Don't know the availability of this tyre or price in the USA but its about the same OD as the 135/70r18 tyre.
Vredestein 175/55-18 as fitted as spare to MB SL, Biturbo, MB E 55 AMG, MB CLS 55 AMG.
http://www.vredestein.co.uk/Banden_B...&BandtypeID=25