[Efthreeoh]

When the E90 first came out in 2005 - 2006, for the sport package at least, the only run-flat tire available was the OE REA-50 Bridgestone. My original tires lasted barely 26,000 miles, just because they are performance summer tires with a soft compound. I started a 175-mile daily commute right about the time the original tires were spent, so I went with a square set up (vs. staggered) on 18" rims. I also switched to non-run flat high performance all season tires in a 235/40-18 IIRC (I've since switched back to the stock 17" 162-style wheels). I've run 13 sets of tires since then, but the last two sets have been back on the OE wheels, so 11 on the square 18" set up, and now 2 sets on the 17" staggered set up.

My observations have been this: The OE Run-Flat Bridgestone summer performance tires are great tires with a lot of grip and a smooth ride. I'd have kept running them if I wanted to drain my bank account. The only downside was at about the 18,000 mile mark they get really noisy. When I switched to the 18" non-run flat square set up on high performance all-seasons, I got over 35,000 miles a set (rotating every 5,000 miles). The trade off for me was a small decrease in handling performance and no noticeable increase in ride quality with the non-runflats (but I went down 10MM in sidewall height at the same time). At 182,000, I replaced the struts and shocks with OE BMW sport suspension components. I had the car aligned (for the first time) and that was a complete mistake since I couldn't find a shop that knew how the fuck to align a BMW. I went through 3 sets of tires very quickly (around 20K miles a set), until I finally a) I changed back to the '17 stock wheels, and b) took the car to a BMW dealer. That set the suspension straight again and I got 38,000 miles on the first set of new tires post alignment and the I just got unbelievably 49,000 miles out of my last set (Yokohama ADVAN A/S 3). I just replaced those Yoks with another identical set, but I redid the suspension again, moving to Bilstein H8's with H&R springs. I had the car aligned at a local shop that works on BMWs (the owner races them). And yesterday I rotated the tires at 5,000 miles and they are wearing evenly and dropped only 1/32th in tread depth. The most recent alignment didn't change the rear setting (I marked the bolts) and the front I finally put in new lower control arms and tirerods (after 336,000 miles). Again, moving back to the 17" OE wheels and now on non-run flat all seasons, I've not noticed any real discernable change in handling, braking or grip.

All that said, I've figured out that a 35-series tire (sidewall) in an "XL" load rating gives almost as good run-flat performance as real run-flats, for a lot lower price. I ran one of the 18" all seasons at zero pressure for 30+ miles once to get home.

Lots of words, but that's been my experience with tires on the E90.