I was checking tyre pressures recently and happened to notice the state of one of the rubber valve stems. It had perished and started to crack, as you’ll see from the picture.
A note to those wincing at the state of the wheel – yeah, I know, not pretty. My standards are generally much higher. This is my reliable workhorse – a 12 year old Toyota Hiace deliberately chosen because it was a little rough round the edges but mechanically sound. I’ll review it on here sometime because although it isn’t an import, it is Japanese (obviously) and is a fine vehicle.
Why is this important?
Back to the topic. These cracks gradually get deeper, to the point that they let air out of the tyre and cause it to go flat. This could range from mildly annoying if they leak slowly, to dangerous loss of control if they let all the air out quickly when travelling at speed.
Smaller cracks might not be visible straight away, but if you bend the valve stem slightly this should open up any smaller cracks so they can be seen. Beware that if the damage is extensive, doing this might let a load of air out of your tyre!
How to fix it?
The remedy is simple and fairly cheap – just replace the valve stem. There are tools designed to allow this to be done whilst leaving the tyre in situ. However, the most reliable way of doing this is to break the bead seal of the tyre next to the valve hole, cut the old valve off, then pull a new one through from the inside out and remount the tyre. Whilst this can be done at home, and is a job I’d be comfortable tackling, I prefer to have jobs like this done at a tyre specialist shop because I feel this is a better use of my time.
If you decide to tackle this yourself, it will be much easier with some specialist tools. As well as the replacement valve stems, you’d need something to break the bead, tyre lubricant and an air compressor (unless you really want to re-mount your tyre using butane or ether – search for it on YouTube if you don’t believe me).
Is this problem with valve stems relevant to Japanese imports?
Absolutely. This is extremely relevant to Japanese imports because often they travel such low distances that the tyres (and valve stems) perish before they wear out. Usually a new valve is fitted along with a new tyre, so if tyres are being worn out frequently, the valves won’t be hanging around long enough to perish. In the case of a car covering low distances, the tyres could be in place for years and so the risk of degradation of the tyre and valve stem rubber.