Changing Times magazine executives have concluded that the "best way" to keep the 33-year-old consumer magazine alive and growing is to change with the times, and begin accepting advertising.

It is the first major publication to open previously closed pages to advertising since Readers Digest made the switch in 1955, publisher Nicholas Niles said yesterday. Initial ads will be included in the issue of next March.

The monthly magazine, with 1.4 million subscribers, is published here by Kiplinger Washington Editors Inc., which also produces the Kiplinger Washington Letter and four other newsletters.

At a news conference in New York yesterday, where Kiplinger opened an advertising sales office, Company President and Editor-in-Chief Austin Kiplinger said the possibility of accepting advertising had been examined over a long period, since it was surviving on a subscription base alone.

In a time of rapidly escalating costs, we were looking at the prospect of regular and steep increases in our subscription if the magazine were going to carry its own weight," he said.

Niles, who became publisher in June, also announced that Clifford Tallman Jr. will be advertising director of Changing Times. Tallman formerly was associate advertising director of the New York Times Co.'s Us magazine.