Thin mtb tyre wall
 

Hi this is my second post I bought some used Bontrager acx B 26x2.2 tyres however they are very light and the side wall of tyre is very thin almost paper thin what type of tyre is this and what terrain are they for.
https://cimg5.ibsrv.net/gimg/bikefor...61b6ff7ac2.jpg

It looks like a lightweight all around tire. Nothing bad, nothing exceptional but a seemingly decent enough tire. Hopefully you didn't pay a ton for some old tires that were sitting who knows where and look worn.

They look like suprelight XC tires, probably tubeless unless old or used. I have a friend who raced them some years ago and they treated him very well. IMO, their light weight will make them easier to accelerate and reduce rolling resistance at the expense of durability in more severe terrain.

Light XC tires. Not surprising. They puncture easily.