If that Tyco road-racing set or model train you've always wanted wasn't under your Christmas tree this year, fret not, an after-Christmas sale is coming that will let you buy the whole Tyco Toys company for $7 a share.

While most toy makers were spending Christmas Eve in the recovery room, Tyco Toys Inc. on Tuesday sent its lawyers to the Securities and Exchange Commission to register its plan to sell stock to the public.

Tyco now is owned by a New York investment company named Savoy Industries Inc., which bought the business from Sara Lee Corp. in 1981 for about $18.6 million. Savoy is offering investors the chance to buy at least seven-eighths of Tyco for $13.5 million, and will sell its entire interest in the company if the stock offering is sold out.

The stock sale seeks to raise about $22.4 million, of which a maximum of $16.3 million will go to buy out Savoy; the rest will be used to finance future Tyco operations.

Tyco has made model railroad equipment since 1926, and its sales of $12.7 million worth of train sets last year made the company one of the biggest names in little trains.

Tyco is also the nation's largest maker of HO-scale electric road-race sets, selling $30 million worth last year when the electric car business recovered from an attack by electronic games.

The company tried to merge its two best-known ventures by creating electric trucking sets in 1981, but sales of Tyco US-1 truck sets peaked in 1982, and it's been downhill ever since.

The newest growth toy for Tyco is called "Super Blocks" and is meant to compete with, and connect to, imported Lego construction sets.

Introduced just two years ago, Super Blocks produced $15.6 million in sales in the first 10 months of 1985.

It also produced lawsuits filed by Lego in the United States, Canada and Hong Kong accusing Tyco of copyright infringement and unfair competition, the stock offering statement notes.