is a set of like new condition 19" BMW style 296 wheels from my 12k SDrive35i fitted with brand new 245 and 275 mm Continental ExtremeContact ultra high performance tires, mounted and balanced, for $1989. When I bought the car I was extremely disappointed with the jarring ride quality, something road testers commented on repeatedly. I also found the car rather undertired.
After much research I purchased new 245mm tires for the front and 275mm tires for the rear and had them mounted and balanced by a top shop her in LA.
THE Z4 WAS TRANSFORMED! Prior to changing the tires I was seriously considering selling my car dude to the harsh ride and creaks that would come from the car, including the top when closed. AFTER changing the tires I was blown away by the difference, the wider / taller tires literally transformed the Z4. Its ride is now just as good as my SL600, a car that cost more than double what the BMW cost.
I then took the car for a drive on Mullholland Drive, which is about a mile from where I live and its grip was spectacular on the bigger tires.
What's also super important is the extra tire size not only dramatically improves ride quality but I'll bet alleviates the wheel cracking concerns people have talked about with the 19" wheels fitted to the Z4s. Having this extra cushion gives a more comfy ride while also protecting your wheels.
This is, as they say, a win-win situation.
I've purchased some ultra light wheels, 19" in front and 20" in rear, hence the sale of these wheels.