2007 Z4 on Runflats - tramlines like crazy

I picked up an excellent 2007 Z4 3.0si with the sports package, on eBay a few months ago - awesome car, heaps of fun. It has 80,000 miles on it, and looks and mostly drives like it's just off the showroom floor.

But... it tramlines like crazy; especially when cold, the Michelin Pilot Sports have a mind of their own. After about 5 or 10 miles it seems to calm down - can't figure out if that's because the tires warm up, the electronic assist settles down, or my arm just gets stronger (actually, don't think it's my arm... I really do think it's worse at start-up). Is this a known issue? I'm going to take it in and have the tie rod ends looked at, but the tires appear evenly worn and are, I believe the factory size - 225 40-18s in the front and 255 35-18s in the rear, with lots of tread left, and are of matching brand and model.

Thanks Steven. Well, nobody else is chiming in, so I suspect it's just me, this car, these roads, my tie rods or Forces of Evil.

If the vehicle sits a lot you could have flat spotting that wears out after driving awhile. I see this a lot with Michelins because there rubber design seems a lot softer that others. Do you feel it in the steering or the seat when it starts out? You are not having any major pulling from steering or lack of power steering assist issues?

I have a Z4 2006 and got rid of run flats years ago...I had the same problems - approaching a well worn intersection I had to hold on tight - it would pull right, left...getting rid of run flats was a blessing - the car handles incredible better - I use michelins all weather now, with a donut spare and jack in the trunk.

My experience with my Z4 was the same on the run-flats. Get rig of them !!! That and a competent four-way alignment will transform the handling of the car immediately. Why do you think BMW doesn't put run-flats on the Z4M?