I recently went to 235/60/15 from the 215/65/15's. They're BFgoodrich radial TA's. I had some shaking in the steering wheel anywhere from 45 - 60mph and had them re-balance the tires. I still have a little shaking though around 48-51. It seems worse on the shoulderless county roads where there's more of a slant in the pavement to steer against. Everywhere else I barely notice it, and that's still only when applying slight pressure on the wheel to keep it straight in a few spots.

Are there any issues with going to this size with a stock V6 suspension and no re-alignment? I had the alignment done only a month ago, and the ball-joints etc. where checked too and still tight. (although they probably need a lube job)

Or should I explain to the place what's happening and have them try again.

My 2 front center-cap things are loose now too for some reason, but I don't think it's affecting everything else. (the lugnuts are tight)

 

Are they static balancing or dynamic balancing the wheels? Any bent rims?

 

like he said bent wheel maybe. Check to make sure that you bearings are nice and snug. jack the car up and take hold of the tire and try to wiggle the wheels. Push the front side in and the rear side of the tire out. Then back and forth.