I picked up my car from the shop in LA and went to Long Beach on Saturday night. Assumed 32 PSI all around and went driving around Long Beach and left for the Bay Area at 4pm. The light turned on around 6-7pm between Buttonwillow and Kettleman City (can’t remember). The light came on but I didn’t know the rate of deflation. I *think* the light comes on at 28 PSI, meaning I lost 4 PSI since the time that I hit the nail.
Work has been really busy as well so I didn’t address it for a full 48 hours.
Tuesday 12pm after parking at work, I see that it’s ridiculously flat, enough to warrant fairly immediate action. I actually waited until I got off at 8pm and my emergency kit measured about 10 PSI. At that low of pressure I don’t see any reliable readings. The other tires measured 32 (factory) and 32 at the gas stations (yes, I used 2), but 36 on my emergency kit, so I assumed my meter was +4. I also obtained another meter, with an offset of -1. I figured it was in the low 10s. I pumped it up to 34.
Wednesday morning at 10am, the light wasn’t on. That means it lost less than 6, assuming the light triggers at 28. However when I get off work at 7pm, the light turned on – confirmed the leak. I measured it at 26. In just about 24 hours, it lost 8 PSI.
Using this PSI deflation rate (which is totally inaccurate due to weather, road conditions, speed, etc) I tried to backtrace the series of events that led to this. Losing 4PSI in 12hours meant that I hit the nail Sunday morning around 6-7am, which is the time we went from the hotel to the marathon, which makes sense! So here’s an orderly (and probably errorful – deflation isn’t constant, etc) list:
- Sunday 6-7am (32 PSI): Hit nail
- Sunday 6-7pm (28 PSI): Light comes on
- Monday 10am: Estimated 23 PSI. The tire probably still looked normal at this point.
- Monday 9pm: Estimated 19 PSI. Too tired from work and too dark to see anything.
- Tuesday 12pm: Estimated 14 PSI. Obviously very flat, but not dead. I wait till off-work to address the issue. Too bad that doesn’t occur until 8pm…
- Tuesday 8pm: 12 PSI? no accurate reading at this point. Pump at Chevron (free) to “20”, but it doesn’t go further. Pump at Valero (it works!) to 34.
- Wednesday 10am: Light not on, so still above 28 PSI.
- Wednesday 7pm (26 PSI): Light on. Estimated 8PSI/12hours deflation rate to figure stuff out.