Kyle Busch led 62 of the 63-lap Lilly Diabetes 250 last year. The changes were determined after several teams tested last fall.

NASCAR has modified the splitter, front bumper structure, spoiler and aero ducts in an effort to put more drag on the front of the car. Teams will also incorporate both a 7/8 inch restrictor plate along with a NASCAR-supplied four-hole tapered spacer with a one-inch thickness. The initial change is expected to knock off 200 horsepower from the Xfinity cars. The final restrictor plate hole size will be determined following Happy Hour.

NASCAR has also scheduled a make-up tire test for Goodyear at Michigan International Speedway on July 10-11.

The original test planned for April was rained out. The four teams scheduled to appear include Richard Childress Racing, JTG Daugherty, Stewart-Haas Racing and Joe Gibbs Racing. The test marks the fifth designated tire test of the season.

The Monster Energy Cup Series is scheduled to race the FireKeepers Casino 400 on June 18. The April test would have enabled Goodyear to develop a new tire combination prior to the race. With the rescheduled test, the tire company could possibly turn something around in time for the August races.

NASCAR makes rules bulletin update

Wednesday’s announcement in NASCAR’s bulletin also addressed 20.4.4.1 Front Bumper Structure — which makes splitter support bars optional at Martinsville Speedway — and

Vehicle and Driver Safety Specifications - 20.2.3.2.2 Seat Installation, to include added height dimensions.