A compressor may be necessary for tubeless conversions, using tires (and rims) not intended for tubeless use. Personally I will never use them as their success is basically a crap shoot.
I will only use rims and tires that have been designed for tubeless use , i.e. UST, TLR, 2Bliss, TNT etc. and UST or Stan's BST rims. There are other tubeless rim types that I have not tried. I have never had nor used a compressor to mount and seat tubeless tires. All that is needed is a floor pump and the tires are easy to seat.
Mtbr's 2016 Winter Biking GearReviews and Roundups
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