I'm sure it says that only because its not a factory spec but if you look at the biggest wheel available and match it up to the 245s, you will see the 245 be slightly smaller. I use Tacoma Worlds tire calculator to see the side by side and overlayed comparisons.
I like the look, so If I were to hypothetically lift a vehicle, I would want to keep the angled look. Especially since I dislike/despise leveled/squatting trucks.