just installed new wheel nut locks and noticed they are much heavier than normal nut. does the wheel require balancing because of this?

Wheels are normally balanced off the car so the weight of the nuts/studs aren't taken into consideration. The closer to the centre any unbalance is, the less effect it will have so it's unlikely that a few extra grams of nut will make a noticeable difference. Of course, if you notice any vibration it needs looking at, but I doubt you will.

thanks!