Questions about transition holes on the pcb board
Assuming the dimensions are in inches, those sound like power traces.  That makes things a bit more complex.

It is a very common practice, and should not be a problem.  Note that the copper thickness inside the via is not automatically the same thickness as the traces.  Also, the larger the via diameter, the more narrow the trace width on the sides where the current is going "around" the hole to get to the back side.  And finally, the diameter of the via sets the equivalent trace width of the conducting path through it.

To start, make the via inside circumference the same as the wider of the two traces and see how that works out in your design software.  Then adjust the via diameter based on the ratio of the via plating thickness and the trace thickness.  For example, if the via plating is 1/2 ounce and the traces are 1 ounce, double the via diameter.  If that makes the via too wide, another technique is to have two vias in line.