The tire sealant and air compressor were put to the test today. My wife was driving the car and accidentally hit some debris in the roadway. She didn't see the offending object (it was dusk and happened just as she turned from one street onto another) but heard it beating the underside of the car momentarily (it must have stuck in the tire and then released) and the tire quickly went flat. Good thing she was close to a well lit parking lot.

I arrived and went to work, first reviewing the manual instructions and then dived right in. Removal of the valve stem with the supplied tool was a breeze. Squeezing the sealant into the tire (hand pressure, no propellant) was easy as well (even though I drew some puzzled stares from people passing by). The compressor was easy to hook up and get started. Problem was that the puncture was pretty large and it took 15 minutes of use just to get enough air into tire to be able to drive on it (the instructions say to drive 10 minutes to distribute the sealant). All the while, the sealant was running out of the puncture and running across the parking lot. I couldn't understand how it would seal because it has the consistency of milk (actually more like half and half).

Finally got enough air into it to drive around the parking lot, only to hear air continue to rush from the puncture amid bubbles of heavy cream. Tried more air and driving...still leaking. More air and driving...still leaking but better. More air and driving, etc. Finally, after working on the flat for probably an hour total, the air leak was down to a faint whistle so we high tailed it for home with me following. We made it home and the tire is still inflated 3 hours later (I'm sure it will probably be flat tomorrow morning).

Verdict is that the sealant and compressor works, but is a time consuming pain in the rear to use...and after using it, I have decided that I prefer the "old school" way...I want the spare tire.

Oh, and the tire? Naturally the puncture (more like a cut and not a nail or screw puncture) is on the edge of the tire, between the last radial groove and the sidewall (but closer to the very edge of the tire) so it is most likely not repairable. Shame, because the tire is like new (10,000 miles) and according to the dealer there isn't any road hazard warranty on the tires that came on the car (Michelin Energy s8's). The best price I can find locally is Costco at $158.00 plus tax. OUCH.