For the second time in three races, the sanctioning Indy Racing League has amended its rulebook to allow for a larger starting field.

Twenty-nine cars are expected at Chicagoland Speedway – the most outside of the 33 for the Indianapolis 500 – to be entered for the PEAK Antifreeze& Motor Oil Indy 300 on Aug. 28 at the 1.5-mile oval. Rule 8.1(E)(5)(f) caps the starting field at 28 cars for races other than Indianapolis, Brazil, Toronto and Mid-Ohio based on pit lane space. The rule also was amended for the Honda Indy 200 at Mid-Ohio presented by Westfield Insurance on Aug. 8 to allow for a 27th entry.

In addition to the 24 full-season entries, expected to join the field at Chicagoland are Davey Hamilton in the No. 21 HP de Ferran Dragon Racing car, Graham Rahal in the No. 02 Quick Trim Newman/Haas Racing car, Sarah Fisher in the No. 67 Dollar General car for Sarah Fisher Racing, Ed Carpenter in the No. 20 Fuzzy's Ultra Premium Vodka car for Panther/Vision Racing, and Jay Howard in the No. 66 Service Central car for Sarah Fisher Racing.