its can be dangerous mixing rim sizes,although it isn't illegal.it may pose a problem if you need to fit the spare though,as for the leaky roof,you have a few options available silicone or a water repelant sealer available from most motor factors such as halfords.don't seal from outside if you can help it.remove head lining and seal joints up from insde,.it will look better.
tranny granny, November 2011
