Honda: steering on 96 dx hatch, wheels and tires, set of wheels

Question
I recently bought a 97 hatchback.  When I test drove it i noticed a little wobble in the steering, but didn't think it was too big of a deal.  Since then (2 months) it has =become more noticeable.  It makes the wheel wobble the worst at thirty mph and never completely goes away.  I have jacked the car up and checked for excess shake from top to bottom as well as front to back and found nothing.  Trading the tires for the spare didn't seem to help either.  Do I have a brake problem?

Answer
I don't think this is a brake system issue. Swapping to the spare may be more of the direction I'd take. The key difference is that I'd suggest swapping out a known good set of wheels and tires. You could have tires that have excessive radial or lateral run out.
If this vibration is primarily while you are giving the car "throttle" I'd suspect the inner c/v joints.