You won't have a big problem with potholes in Florida. At least not compared to the problems you will have in the NE.

As for the runflats, I hate them in general. They have been nothing but a nightmare on my Sienna. The treadware sucks (about to put on my 3rd set at 44,000 miles), they are hard to find, they are VERY expensive, and many average joe tire shops do not have experience with RFTs and the TPM systems, which leaves you going to the $tealer to fix problems. I do not know if all of this applies to the 3 series tires, but it sure was a nightmare with the Sienna, enough to make me seriously consider selling the van! Be wary!

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-'13 E93 M3 Cab, Interlagos Blue, Carbon Black leather, DCT, all options, and fun, endless fun!
-'13 X5 35i M-Sport, Carbon Black & Cinnamon, Dinan Stage 2!
-'15 Toyota Sienna Limited Premium AWD, Silver & Grey, Nav & BluRay, and less lame than the 2011 it replaced
-'07 Mini Cab S, Laser Blue, 6sp, endless fun that ended (sold)
-'04 X5 4.4i, loaded, loved, modded and sold