I'm trying to replace my front discs and pads, but can't shift the torx screw that holds the disc in place.

My T50 jumps out and my T55 seems way too big.

Any suggestions?

I believe T50 is correct. Maybe seized, a soft mallet will probably help.

Thanks. In that case, maybe I need a decent T50 socket and an impact driver.

I normally drill them out at work if they are stubborn/rounded off and leaving them off. It's the wheel that holds everything in place after all. That screw is just to stop the disc flapping around when you take the wheel off and frightening the life out of the average driver.