To a small saucepan, add the sugar and water and bring to a boil. Remove from heat and chill in the fridge / freezer. Can be stored in a sealed bottle in the fridge for up to a month to be used in other cocktails.
For the Margaritas:
Fill the jug of a blender with ice cubes. Add the tequila, lime juice and the simple syrup and blend until smooth. Your mixture might be a bit watery at this stage, just keep adding ice cubes, 4 or 5 at a time, blending until you get to your desired consistency.
Place some salt on a small plate. Using a lime wedge, moisten the rim of your glass, then dip into the salt. Fill glass with Margarita mix, garnish with a lime wheel and enjoy.