The reason is because the actor Charlie Hunnam didnt like how boots felt and he was more comfortable in the white sneakers

<p>Kurt Sutter and Charlie Hunnam did a tremendous amount of research for the role, <span style="font-weight:normal;">hanging around various outlaw MC's, as well as RC's & Oakland bikers in general, conducting personal interviews with members. Hunnam</span> said there was one specific kid he met in this club who was exactly who he was hired to play; he was the son of a man in the MC, he'd grown up in the club, every one of his birthday parites was thrown in the MC clubhouse.  </p><p>Hunnam stated that he wore the exact shoes he wore, as well as the type of jeans he wore, and went on to say that this kid was an amazing guy and had a powerful impact on him, but was shot dead before SOA started production, which is one of the reasons Hunnam wore the bullet necklace, 'I wear if for him -to remember the flavor he taught me.' </p><p><span style="font-weight:normal;">Kurt Sutter mentioned that they noticed a Hip-Hop influence among some of the prospects and younger members, many wearing very clean white tennis shoes. He also mentioned, that another aspect of the subculture among the older, aging members, who have been involved for a number of years, was that they sometimes valued comfort over appearance when riding, trading in their choppers in some cases for more comfortable, touring type bikes. M</span><span style="font-weight:normal;">any began riding with tennis shoes simply because it was more comfortable, and they felt that they didn't have anything to prove to anyone. They may change into boots once they get where they're going, for the 'look.'</span> </p><p><span style="font-weight:normal;">This is from a few different interviews/articles and other things I've read, so I'm quoting and paraphrasing from memory. I enjoy the show, but I'm by no means a superfan; however, I'm always interested in interesting details, background stories and history, wasting time reading and picking up crazy but ultimately useless ephemera, so I can't recall when or what sources I gleaned this stuff from (it was all online/locatable), but those with more comprehensive knowledge may be able to correct me and/or identify sources.</span> </p>