T.I.'s Sister Precious Harris Dead At 66

T.I.'s older sister, Precious Harris, has died ... according to her daughter.

Precious died Friday, just over a week after getting in a super serious car accident in Atlanta. Her daughter shared a tribute to her mom, saying ... "From my bestfriend on earth to My beautiful angel in heaven."

She added ... "I love you so much. I’m so heartbroken but the way you looked so @ peace this past week has confirmed that you are resting... no more asthma attacks... damn but baby I am going to miss you."

Sources close to the family tell us Precious has been on life support since the accident and was never responsive.

We're told Tip and Tiny are devastated. T.I. was incredibly close to his sister, and so was Tiny. Tip shared a message, too, saying ... "We Love You Dearly Baby Girl...."

As we told you, T.I. and Tiny shut down production of 'Friends & Family Hustle' last week, after learning Precious was involved in a wreck earlier that morning.

It's unclear what led to the car crash, but here's what we know ... sources say Precious hit a pole, which triggered an asthma attack. Precious -- who often appeared on the show -- was taken to a hospital and placed in ICU.

For Precious' 66th birthday bash last May, Tiny gave her a shout-out and said, "I hope you know how much u mean to me. Always been my road dawg. Love u much! Hope you enjoyed your day!!"