Mine was patched on the very outer tread block...had it been the sidewall, I wouldn't have bothered, but the tire didn't have that many miles and I guess I was taking the easy way out.

Live and learn...

The reason many tire shops won't patch or plug
 

or will only plug and patch is liability. Their insurance won't cover it. Throw in high speed driving and your insurance may not cover you.

Last nail I had was in my SUV which has a full size spare. That was where the plugged and patched tire went and remained until I replaced all 5.

Been there at high speed when a tire failed. I don't try to save money on tires.

I am wondering about heat loads at the centre vs. closer the sidewall. Maybe that is why mine was considered no problem.......it was done an PCA inspection centre so.....what is considered too high of a speed for a patch or is it one patch means a loss of one speed rating as suggested below

The patched tire holds air better than the all the others......two brand new PS2 to replace two new PS2s...ouch ouch! Might be better off with just having dedicated track wheels/tires