The Rocket comes standard with 240/50R16 rear and 150/80R17 front. Since you bike has the 240/55R16 rear tire size, it is a full inch taller than the stock tire. So right off the bat, the back end is a Half Inch taller than standard. By changing the rear tire to an Avon Cobra 240/50R16 you will lower the back axle a half inch.
Also you can lower the front 2 ways.
1) Change the standard front tire to an Avon Cobra 140/75R17. That size is very popular because it makes the front axle a Half Inch lower too. The turn in and overall handling is greatly improved. If put these tires on together at the same time, you will be amazed at how much better the bike handles. And you will be sitting a Half Inch lower front to back.
2) You can lower the front forks 12 MM by loosening the front tube clamps and sliding the forks up. 12 MM is all you can gain here. That is almost a half inch.
FYI: The best place to buy tires is Rocky Mountain ATV. Great service GREAT PRICES.