What would cause a more than average loss of tyre pressure?
Could it be down to how the tyre was sitting on the wheel. tyre was replaced a month ago. Problem only happened over last weekend.
I have standard 15 inch ford alloy wheel
Answers:
hitting speed bumps too fast, driving up kerbs and hitting deep pot holes and raised manhole covers all can cause pressure to be released round the rim of the wheel
It's possible your wheel could be buckled so that the tyre is not sealing properly around the rim
It could be leaking around the bead of the tire .
a faulty tyre gauge
heat
One cause could be extreme fluctuation in temperature
Could be that the rim of the tyre has become displaced from the rim of the wheel. Get it checked at a local tyre dealer failing that has someone let the air out of your tyre as a prank?
A slow puncture is a possibility.
It depends on how the tyre rests.
it might be escaping around the rim.
The best way to find out is to mix up some washing up liquid and water (quite a bit of detergent in the mix) and paint it onto the tyre with a paintbrush, you will see bubbles where the air is escaping.
If air is escaping then its a LEAK!
Is the rim bent?
It must be leaking somewhere.
I know you say not a puncture or faulty valve (slow punctures don't always show up in the tanks).
Could be it isn't bedded in quite right or you have a bit of grit or stone on the wheel rim. Could next door's holigan have let air out when you weren't looking?
Did you blow tyres up in warm weather and now it is cooler it looks like it has gone down?
It could be the air temperature. I don't know what the weather is like where you are but it is adviced to top up your tires in the winter as the air contracts. In hot temperatures it will expand.
If you had a spell or hot weather and then it cooled down it could explain why the pressure has gone down.
Just top it up and keep an eye on it! Happy motoring!
Have you hit any kerbs recently?
It's possible to pop the seal on the side wall.
Some garages seem to make a hash of fitting them
The only reasons that a tire would lose pressure in a short period of time are a leak of some kind, or the air being manually released from the tire. You say there was no puncture, and no problem with the valve.
I have to assume that you had the tire checked in a water tank. The best way to check a tire for leaks is to fill it full of air and put it in a tank of water. any air leaking will show up as bubbles.
It could have a bad seal between the tire and rim, or you could have been the victim of a vandal or a practical joker letting the air out of your tire!
The air is escaping because of a bad seat at the tire bead. The tire needs to be taken off and the wheel inspected. More than likely the wheel is corroded and pitted to the point that the bead will no longer seal. There is a possibility that bead sealer will fix the problem, but if not, the wheel will need to be replaced.
The area where the tire seats on the rim or the bead is a place where tires can leak and alloy wheels are even known to leak right through the center of the wheel itself. There is a bead sealant available to repair this so you might have that checked.
It could be a porous wheel - cast aluminium alloy normally isn't air-tight, so needs a coating (enamel) to keep the air in the tyre. If the coating is damaged, the air can slowly escape through the wheel.
Alternatively it could be a "slow puncture" - a very small puncture that lets the air escape very slowly, and is difficult to find, but usually easy to repair.
If you suspect its how the tyre is sitting on the wheel, check the tyre sidewall for the the maximum allowed pressure, inflate the tyre to just less that that (to be safe) with the wheel off the ground which should seat the tyre properly on the rim, and then reduce the pressure to the normal for your car.
A good independent tyre fitters should be able to diagnose the problem easily, and will probably only charge for the repair (if they can), or recommend someone else who can fix it (if its a wheel that need re-enamelled).
your wheel wants its rim cleaning, very common fault on alloys they oxidize where tyre sits,
You could have a leak arround the bead or a bad valve stem. The place I deal with puts in new stems every time they change a tire. Although there is a chance the rim is dammaged but not likely.
check the walls of the tyre for damage dodgey valve or a bit of dirt in it
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