you can use row data bound event of grid view to re-size column width.
use following code :
protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
(
if (e.Row.RowType == DataControlRowType.Header)
{
e.Row.Cells[1].Width = 100;
e.Row.Cells[2].Width = 100;
}
if (e.Row.RowType == DataControlRowType.DataRow)
{
e.Row.Cells[1].Width = 100;
e.Row.Cells[2].Width = 100;
}
}