On the 747 - 5-8kts round a 90 degree turn, 10-15kts or below in a terminal area, 20 kts + in a long straight line though Boeing are happy up to 30.

Personally I'll be pretty gentle until we get cabin secure and a bit faster afterwards if I think it'll get us away quicker. The crew down the back are 100 odd feet from the centre of the turn so its best to wait til they sit down.

Always worth remembering that the 747 nosegear has only a couple of the (up to) 400t odd of weight bearing on it so it can be a bit skittish in the wet (F regulars will hear it slipping).