i called hyundai's toll free num. the sales rep said that with regards to the warranty, its better to consult their service centers on the type of tryres and rims that you are going to get. she explained that the steering or even the engine might not be suited for your new tires or rims, thus, it may deteriorate faster that it should be. in that case, hyundai may not honor the warranty. i'll do that when i go for my first service (i havent reach 1000 km yet, lol).
so there you have it, i consulted my sales person. he said its ok to change it and it will not void the warranty....however, i tried inquiring via hyundai's toll free number, and they have different answer..