T.I. & Wife Tiny -- We're NOT Splitting Up

T.I. and his wife Tiny are NOT calling it quits after 3 years of marriage ... despite reports to the contrary ... the rapper tells TMZ.

Rumors circulated like crazy after T.I. was a no-show at the Grammys and he and Tiny partied separately afterward.

T.I. tells us yeah, there was a big argument, but it was over something pretty stupid. Tiny wanted to walk the Grammy red carpet and watch the show but T.I. wanted none of it. He says they angrily challenged each other on who would end up having more fun that night.