NSF tyre losing pressure

[sjw]

Lately, about once a month, I'm getting the TMPS warning that my NSF tyre is low. I pump it up, and it's good for 3 or 4 weeks, and then it needs doing again. The roads on my commute are pretty bad, could this be a slow puncture? Do tyres just lose pressure if you're constantly catching imperfections in the road surface etc? I've never really thought about it before

[SRGTD]

How much air is it losing and over what period?

Have you checked the tread and both the inner and outer sidewalls all the way around the circumference of the tyre to see if there’s anything like a nail, screw or sharp stone embedded in the tread, or are there any cuts that might’ve be causing the air to escape? Also, if you’ve hit a pothole or similar road imperfection hard, then you might have buckled your wheel and in extreme cases, that might unseat the tyre bead from the rim of the wheel so it no longer forms an airtight seal. Impact damage can also cause bulges in the tyre sidewall at the point of impact, and a bulge is usually a sign that the tyre sidewall has been weakened at the point of impact. That type of damage won’t be visible if it’s on the inner sidewall, unless the car’s raised up or the wheel’s removed to inspect it. Another possible cause of air loss is a faulty tyre valve.

Whatever the cause of air loss, I’d get it checked out - the fact that it’s leaking air is usually a good indication of some form of damage that ought to be rectified sooner rather than later.

Hopefully it’s no more than a simple slow puncture that’s in the central section of the tread, in which case it should be repairable.

[sjw]

It's about 5-6 PSI over the course of a month. What's the best sort of place to go to? The nearest tyre place is Kwik-fit, but I'm a bit wary of them

[SRGTD]

I wouldn’t use Kwik Fit either.

When a thought I needed a new tyre last year, I did some research on tyre places in my area to find those with good reviews (I know, that not all of the reviews may be genuine, so they need to be treated with a pinch of salt). I also looked on Black Circles website at reviews of the tyre fitting places classified as Premier Garages, plus I did a separate search for customer reviews on those independent Premier Garages. I found one that was reasonably close to me and they were very good. If they have a touchless tyre changing machine, even better, as that should minimise the risk of any damage being caused to your wheel.

I’d recommend that whoever you go to, you make sure your wheels are clean and you get the tyre fitting place to agree the condition of the wheels before they start work (take photos of them while on their premises if you feel need to). Check the wheel with the problem tyre on it over carefully before you leave their premises too. That way, if they were to damage the wheel when they remove / refit the tyre, then it’d very difficult for them to deny having caused the damage. 

Overkill? Some would say so, but I’ve read of enough cases on forums over the years of owners alloys being damaged by careless or inexperienced tyre fitters, and if they know you care about your wheels, hopefully they will too.

[fredgroves]

I take photos of the wheels before i hand the keys over.

Saved my bacon once already that has...

[wolly440]

Take the wheel off, fill the bath with cold water, dunk the wheel in and look for air bubbles. This will show up any slow punctures, cracks or leaking valve.

[Finglonga]

Spray bottle with strong washing up liquid solution, spray it on liberally and you will see bubbles where the puncture is.


Remember to wash it off after.

[Lordie]

Are you always checking the tyre pressure when the tyres are cold?
If you tested them cold and then warm that could account for the pressure differences.

[monkeyhanger]

Saved my bacon once already that has...

Do they have bacon on Dagobah? 

[fredgroves]

Saved my bacon once already that has...

Do they have bacon on Dagobah? 

Not any more, eaten it I have