Hello, Here in the USA the SL550's do not come with any spare tire, jack, tools or air pump. I understand in the UK that you can get this as an option. I know the collapsable spare is made by Vredestein and can only be ordered through a Mercedes dealer. Additionally the well under the trunk...
I couldn't work out how a tyre could 'fold' as it were to save space in the SL...Until I found these vids on Youtube-Never seen anything like it.
Inflating: YouTube - Vredestein Space Master
Deflating: YouTube - Vredestein Space Master
Obviously not on a Merc rim, but the same tyre.