William Harvey du Cros (19 June 1846 – 21 December 1918) was a Dublin-born financier, the founder of the pneumatic tire industry based on the discovery of John Boyd Dunlop, a Scots-born Belfast veterinary surgeon. Just 65 inches tall and a noted athlete in his youth, he remained an enthusiastic cyclist and a skilful boxer into his middle age. He was briefly a Conservative Party politician of England.
Son of Edouard Pierre du Cros who was of French Huguenot descent and Maria Molloy he was educated at The King's Hospital, Dublin. He married Annie Jane Roy in 1866. Advised when aged 30 to take up sport for the sake of his health, he became Ireland's: boxing champion at two weights; fencing champion; founder and captain of a team which won the Irish Rugby championship and, having six sons by the time he reached his late-twenties, he formed them into a successful team of racing cyclists, The Invincibles, on solid tyred penny farthing bicycles. He was president of the Irish Cyclists' Association.
Later in life he was described by the Revue Franco-Anglaise as dapper, below middle height and of robust build with an expressive face and a high forehead. Quite modest and of a retiring disposition his pleasant open face invited friendship and confidence. He seemed to have a ready willingness to listen.
Two of his sons were beaten in a cycle race by a little-fancied competitor using John Boyd Dunlop's rudimentary pneumatic tyres. Seeing an opportunity du Cros, now well known in Irish business circles and president of the Irish Cyclist's Association, managed to be invited by his friends J M Gillies and Dublin cycle agent, William Bowden, Bowden being the new owner of the rights to Dunlop's patents, to form a public listed company and exploit the patents. Bowden persuaded Dunlop to join them and promote the new company. Du Cros successfully floated the company's shares keeping all arrangements under his own control.
In 1896 he sold that company to a group of people including Ernest T Hooley for 3 million pounds. The business was then refloated to the public as Dunlop Pneumatic Tyre Company in May 1896. That business produced its first car tyre in 1900, considerably after Michelin, and began to diversify into aircraft tyres and golf balls.