It's a fact.
3 seconds sound clip from the My Cousin Vinny movie soundboard.
You can hear this line at 01:46:19 in the Blu-ray version of the movie.
Quote context
[...]
- How could you be so sure? (2)
- Can we clarify to the court whether the witness is stating opinion or fact?
- Would you like me to explain?
- The car that made these two equal-length tire marks had positraction.
- You can't make those marks without positraction, which was not available on the '64 Buick Skylark.
[...]