I have 25lts 1.5hp which works fine and I don't own a beader. Make sure tank is full and valve core is out of the wheel and it normally pops up ok.
As I'm too tight/lazy to buy a beader sometimes use a ratchet strap round outside on a new tyre to get a good seat.
I think tank capacity is more important then CFM for popping tyres on.
One of the best addition to any garage mind as handy for blowing out carbs, brakes calipers, trapped water, crap etc plus painting and stuff