I've been mulling over wheel sizes and gearbox and diff ratios trying to decide what'll be best for my Cabrio rebuild and engine swap. My original build used Compomotive CX wheels and these are stamped "6.00Jx15x23-38mm NEG".
Although I doubt very much I'll re-use the wheels I'm trying to decipher the size. The 6, J and 15 are easy enough to figure out (6" rims, J bead profile and 15" wheel diameter) but the 23-38mm NEG part is leaving me a little stumped.
I wondered if it means a range of negative offset values depending on the size of any spacer used. However, if I measure the offset then it seems to me they're actually a 23mm positive offset i.e. the mating surface is 23mm outboard of the wheel centreline. But adding a spacer will reduce the offset, won't it? So maybe it's 23mm positive to 38mm negative, and the max negative offset is achieved with a 61mm spacer? I've never used wheel spacers but 61mm seems helluva big (and a strange number, although it does convert to 2.40").
Anyone got any ideas as to how "23-38mm NEG" is supposed to be interpreted? My google-fu has deserted me today...
16 Oct 2011, 1:56pm