Johnny Manziel Tackles Tough Questions ... About Justin Bieber's Dreadlocks

Johnny Manziel's not even talking about his NFL future anymore -- and instead he's moved on to more heady topics ... about his pal Justin Bieber.

Yes, Johnny Football happily talked hair Monday afternoon in Bev Hills -- 'cause like everyone else on the planet ... he's got an opinion about Justin's new dreadlocks. Remember, Johnny and the Biebs kicked it at 1 OAK over the weekend.

Check it out ... this video proves Manziel's in full Hollywood mode. He's even walking out of the super fancy Saint Laurent store on Rodeo Drive.

Hear that, L.A. Rams? He's all in.