Thanks for the various feedbacks and suggestions. For my part...ive only gotten as far as dismantling the tyres fromm the wheels. The rim shop at USJ suggested to use the windscreen glue to seal the wheels, but I wasn't sure whether this would tahan or not. The slow puncture is quite irritating if it happens so I was looking for a more durable solution. Anyway, I guess if even normal silicone would work (as suggested by anakin) then maybe my concerns were not warranted. Actually these rims are no longer mounted on my e30 so i have time to spare. Im using the ac types ones for now since they are soooo much easier to clean...I'll be back next wknd so will first call up the first suggested rim specialist to see if he can help.