I have a security bolt in the rear wheel, mainly because the wheel rim is a stainless one and even though the rim had serrations where the tyre mounted, they appeared to be quite smooth and was conerned with tire creep under acceleration. I didn't bother with the front.
Position of the security bolt in relation to the tube's valve is shown in Know thy beast. (sorry I don't have my copy with me).
Note : when a security bolt is used, two extra bolts are also used to mount lead weights so as to balance out the security bolt. this is also in Know thy beast.