If the front tire wears off-center, there is an adjustment that can be made. The procedure is as follow:
1) Remove the black plastic cover over the knuckle joint on the tie rod.
2) Remove the 13mm nut.
3) If you have not already made an adjustment, you should have 2 washers on the outside of the arm. Slide off the washer(s).
4) Pull knuckle joint apart. You should be able to do this without forcing anything apart just by holding the knuckle and pulling and twisting the outer arm.
5) If you haven't already made an adjustment, between the arm and the knuckle on the inside is another thin washer.
To adjust the alignment, you need to move the thin washer AWAY FROM the side of the tire with excessive wear. For example, if your excess wear was on the inside of the tire, you need to move the thin washer from inside the arm to outside the arm. That should leave you with 2 washers on the outside and none on the inside.
If you have already made an adjustment and are still having wear problems, a different solution is needed. If your excess wear is on the outside of the tire, you will need to purchase and add additional washers to the inside of the arm. If you have excess wear on the inside and have already moved all the washers from the inside, the next step is one that will require more work.
On the original MP3s, the knuckle is as shown in the pictures above. Piaggio came out with a replacement knuckle that was shaped slightly differently and allowed for more adjustment. If you have the older style knuckle, you can purchase a newer knuckle and replace it to give yourself more adjustability. If you already have the newer knuckle and need more adjustment, you'll have to explore other options. One user on MV reportedly took his tie rod into a machine shop and reduced its length. Another option might be to try to source an even narrower knuckle, if one exists...