To the best of our knowledge a driving record in Illinois is not cleaned off when you reach the age of 18.

The IL driver's manual states that the Secretary of State (SOS) keeps records of the traffic violations and accidents you accumulate while a resident of Illinois. If you are convicted of a traffic violation while driving in another state, the offense will be included on your record as though it happened in Illinois.

Even if you are not a resident of Illinois but you are convicted of an immediate action traffic violation in Illinois, a record will be established for you in Illinois and the traffic violation also will be forwarded to your home state.

There is no mention by the SOS or in the IL driver's manual of the driving record being cleaned off when a driver turns 18.You can check however with the SOS to find out for certain if a minor's driving history is wiped clean once they turn eighteen year old.