I believe standard equipment is 16cm, for fronts.

you can fit from 13cm to 17cm using adaptors and or spacers.

16cm is the easiest fitment Its been a while since my classic so I maybe wrong

Spacers can be made from MDF, sealing them with some coats of varnish or similar to waterproof first, or use the speaker covers that come with the speakers. Remove the mesh /grilles and use the cover as the spacer


Not sure on the rears, never had a wagon