Always carried a Continental TireFit kit in our S. Never had to use it but we always swap run flats if we have them on the car.

I haven't switched to regular tires on the S450 yet, but I put 170,000 miles on a Lexus sc430 without a spare. I did keep a plug kit and small pump in the well.

I was never that concerned. TPMS sensors give you a lot of warning if you have a leak -- often enough to get to a station in time. In the event of total tire failure, you have a phone. But, flat tires are pretty rare these days. To be fair, I also never wait until I hit the treadbars before I replace my tires.

I don't carry anything as I run run flat tires but a tire repair foam might save the day

I have the Conti puncture repair kit. (Have not used it)

I also have a repair kit.

But currently looking into Armour Seal that you add to you tyres prior to having a puncture which acts like the repair kit and seals up to 15mm apparently.

I have had cars without spares and no runflats since 2008/9 and, touch wood, have had no punctures.

I carry a spare

On my previous MB I switched out my Run Flats for Michelin Pilots when they showed significant wear after 12K miles. I bought a Slime Kit to put in the trunk. I kept the Slime Kit when I traded up to the S450 and plan to switch the tires after they start to wear.

I had run flats on my BMW and blew one on a nasty concrete lip on the freeway. They still had plenty of wear left on them but it was my excuse to get rid of them. I drove straight to the nearest America's Tire and swapped them out for Michelin Pilots. Night and day difference in ride. The car has no spare so I carry a can of tire foam and keep my AAA card handy. I'll be doing the same with the Benz.

I run with the run flats, and have a compressor and sealant in my trunk.

I keep my suspension in the S mode all the time and my staggered tires look brand new at 18,000 miles. just sayin''

Check your kit, some have expiration dates on them...

What tires? I'm disappointed with the wear on the OE 18" Turanza run-flats.