tire leak PLS HELP :-(

[Ken from Guam]

here it goes rear passenger side. 235/40R18 i dont know whats up with it but when i put air its always the lowest of the four. I usually put 31 psi once a week. the other 3 tires would usually show 23 psi but the rear tire shows 6 psi onl yeverytime i put air. by lookin at tires i would notice a just lil diffrence from the other 3 but its not completely flat. i have been to 2 tire shop alredy and they couldn't find anything. they checked evrything and submerge it water to see if there is air leaking and all but nothing....they even checked the valve and both shops said its all good. there is a small dent on the inside of the rim but they checked that also and there no air leaking from it. what gives? any ideas? TIA


Ken from Guam

[MikeV]

This is probably not it, since you've had the tire inspected, but I once had half a staple sticking in my tread, barely visible. No air would leak unless the staple was in contact with the ground.... took me a while to find it, most of the time the tire would hold pressure, some days I'd walk out to my car and it would be down to 10psi or less - it all depended on the position of the staple when I was parked.

[Warren N.CA]

the car is driven. I would inpect the tire yourself, under a good light by jacking the wheel and rotating it slowly. Look for a nail head almost buried in the rubber.

This is probably not it, since you've had the tire inspected, but I once had half a staple sticking in my tread, barely visible. No air would leak unless the staple was in contact with the ground.... took me a while to find it, most of the time the tire would hold pressure, some days I'd walk out to my car and it would be down to 10psi or less - it all depended on the position of the staple when I was parked.

[MikeV]

BTW, for that size tire I would suggest a higher pressure than 31psi. There isn't much sidewall there.... I typically raise the pressure somewhere between 1-2psi per inch increase in rim size.

[Hector]

probably the next thing I would check is that dent in the rim you mentioned. Park the car so that the dented part of the rim is closest to the ground (the tire fully loaded at this point, I guess.) Get a mild soapy solution and pour it over the dent, and check to see of any bubbles grow. If not, then move the car so that the tire is rotated 90 degrees and repeat procedure with soapy solution. Do this for every 90 degree turn and see if something gives. This might take some time so be patient.

Hector

[Ken from Guam]

thanks for the suggestions guys...Hector, the dent is on the inner side of the rim(back side) so i have to go under the car for me to be able to access it. maybe this weekend when i get off from work ill try to it take out the tire again and check the whole tire for leak manually and patiently.....if i really cud not find anything i might as well have the dent fixed and see if it would be of help at all. hope i can hav this fixed soon, it's really pissing me off already :-(

thanks again for help guys
Ken from Guam

[Javier]

Some times the only way to find a nail is to remove the tire from the rim and "feel" the inner surface with the fingers. Some times it is even steel belt wires pushing trough the inner surface of the tire (My original Dunlop’s did it) and the situation gets worse as the tire keeps leaking and suffering from under pressure operation.

Javier