So I allready knew a few months ago that I had a puncture since it was losing a little bit of air. Now however it has begone to lose air more quickly so i've been to my local tire shop and he tried to fix it, only to find there were many (8 or so) small punctures around the sidewall and eventually he also put that tire foam to tighten the small holes. I asked him how this could happend and the only explenation I got was because of underinflation it could rub the sidewall and make a puncture?
Since this is impossible because I check my tires every month or so and add the appropriate pressure, he wasn't able to give me another reason.
He said that if it was going to fail again, I had to buy another tire but before buying a new tire, can someone maybe give me a reason how this could happen so I can avoid it in the future?
The puncture is there were the tire is getting a round edge, so not really on the sidewall but not on the contact patch either.
This is to give you an example where they are:

Since this is impossible because I check my tires every month or so and add the appropriate pressure, he wasn't able to give me another reason.
He said that if it was going to fail again, I had to buy another tire but before buying a new tire, can someone maybe give me a reason how this could happen so I can avoid it in the future?
The puncture is there were the tire is getting a round edge, so not really on the sidewall but not on the contact patch either.
This is to give you an example where they are:
