The bolts are certainly strong enough even a lower class of bolt in steel. But the bearing strength of the aluminum wall is not sufficient. I say this without knowing what kind of aluminum you are using, but assuming a weldable 6061 in a moderate temper.
 
The "cold" is not a problem as N2O is generally not used as a cryogenic liquid but as an ambient temperature liquid.
 
So the critical factor is bearing strength here, often true with aluminum cases with bolt circles.
 
bearing load maximum  =  wall thickness x bolt diameter x bearing strength
 
Bearing strength for 6061 in American Standard units is 20,000 psi for condition T6
 
You need to exceed the load divided by the number of bolts in bearing strength.
 
If you need more help just ask.

Hi all, a new poster to the forum
I am part of the ucla rocket team, we are currently looking at designs for the tank to hold our N2O, as the oxidizer for our fuel. We are wondering if carbon fiber is a resonable tank material? If it is, is the weight saved worth it? If not any suggestions on light-weight metal tanks that would get the job done for us?
 
Thanks for all your help,
Kurt

Simple answer- go to Rich Nakka's site and download "Casing" which is an excel utility for analyzing strength of pressure vessel walls.
 
Plug in your numbers, out drops the pressure rating along with a few other useful numbers.