I did a search and couldn't find the answer.

I have a 94 F150 Flareside. I want to run either a 31x10.5 or 33x10.5 on the stock 15x7.5 wheels.

Can i do that without any effects on the ABS or computer?

The suspension is stock as well.

 

I'm not sure about clearance on your truck, but you can mount them on those wheels without any problems. It will not affect your ABS or computer.

 

4x4 or 4x2?

31's should fit either truck with no problem.

33x10.50's might fit on a 4x4. You would need to test fit them. I think it is the width more than height on these trucks that causes rubbing.