I have an adroid tablet in my car, and the volume it's volume is in the range on 0-30,
It is very low since the last tablet (not an android tablet) had a range of 0-60.
How can i raise the maximum volume to 60? will I have to root the device?
Maybe you can with root, but if understood correctly I think you're wrong in the basic of your question: A device has a maximum volume (which can or cannot be achieved regularly) and the possible range is being split into a numbers range that will allow you to choose.
In your case, if you'll root and be able to change the range, it will do one of the following:
 Maybe it will be possible with root to increase the maximum volume by reducing the sound quality - but that's not what your question asks.