What size screws will I need for the sideskirts of a 99 Vauxhall Vectra?

I'm fitting new sideskirts to a face-lift Vauxhall Vectra B. The plastic push-pins used to secure the skirt to the underside of the car have to be drilled out, meaning they cannot be reused. These pins can no longer be bought, meaning a screw will have to be used.





Would anybody know what size screw I should use? I presume a self-tapping of some size, but any advice would be appreciated.|||Just use a bolt and nut combination that will fit in the skirt holes. That or, zip ties are really effective. These skirts are flappy thin plastic so zip ties do the trick. Then everytime you need to take them offf to work you just cut em, and put new ties back on after you're done.