If you are designing a map you plan on overlaying over google maps or virtual earth and creating a tiling scheme then i think what you are looking for are the scales for each zoom level, use these:
Terrain MapType has always less zoom levels than roadmap or satellite. When you switch on other maptype you will be able to zoom to higher levels. Check in on main google maps web site. Zoombar is changeing when swithing terrain overlay.
Best Answer
Please try following code. It might help you
When you instantiate a google maps object using: new google.maps.Map(domElement, options)
You can can use options to set (among other things) the zoom level.
The default zoom level can be set using { zoom: 14 } for example.
After you create you google maps object, you can change the zoom level using setZoom()
Detail please click here