To convert kilometers to miles, you can use the conversion factor that 1 mile is approximately equal to 1.6 kilometers.
To find the number of miles Carlos ran, you can use the formula:
\[ \text{miles} = \frac{\text{kilometers}}{1.6} \]
In this case, Carlos ran 8 kilometers:
\[ \text{miles} = \frac{8}{1.6} = 5 \]
Therefore, the closest measurement of the number of miles Carlos ran is 5 miles.