Make sure you always give full input with your joystick during the turns so the curve is as tight as possible.
For the first three of the lower reds you can line up Mario like that to get a good turn.
[1]
For the last one of the lower reds you can line up Mario like that to get a good turn. This allows you to turn really early, as in the video below.
[2]
![[1]](https://i.imgur.com/Sw3nwo8.png){kind=link}
![[2]](https://i.imgur.com/3cFhefJ.png){kind=link}