Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_15416002_1 (r_miles_ VARCHAR, chi VARCHAR)

### Question ###
What are the miles when the Carvill Hurricane Index (CHI) is equal to 9.9?

### Accurate SQL ###

SELECT r_miles_ FROM table_15416002_1 WHERE chi = "9.9"