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_name_88 ( heat_rank INTEGER, overall_rank VARCHAR, time VARCHAR )

### Question ###
I want to know the highest heat rank for overall rank of t63 and time less than 25.47

### Accurate SQL ###

SELECT MAX(heat_rank) FROM table_name_88 WHERE overall_rank = "t63" AND time < 25.47