Expiration Time - 72 hours
72- hour permits are vehicle specific. Permits are valid for 72 hours/3 days. Illinois currently allows the purchase of 3 IRP trip permits per vehicle before apportioned license (IRP) license must be purchased. No more than 3 trip permits may be issued per vehicle in any 12-month period.
In lieu of obtaining an IFTA license, you may satisfy your Motor Fuel Use Tax obligation by purchasing Single-Trip Permits for each jurisdiction in which you are traveling. A Single Trip Permit for Illinois allows a motor carrier who operates commercial motor vehicles to travel into or through Illinois for a 96-hour period without being registered in a motor fuel use tax program. If you are a carrier in need of a Single Trip Permit, please contact a Single Trip Permit provider. Single Trip Permits for Illinois must be purchased before entering Illinois.
Source of information: https://www2.illinois.gov/rev/research/taxinformation/motorfuel/Pages/motorfuelpermits.aspx