Simon, same ans. I gave you on BF this am...
For those that are interested or curious in doing wheel/tire size change and its pot. effect on , here's a good site that you jes'plug in old tire size, new tire size and you get your "answer":
http://www.powerdog.com/tiresize.cgi
For exp., I listed the wheel&tar setup on daFridge, aka the Honda CRappyVehicle: stock and a plus 1ish set up I went to a year ago:
SpecificationSidewallRadiusDiameterCircumferenceRe volutionsSpeedometerOdometerDifference205/70-155.6"13.1"26.3"82.6"767/mi60MPH10000miN/A225/60-165.3"13.3"26.6"83.7"757/mi59MPH9876mi1.3%
BR, Ol'UncleMotor