Extreme rhymes with:
downstream, stream, upstream, downstream, stream, upstream, avrim, bream, cream, creme, downstream, dream, greim, grieme, priem, ream, reim, rheem, riehm, scream, stream, supreme, upstream
Extreme sounds like:
eastern, eckstrom, ecuadoran, ecuadorean, ecuadorian, ekaterina, ekstrom, equestrian, estrin, excedrin, eyestrain