I bought the steel rims from renault 45 Euros each and the rires from dackonline.se , 38 Euros Each. These are not exacltly the rekommended sizes but close. Fronts are 145/70-13 and rear 155/70-13 to keep some difference between front/rear.
The reason for the tire sizes on the twizy is safety, the car should always understeer. The german twizy community have adopted 145/70-13 in front for a more neutral handling twizy. That with original size tires in the rear. So I think I will be fine with these dimensions.