Date: 201512
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
Aircraft component: Main Gear Tire
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance
Detector: Person Flight Crew
When detected: Pre-flight
Result: General Maintenance Action; General Flight Cancelled / Delayed
Contributing factors: Aircraft; Procedure
Primary problem: Ambiguous

Narrative: On preflight [at departure airport] I found a tire showing cord on the shoulder of the tread. The center of the tire showed tread worn to 0. I called [maintenance] and told them that I was concerned because the excessive wear in the side location indicated to me a tire that either was run at low pressure in the past or still is low as normal wear would be in the center of the tire tread.Contract maintenance arrived and advised me that [maintenance] instructed them to check tire pressure and if it was up to specs to sign the aircraft off to continue operating until the evening where it would be changed on the overnight [at airport ZZZ]. Contract maintenance found the PSI to be 195 which was 5 PSI below mandatory tire change so we had to change the tire. We had no carbon brake tires [at departure airport] and were delayed more than 5 hours for a tire to be flown in.1. The logbook showed an airworthiness inspection [at airport ZZZ1) the day before and flew only to [our departure airport]. The log also showed an airworthiness sign off in ZZZ1. I was under the impression that our maintenance procedures were to replace tires when inspections show 1/16 inches or less tread. There is no way that that tire would have had anywhere close that much tread when signed off. I know it is cold in ZZZ1 and changing a tire at night is probably not a mechanics dream job; but as I remember the procedure is designed to prevent delays like we incurred. Some mechanics need to be retrained on tire inspections and if they don't want to follow procedures let's find somebody who does.2. I believe the only reason the tire PSI was below spec was because of the low temperature [at our departure airport]; had it been only 5 PSI higher [maintenance] would have directed that the tire be signed off and I would have been the voice of reason that would have refused the aircraft and cause the delay. Perhaps the tire wear was acceptable down line as written; but the wear was not indicative of a properly operated tire and in my opinion I could not depend on its internal structural integrity. We are operating aircraft not John Deere tractors; the traveling public is paying for a higher standard of safety than maintenance intended to deliver. A preflight should not be where something like this is caught it should be for unexpected anomalies not catching shoddy maintenance.3. We should have spare tires for any aircraft configuration expected to operate in a station. We looked like an amateur third world carrier to our passengers when we can't even change a tire.




Synopsis: B737 Captain reported taking a delay for an underinflated tire that he felt should have been changed earlier in the day.