Quote - You might go with 200 dpi . Just mutiply it out.

I agree. 200-240 pixewls per inch (ppi) usually retains all the detail you need. You might even get away with 150ppi and no obvious pixellation if the image doesn't have too many straight lines (like wheel spokes etc.). Do one at each setting (150, 200, 240, 300) and see which one looks best viewed at A3 on your monitor. If you use Photoshop, you can click "View-view print size" and get a reasonably accurate same size view of your image.