it appears to have fallen off the end of the page - but the p/n is in the the Numerical Register. These wheels were are one-year-only special).