I've came accross a pair off= SSR mesh 15x8J with an offset of +1, I'm not sure what the +1 is?
Would these fit the 280zx rear perfectly?
What will be the best tire for this wheel?
If not whats the best combo for 15" wheels?
Attached pics if you have this setup.

 

These are the wheels in question:

 

The surface area where the wheel meets up with the hub (against the disc brake rotor) is the point that offset is measured. If that point is exactly in the middle of the wheel then it is considered zero offset. +0

That wheel is only 1mm further out from center. That bring the wheel in just a tiny bit. That will fit great.
The rear of a 280ZX is very wide. You can fit much wider wheels if you wanted to.
For that wheel, I think 225/55/15 would be a good fit.

If you want as much tire width as possible, try 245/50/15

http://www.rimsntires.com/specs.jsp

 

Well I'm really struggling to find a pair/set of SSR wheels so I think I will go with these.

From your information, I guess something with a negative offset would be ideal for the rears?

 

Those wheels look fantastic yo

 

I'm running 9.5 with -19mm spacing and they fit perfectly. Need to roll the fenders with 255s on the back