The Securities and Exchange Commission is investigating Firestone Rubber Co. to determine whether firms should be required to report to stockholders actions that might involve civil penalties, Time Magazzne said yesterday.

The Washington Post learned that the SEC also has asked questions about the circumstances surrounding the proposed merger of Firestone with Borg-Warner.

The merger discussions with Borg-Warner surfaced at the height of Firestone's massive recall of the 500 series radial tire. The merger was called off within the past month.

Knowledge of firestone's troubles with the 500 apparently was not communicated to shareholders.

Memos circulated within the Firestone company and previously published in The Washington Post indicated its former president Mario De Federico, knew of the problems with the 500 tire as early as 1973. Time reported yesterday that Firestone's director of development, Thomas Robertson, warned in a 1973 memo that the company was making an inferior tire.

Time said Firestone acknowledged the investigation inot stockholders disclosures, saying it was designed to see if the company "disclosed in a timely manner" information about the tires. Time also said Firestone spokesman werw confident the SEC would rule in its favor.

Last year, Firestone said it would stop producing the 500 and would recall all the 500s on the road, after road accidents and other problems caused by allegedly faulty tires were reported.