215 ILCS 5/143.13a

Any policy of private passenger automobile insurance must provide the same limits of bodily injury liability, property damage liability, uninsured and underinsured motorist bodily injury, and medical payments coverage to all persons insured under that policy, whether or not an insured person is a named insured or permissive user under the policy. If the policy insures more than one private passenger automobile, the limits available to the permissive user shall be the limits associated with the vehicle used by the permissive user when the loss occurs.