Corsa-B.uk - Vauxhall, Opel and Holden Corsa B Owners Club

if you are interested in finding out how much your speedo is out when you have fitted your new alloys,just type in you original tyre sizes then the tyre sizes that you want to use,it will calculate the % that your speedo will be out,

http://www.maita.net/garage/tirecalc.html

sorry chaps this link dont work.