Friends, I recently upgraded my Punto's tyres to Aceleres 195/60R15 88 H tubeless tyres on 15" Linea rims. When checked air pressure after 3 weeks of purchase I saw about 4 PSI of pressure was less in the rear left tyre than other 3. I topped up all to recommended pressure 32PSI. I checked to see any leak through valve stems and found all are fine . Again after 3 weeks, I had to do one quick lane change like driving to left just at 40kmph and heard tyre-squeal sound from rear ; still the car handled well . I guess tyre squeals may also due to insufficient air pressure. Now I'm in doubt that rear left tyre may have some sort of manufacturing defect that contributes air pressure loss. I am also afraid that I saw one member in this forum mentioned about defective aceleres where air loss happens through sidewalls . Can you guys specifiy what all things contribute to air pressure loss when the car is at rest and motion and also any manufacturing defects? I will be checking the air pressure of all four tyres this weekend.