Here is the link that thedoor mentioned for the trucks and wheels, they are the best you can get.
speedsailshop.comI have the same set up. The wheels are a bigger diameter than most and it really helps in the areas where the sand gets soft. One of the reasons for the wider back trucks is so the back wheels loose traction in a turn first (oversteer) and this is safer than the front wheels sliding. The big con of the wider back trucks is you can't kick it like a skateboard, also you have to step off wide when bailing out or the back wheel gets your calf. If you are after speed and want to ride fast, then make the back wider. I keep the speeds lower than I can run and I am all about doing transitions and I sometimes wish for narrower back trucks. The black plastic on the trucks doesn't help anything in fact it promotes corrosion, I took them off my set up with my favorite tool the angle grinder. I only use the front mast base hole. Although I have tried sailing it backwards so I could kick it in light air, you can see the hole near the back trucks. Have fun and be safe!