The Indy Racing League is responding to two devastating crashes in October by slowing down its cars in time for the Indianapolis 500 next May, the Indianapolis Star reported Friday.

Engine sizes will be cut from 3.5 liters to 3.0 liters by May, and the league also said aerodynamic changes aimed at slowing the cars further will be announced in January.

"More than anything (it's) for our own peace of mind," said Tony George, Indy Motor Speedway and IRL chief executive officer.

Tony Renna died in a crash during tire testing at the Speedway on Oct. 22 and Kenny Brack suffered serious injuries that he's still recovering from in a crash at Texas Motor Speedway in the IRL's season finale.

With speeds at Indy Motor Speedway above 230 mph, George told the newspaper something needed to be done to get speeds back under 220 mph.

"We were already at the upper end of our (targets)," George said. "We got there about a year quicker than we anticipated, perhaps because of the increased competition."

There was "little doubt'' the change would have occurred even without the Brack and Renna crashes, according to John Griffin, vice president of media relations.

"Those incidents facilitated it among the manufacturers in working with us and realizing we were going to have to make some changes for next year,'' Griffin said.

A report on the IRL's investigation of Renna's crash is "near completion,'' Griffin said.

The IRL has three races on its schedule before the Indy 500 on May 30. Those races -- at Miami on Feb. 29, Phoenix on March 21 and Japan on April 17 -- will be run with the old engine specifications.

"With the accidents that have happened and the potential for cars flying into the audience . . . there's no way we can criticize that this is the right thing to do," Toyota's Lee White told the paper. "We have to control the speeds, and this is the best way."

White said Toyota expects the speeds to fall 15-17 mph at the Speedway.

Information from The Associated Press was used in this report.