I always find and mark the leak before taking it in. Last time, like I said, I just had new tires put on to be done with it. Don’t remember what kind of nail but was pretty close to the sidewall.
I’m not an engineer, but I am a 35+ year automotive tech with a lot of tire repair experience…
Putting a patch-plug to close to the edge of the tread puts the patch in edge or over the edge of the tires sidewall area, now a tire is round, plus the sidewall is rounded also, then as the tire rotates going down the road and the bottom of the tire is flexing (ever see the slight bulge at the bottom of the tire) and now you have multi curves with the patch in that area is flexing a lot and can/will pop the patch loose and that can cause a sudden loss of air and possible blowout, so yes it becomes a highly possible safety issue and that is when the lawyers get involved in things…
And YES, I have seen many patches to close to the sidewall come loose and suddenly deflate… I have seen and delt with more flat tire than most people, thousand upon thousand of flat tires over the years, at times 20+ a day easily…
This is from the Tire Industry Association, they set the standard for the automotive world, in the USA anyway… (dealerships play by their own rules)
Tire Repair - Tire Industry Association.
As always, Capriracer can explain it, as a tire engineer, much better than I can…
BTW, we ALWAYS tried to repair 1st, and techs had much rather repair over replace anytime, repair pay a lot better than replacing most of the time… The average flat repair pays the same thing as replacing all 4 tires of the same size in some/most shops…