Wear a belt when going heavy bro. Especially with a back injury.
When doing regular weight you don't need one and it will help all the core muscles strengthen and get used to working with the weight.
I always wear a belt no matter what weight because I have a back injury. Than again, 225 is "light" for me. But it is really a lot of dead weight on your back regardless of how much you can do. I believe in the belt, lol.