B737-800
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Workload; Troubleshooting
Aircraft Equipment Problem Less Severe
Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition; General Maintenance Action
Aircraft
At approximately 7 hours into our flight and immediately prior to my break as First Officer (Pilot Monitoring); we got an intermittent amber annunciation for 'Tire pressure;' on for 5-10 seconds and then off again. Upon immediate check of the gear synoptic; number 6 tire pressure was fluctuating between 173 and 172 while all other mains were between 215-235. Just then; the Captain returned from his break. My changeover brief included this issue. While I was showing him our indications on the synoptic; we saw the number 5 tire at 215 intermittently go amber also. At this point; I left on break. I returned from break about 50 minutes prior to landing and was thoroughly briefed by the Captain (Pilot Flying) regarding the situation and the plan. As we approached the field; the Captain told me he would like to have the ARFF (Aircraft Rescue and Firefighting) equipment standing by as a precaution. To ensure ARFF would be available; I immediately [advised ATC]. Approach and landing to XXR was uneventful. We stopped on the runway. Maintenance came out; told us to shut down the engines so they could inspect our tires. They said there was no visible damage to the tires. A few minutes later; a tug came onto the runway and we were towed to the gate. The item was written up in the AML (Aircraft Maintenance Log).
B737 flight crew reported low; fluctuating tire pressure on two tires; but were able to land without incident.