Johnny Manziel's fiancee, Bre Tiesi, kept her top ON while flaunting her bikini bod in Miami on  Wednesday ... but if you thought she was gonna be any less hot, you're Wildin' Out.

Tiesi and her gal pal, Jordan Ozuna, hit the beach in Miami today ... and while they didn't bare all on this trip (unlike her last trip) their threads were still barely there enough to get your pulse racing.

We're not sure why Johnny didn't make the trip this time, but we know this ... it must have been really, really, really important.