That's a highly personalized question with a huge number of answers depending on your experience, or lack of, what type of camping you wish to do and other factors. You'll find better information on the
ADVrider forum. Here is a motorcycle camping checklist you may find helpful. You can un-check or add items to the list, then print it out to help you organize.
http://www.micapeak.com/checklists/mclist.html There is a link at the top of that page for other checklists as well. The size of your group will also play a part in how useful answers are. If you just have 3 riders on 3 or less bikes, wild camping is more possible than if you have a larger group that will be noticed more easily.
Consider the following questions to answer for yourselves to help decide what gear you need:
Do you have experience camping or is this new to you?
Are you going to wild camp or camp in designated campgrounds? (this also helps you decide how much water to carry)
Are you going to cook at camp, or pack up and eat store or restaurant food? (cooking needs could be as simple as boiling water and utensils)
How long does your rear tire last? Depending on what you are riding and the tire you choose, you may not need to do a tire replacement. Many motorcycle rear tires will last over 16,000 kms.
Typically if you need a tire during a trip, you are at the mercy of what ever shops you can find close to you. You'll pay much more for the tire, and possibly more for the installation. Not to mention hoping they have something in stock in your size where ever you end up needing a tire. You might want to change your tire(s) before the trip to start with fresh rubber, even if your tires are not worn out when you want to start your trip.
I carry the tools required to remove my wheels myself in a parking lot. I have parked in the dealership lot off to the side or around the back, removed one or both wheels and carried them into the dealer or shop to have new tires installed. Then re-installed the wheels myself in the parking lot once the new tires are mounted. This saves me a lot of money and in many cases, is the difference between waiting all day or having my wheels back with new tires mounted in an hour or less. It takes up a service bay to wheel your motorcycle in and remove a wheel, instead of just work at the tire machine.
The Wing guys often just carry a blanket and lay the bike on it's side to remove the rear wheel. There are probably youtube videos for this.
If you haven't removed your own wheels yet, you will want to practice this before your trip and make sure you carry the tools you need to do the job, understand the hazards and write down any torque specs so you have an idea of how tight things should be.
You might want to ask these questions to the Gold Wing Road Riders, HOG, or one of the other group more geared to touring and camping.