Hello, so I was going to park my 99 FD and right before I made it to the space I heard a slow popping noise like a seal was being broken it was then followed by this strange hissing sound near the back left of the car and I assumed it was the back tire. When I went to check on the tire I did not see any issues. Now before I parked the car I noticed that the noise would get quieter the slower I went. Can anyone give me some answers on what this issue might be?