The Friedmans on pressures against change; Tyranny of the Status Quo, by Milton and Rose Friedman. San Diego: Harcourt Brace Jovanovich Inc. 182 pp. $10.95.

The Friedmans describe the ''tyranny of the status quo'' as a political inertia characterized by ''an iron triangle of beneficiaries, politicians, and bureaucrats.'' It amounts to a democratic version of European conservatism, in which special interests strive to maintain positions of privilege.

This book is somewhat eclectic, though predominantly pro-free-market, as one would expect of the Friedmans. Economically, the explanation of inflation and the fascination with price indices is vintage monetarism. The idea of using fiscal policy to compensate for the business cycle is Keynesian. The frequent mention of the incentives to which individuals respond introduces a pronounced supply-side flavor.

Politically, the William Simon-like verbal assault against big government is conservative. The recommendation of legalizing underground narcotics is distinctly libertarian. Occasional lapses into interventionistic positions and free market rhetoric with loopholes are obvious concessions to liberals.

In short, this is a minor book which is little more than a postscript to the Friedmans' best seller, ''Free to Choose.'' Still, designed for popular audiences as it is, ''Tyranny of the Status Quo'' will find its niche among those who are chafing under the burden of government. For many, though, the summary given in the last chapter (three-plus pages) will suffice. The unusually lucid discussion of the ''balance of trade'' problem (pp. 124-129) is also recommended.