right, i had 205 50 15s on and speedo was slightly out. Now i got correct size 195 55 15s and it don't seem to have made any difference.. What else cud it be.cud it be the speedo itself?

http://www.fiatboo.co.uk/tyres.htm

Speedo will never be that accurate.  Check on original wheel and tyre size for your model against your latest size

i got standard size bk on from 205 50 15 bk to 195 50 15. i suppose as u said wimmy speedo will neva be accurate. seems ok tho tiny bit beta.