# Maximum torque on thin walled aluminium shaft

I am trying to determine the maximum torque that can be applied to a 6061 Aluminium tube with O.D. = 55 mm and I.D. = 53 mm. The yield strength of 6061 Aluminium I have taken as 55 MPa and using the formula $$T = \frac{tJ}{r}$$ and the polar moment of inertia of a hollow cylinder $$J = \pi\frac{D^4 - d^4}{32}$$

This comes out to 247 Nm. I'm highly skeptical of this number as it seems quite absurd that an aluminium tube with a 1 mm thick wall can handle that much torque.

It's been quite a few years since I've done mechanics so I'm sure I'm missing something (or several things).