3-Series Killer

Hi All,

My recent upgrade from 17's to 18's has spawned a very frustrating tire issue that I've been unable to resolve. I've been told that one of my new tires are pulling (or pushing) my car to the right. Here's how the story goes:

My car (2002 A4Q Sport Sedan) has 15,000 mi. and has never had an alignment done. I've also heard that it is a good idea to have the alignment checked out when upsizing. So I dropped my car off at a local garage that specializes in alignment for an inspection. They've always taken good care of me in the past and they use all the latest Hunter equipment. As standard procedure, the mechanic took my car on a test drive. This is when he observed my car pulling to right. Again, as standard procedure, he made sure all my tires were properly inflated. Another test drive and it was still pulling right. Next, he cross-rotated the fronts. As I understand it, this is how you diagnose a tire issue even thought they're directional tires. He observed the car pulling slightly left now. He rotated my tires back and called me with the news. The mechanic advised me to return to the place that I bought the tires to have the faulty tire replaced. When I picked my car up I noticed my car was pulling right as he described. I guess with all the excitement of my new tires/wheels I didn't notice until he burst my bubble. Per his instructions I drove my car back to America's Tire to have them check it out. The radial pull pheomenon was news to me, I had always thought any pulling issues would be addressed by an alignment.

I was told by America's Tire that a number of rotations had to be performed to confirm and diagnose one of my tires were pushing or pulling. Numerous rotations and test drives later (the mechanic recalled rotating my tires at least 6 times), they determined the front right as the culprit and ordered me a replacement. Several days later the replacement arrived which they mounted and rebalanced. Problem fixed? Nope, unfortunately my car was still pulling right. Now I've taken it upon myself to figure this out. The first and only thing I've tried is rotating the front left tire with the rear left tire. Assuming the front left tire is pushing right I expected to see an improvement by rotating the left side. Well, I didn't. Now I don't know what to do.

Any suggestions are appreciated as well as answers to a few of these questions:

How common is "radial pull"?

Is radial push as common as radial pull?

Is it typically difficult to diagnose which tire is the problem tire?

Can a tire push (or pull) from the rear?

Is this a common consequence of plus-one sizing?

Thanks.