the dealer says the amg sports pack rims must have airmatic on the car (only an issue if one buys then as an accessory). is that the case?
is the ride quality clearly different than 20"? ( which come stock on 350s in Australia and I thought ride great on steel springs ).
thanks

I have the 21s on airmatic and my wife loves the ride......can't see it could be "bad" on steel springs. Will be just a bit firmer than 20s, but I bet most would not tell the difference.

Well I switch from 20's to 21's (GL450) I can tell the difference, ride is a lot better, firm, clearly can tell the difference... the bad is tire replacement cost... about $450 per tire ouch !

Wally, that comparison is not really valid.

Jellies query is about the ML which has 265/45R20 or 265/40R21
These tyres have 119mm and 105mm rubber height from tread to tyre bead.

You were citing the GL which has 275/50R20 or 295/40R21
These tyres have 138mm and 118mm rubber height from tread to tyre bead.

So the 21" on the GL has the same rubber height as the 20" on the ML.
It also has a much wider tyre so it should have better traction.

Of course when you fiddle with aftermarket rims, you may also fiddle with the tyre selection too, which could leave this debate wide open.