Challenger CL600
Flight Crew Flight Instructor; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 158; Flight Crew Total 14739; Flight Crew Type 4546
Human-Machine Interface; Time Pressure
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Became Reoriented; General Maintenance Action
Aircraft; Human Factors
Flew two flights with; what we perceived as a tire with a slightly low pressure; but after last landing the tire only had 30 LBS of pressure in the tire. Both pilots thought the tire was just a little low on pressure and we opted to not have Maintenance look at the tire; so we could get out without further delay. When we came back to base with the aircraft we contacted Maintenance who told us that the tire was not flyable. We didn't realize it; but we believe that the tire had a slow leak in it; but the Mechanic stated that this was not possible (news to me but he probably knows more about tires than I do.)The problem arose due to the pilot doing the inspection didn't see it as too low. After Ground Personnel asked us about it I went and looked at tire and it appeared in good shape to me. Contributing factors were schedule trying to get all flights done under Part 117 rest rule requirements.  So in order to not lose time we didn't have Maintenance look at it. Corrective action is simple; when something looks not 100% call Maintenance. We checked the tire on both flights before we took off; but we didn't see any unusual wear of see a real low tire. Even though the ground crew was again pointing at the tire. Next time when a ground crew points out the tire I will definitely call Maintenance with a pressure gauge; as they see more of the tires than I do when flying. After we taxied in after the second landing it became obvious there was not enough air in the tire to fly. On postflight we found the pressure in the tire was at 30 PSI; which is way below the 166 PSI for normal pressure. The crew was not fatigued; just not really attentive on the tire going slowly flat like that. After the fact I feel like I didn't take the safest course of action and that is why I am submitting this report; in order to warn others not to take any risks that are not needed to operate an airplane!
CL-600 Captain reports flying two legs with a main gear tire perceived as slightly low on pressure; which was also pointed out by ground crewmen. The pressure is checked after the last leg and is found to be 30 PSI instead of the 166 PSI required.