1) Download latest DRC file from this page and save as .RUL (use 'Save link as ..' if necessary)

Latest version: DRC_V16p2.RUL

Changes: 
	Max trace width 500mil
	Max hole size 152mil
	Silk to Solder Mask Clearance 5mil

2) Open your project
	On the top Menu select: Design >> Rules ...
    On 'PCB Rules and Constrains Editor', Right click anywhere on the left column
    Select: Import Rules
	    Select all rules in window (using shift and the mouse),  --> OK
   	    Browse for the .RUL file to load
  	  	Clear existing rules prior to import? --> NO

This will load the new rule file and preserve any custom rule you made, like for example routing rules for track widths. 
However all basic rules - with default names - will be over-written.

3) Click on Apply