CD & DVD makeing a dvd smaller

[SUPERTOM]

hi all me m8 got a problem most of my dvds are to big to copy thay are over 4.7 gb. i use smartriper but when i take out a vob file nero will not burn it.so is there a way too make them smaller so thay will fit on me 4.7. i only use nero 55.8.2. if there is a way to use nero to make them smaller i will need a guide to help me do this can someone help me ...............