So, I finally made decision to ditch the run flat tires. The main sticking point on waiting for me was the lack of a spare / what to do with the spare tire. So here's what I had on my '11 cooper S manual:
R111 Black Star Bullet ET48 (17") with all season run flats combined weight: 42.4 lbs
Replaced with 16x7.5 Kosei K4R LT GREY with 205/50R-16 Kumho Ecsta 4X combined weight: 33.5 lbs!
Plus I ordered a spare from the mini part store.

When I took off the wheels to mount the new ones I found that both wheels on the left side had a pretty large ding on the inside (I'm pretty sure I know which jerk pot hole did it too ). Another had a nail in it. The fourth one was one that a guy had used his teeth to mount/unmount when it had gotten a flat a few months ago. Awesome help rationalizing the money spent.

The ride is different in two notable ways. First, my butt hurts wayyy less. It is immediately and definitely notable. But, you the ride is definitely more squirrelly under quick handling. I also expect to get a bit better fuel economy / acceleration (probably not at the same time) with such a large weight drop at each corner. I suspect any difference I've been feeling in acceleration is all psychosomatic. But hey – maybe I'm faster. I haven't gone autocrossing yet – I did like that the run flats made crazy noise before the lost grip. I'm guessing non such hints on the regulars.

I'm not really sure what other people do with their spare but I found it unacceptable to put unto the trunk. It fits well but rolls back and forth – very annoying. It actually wedges very well behind the driver's seat and on the rare occasion when I have a 4 passenger it still does fit into the trunk. Does anyone have a good solution for fixing it in place in the trunk?

My best decision for all of this was http://www.bimmerzone.com/BMW_Perfor...-SST-TOTE.html . It fits well but also expands to fit a full sized wheel to keep my car clean. And it was cheap!

Anyway, I hope that fills some gaps in the information that I couldn't find when I was making my decision!

-Alex

 

I too switched from RFTs to "regular" tires shortly after I got my MINI and haven't regretted it one whit. Most of my miles are urban/suburban, so I don't carry a spare. For road trips I have AAA + slime + cigarette lighter-powered air pump, but I totally get carrying a spare. As long as you have a backup plan & aren't caught unprepared, it's whatever works for ya.

You may know this already, but it could take 500 - 1000+ miles to scrub the slickery compounds off your new rubber, which could contribute to the squirrelly feeling. After the break-in period your tires might feel stickier, grippier; hopefully so.

Happy Motoring!

 

just got back from having my runflats replaced with 205/50R-16 Kumho Ecsta 4X also. Wish I wore out the runflats sooner.lol

 

@friday - hopefully the mold release wearing will help. After a quick left-right maneuver it feels like there is some residual motion which could be the springier sidewalls.

 

The increase in sidewall height from going from a 17 to 16 also adds the squirley feeling, as well as the decrease in sidewall stiffness from a non run flat sidewall.

 

Best way to de-squirrel your MINI is with at least a 19MM adjustable sway bar. 22MM even more so.