No sure about it effecting the speedo. Yes, some tyres have ridges built in to the side walls which protect the rim of your alloy meaning you can't kerb it unless you try really hard. It is well worth having them. I think the tyres are 45 profiles.
Fiat Stilo Abarth 3dr. Loden Green, Beige Leather, Sky Window, Cold Climate Pack, 17" Alloys, CD Changer, 260w 8 Speaker Stereo.