Rep. Frank R. Wolf (R-Va.) urged Virginia's highway chief yesterday to delay any change in controversial car pool restrictions on Rte. I-66 inside the Capital Beltway for a year to allow further study.

Wolf, a key proponent of a 1983 congressional measure that eased the I-66 car pool rules, contended that the current regulations should remain in effect until officials have reviewed the impact of the Metro subway system's Orange Line extension to Vienna, scheduled to open in June.

The rail extension, built in the I-66 median, "will significantly alter commuting patterns in this corridor," Wolf said in a letter to Harold C. King, commissioner of the Virginia Department of Highways and Transportation.

"It is important to quantify the number of people switching from I-66 to the rail line," Wolf added. The letter also was signed by three other Virginia Republicans, Sens. John W. Warner and Paul S. Trible Jr. and Rep. Stan Parris.

A highway department spokesman said King would weigh the issue soon. State and federal officials are considering proposals to expand the hours during which I-66 is limited to cars carrying at least three persons.

The restrictions now are imposed from 7 to 9 a.m. and from 4 to 6 p.m. The proposed rules would be in effect from 6:30 to 9 a.m. and from either 3:30 or 4 to 6:30 p.m.