Why was Zac Efron not on there tour?

Answer 1

because he doesn't sing in HSM a lad called drew does zac only lip sings

^user 1's answer

i thought it was because he was doing the movie hairspray

^user 2's answer

His voice is used for some of the singing in HSM1. But, according to the studio, the songs were written for a tenor before Efron was cast (he's more of a baritone). So Drew Seeley overdubbed Efron's voice where necessary. Efron didn't go on the live tour because he was preparing the Hairspray and he was a little sick of hearing the HSM songs.