The cutting torch will most likely only succeed in destroying the finish of your alloy rims as the melting point of the alloy is lower than that of the nuts. Best thing in my experience back in my tire changing days (Canadian Tire taught me a few things) is to peel the shell off the nut, clean the rust off the sides of the nuts (will usually flake off with some light chisel work) to square them up, then grab a socket next size down, hammer it on, then use a breaker bar. After, take the socket to a vise, and hammer the nut out using a punch through the drive hole. Best to work with 6 sided 1/2" impact sockets for this kind of job.
Good luck