Shares of the Carrollton, Texas-based company fell sharply.
Earlier in the day, the company posted first-quarter earnings of 30 cents a share, ahead of analysts' expectations of 20 cents.
In a filing with the U.S. Securities and Exchange Commission, the company said shareholder Capital Southwest Venture Corp., a unit of Capital Southwest Corp.
The sale of 5.2 million shares will reduce Capital's stake to about 15% or 4.1 million shares. Other executives and board members also plan to sell a combined 2.8 million shares of their holding, Heelys said in the filing.
Underwriters are given an option to purchase another 1.2 million shares to cover over-allotments, the company added.