Date: 201603
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Aircraft: EMB ERJ 170/175 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Aircraft component: Main Gear Tire
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Time Pressure; Confusion
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Pre-flight
Result: General Maintenance Action
Contributing factors: Procedure; Aircraft
Primary problem: Aircraft

Narrative: It all started earlier in the day. We were starting our day and received the airplane from the previous crew. My First Officer (FO) did a great job on the walk-around and found that there was a cut in the tread groove of our MLG #2 tire. I looked at it and agreed. It was small; but we both saw metallic thread which we thought to be cord. We wrote it up; called Maintenance Control (MXC); and a mechanic eventually came and looked at it. He simply stated that it's within limits; but there were 'x' amount of plies in that tire anyway; so it wasn't a big deal. We didn't like his attitude toward it; but not being mechanics; we do have to trust his and our MXC's judgment.We flew to our destination without issue. I told my FO to take a look at the tire again after we arrived. Unfortunately it was on the part of tire directly above the ground when we arrived; so we weren't able to. We then flew the next leg without issue; and it had become night time. My FO once again inspected the tire and with a flashlight you could clearly see cord.I called maintenance and MXC (Maintenance Control). On the phone I spoke to a MX Controller; I told him the whole story and how I was kind of annoyed it hadn't been taken care of earlier in the day. He explained the retreading process and that sometimes cloth will be showing; but it isn't cord. I asked if there was a way to tell if it was cloth or cord then. He said there are measurements; it gets technical when you look at the manual. I then asked if the previous mechanic had taken any measurements. The answer was no.I felt a lot of pressure to not write up the tire; but I decided to anyway since it's me in the pointy end of the airplane. Not to mention the high tire speeds at various airports.The mechanics came out and inspected the tire and agreed that it was cord. I overheard the conversation between them and MXC. It was well we could replace it; but it would take a long time finding the equipment needed; etc. So they decided to sign it off for 5 flight cycles. We weren't happy about this; but we did have to trust the mechanics.Once we got to our destination without issue; we were met by a mechanic who was there to change the tire. He told us; yes it did need to be changed and there was no question about it. At that point; I got the feeling that the safest course of action wasn't chosen because of time pressure as well as pressure from MXC to keep the airplane in operation.All the while I was trying to find a reference or something in the Flight Operations books about what is and isn't acceptable as far as tire damage is concerned. Both the FO and I looked for quite some time with just some text here and there found. It would be nice to have a chart; or diagrams; or even better; pictures for us to reference. If I was armed with that sort of material I would have refused the airplane and this wouldn't have been an issue. Without it; I had to accept that the judgment of all mechanics involved was sound; and take the aircraft.I am not trying to make a mountain out of a mole hill; but I am concerned with our safety practices given all the time pressure the company is under with our subpar performance. I want things like this to not be an issue for me or any other pilot. Over the course of my almost 3 years with the company; I've seen the MX go from great; to not so great. This must be rectified as soon as possible. Maybe some tire training for crews would also help (as far as construction goes).




Synopsis: EMB-175 Captain reported there was a cut on the #2 Main Landing Tire (MLG) tire that the Flight Crew was concerned about. Maintenance considered it serviceable which left doubt in the Flight Crews mind.