I am pretty happy with my run flat tires on my bmw, even after a blowout they remain normal and handling is near normal as well, plus you can drive like 100miles and 50mph to a nearest tire shop. The only downside is they are more expensive and sometimes if you cought nail close to a tire sidewall it means you I'll have to replace a tire since it's not fixable
And they ride more harshly, are less compliant, are heavier (look at how much some spend on light-weight rims; tires are even further from the center of the wheel), more expensive, can get bent / dented, and rely on finicky tire pressure monitoring systems.
I used to replace a lot of run flats on BMWs and they are all of that. Plus because the sidewall is so thick they're a huge pain in the ass to get on the rim so chances of rim damage is much higher when you put these on. Even with helper arms on the machine they're still difficult.
The thick side wall makes for a bad ride in my opinion. The difference is pretty significant.
Beyond the issue with unsprung weight, that seems like a truly awful trade-off. A run-flat still needs to be serviced if punctured and is still vulnerable to sidewall damage and potential blow-outs. If you carry a full size spare (I sure do) in the event of most tire failures, you still have the ability to get much further down the road with less drama.
None of the new sedan vehicles carry a full sized tire, they all carry a temporary one, which can only be driven 50 miles at low speed. So still worse than broken run flat
They don't come with one stock, sure, but there's nothing to stop you from going and buying the correct sized steel (or cheapo alloy) wheel and a decent tire that's the same size as the ones on the car and carrying it with you (and throwing the junky temporary spare out). Yeah it requires you to work a touch extra on the setup, but it is worth it. The extra full size spare will cost about the same as going with run flats vs non-run flats each time you swap out tires.
If you're interested, it's pretty easy to get the correct sized wheel from somewhere like RockAuto or Discount Tire Direct.
I have a 5 series bmw (f10 latest one), and I have had other premium cars before and I (and many car experts) can tell you nothing comes close in this price range in terms of handling and comfort of BMW, run flat tires make no difference for me compared to regular tires on my previous Merc and my friend's audi a6.
Why downvoting? It's my personal experience and opinion? Sometimes I don't understand HN users...
I didn't downvote you, but I'd guess the reason was that you brought an irrelevant fact to a discussion about run-flat vs regular tires - it doesn't really matter if a BMW with run-flat still has better handling than an Audi with regulars.
I was also under the assumption that if you actually drive the 50-100 miles on your run-flats after they've been punctured, then the tire will be so damaged as to require replacing.
I have run-flats on my Mini, and the Mini community very adamantly insists that regular tires are smoother, quieter and offer much better traction. I plan to make the switch soon.
