[E3Ghost]

Thanks for the comments and suggestions.

After resetting the tpms from a cold start, the resetting process moved past 1%: it reached 49%, stalled for awhile, and then displayed a "TPMS failure" warning/error. After another rest, it happened again (got to 49%, stalled for a few minutes, and then displayed an error).

I checked the receipt: TireRack sent the correct 433 MHz sensors. If the sensors were incompatible (or if all four were broken), I assume that the reset process would fail right away instead of proceeding to 49% completion. Am I wrong to assume that?

After a search, I found a couple of examples of folks reporting the "failure at 49%" problem. At least one person addressed it by increasing the air pressure on the front tires, which they had initially inflated on the low side (high 20s). But that's not an issue with my setup: I inflated both the front and rear tires to spec.

One more thing: I moved from the factory-delivered square set up on my car (225/40 18 on all four corners) to a staggered set up (225/40 18 in front and 245/35 18 in rear). Given that the staggered set up was also a factory-offered configuration for the m235i (in fact, I believe it was the default), I doubt that the change in rear tire size is a factor. But perhaps it's contributing to the problem somehow.

I continue to welcome stories and suggestions. I'm hoping to avoid an expensive trip to the dealer.