To find the diameter of a circle when you know its circumference, you can use the formula:
\[ C = \pi \times d \]
where \( C \) is the circumference and \( d \) is the diameter. Rearranging the formula to solve for the diameter gives:
\[ d = \frac{C}{\pi} \]
Given that the circumference \( C \) is approximately 574 meters and using \( \pi \approx 3.14 \):
\[ d = \frac{574}{3.14} \approx 183.4 \]
Thus, the best diameter of the circle, rounded to the nearest tenth, is approximately 183.4 meters.