Winters went on in November, the shake started in January. It only happens when the car has sat outside overnight, it is worst around 100 kilometres an hour, and by the time I am ten minutes into the commute it has completely gone. The wheels were balanced when the tyres were fitted in autumn and the summer set has never done this. Same shake every cold morning, nothing at all in the afternoon.
Look inside the wheel barrels before you spend a penny at a shop. Slush thrown up during the day freezes overnight into a lump of ice on the inside of the rim, and a few hundred grams stuck in one spot is more than enough to shake the wheel at speed. It melts and flings off once things warm up, which is exactly your ten minute pattern. A bucket of warm water in the driveway will confirm it in one morning.
Easily. Balance weights that fix a noticeable vibration are measured in tens of grams. A fist of ice is an order of magnitude more than that.
That fits the symptom uncomfortably well. Would it really be enough mass to feel at the wheel?
I am sceptical of flat spotting as a ten minute explanation on a modern tyre. In my experience that resolves inside a kilometre or two unless the car has been parked for weeks. A shake that persists for ten minutes at a specific speed and then vanishes reads much more like ice to me, or possibly a wheel weight that fell off and a coincidence about the timing. Cheap test: drive it out of a heated garage one morning, or hose the wheels off before you leave. If it is still there on a warm wheel, get it rebalanced and check for a bent rim from a pothole.
Reasonable. I would still keep flat spotting on the list for a car that sits from Friday night to Monday, but you are right that ten minutes is long for it.
Check your pressures cold, first thing, before you drive anywhere. The rule of thumb my shop uses is roughly one psi lost for every ten degrees fahrenheit the temperature drops, and between a mild autumn fitting and a January morning that adds up to a meaningfully soft tyre. Underinflated tyres flex and squirm and can absolutely produce a speed dependent shimmy that improves as they warm and the pressure comes back up. It costs nothing to rule out and half the winter vibration questions I have seen turned out to be this.
Ice in the rims, flat spotting, low pressure, missing weight. In that order, and the first three are free to check in your own driveway.
I spent a whole winter convinced I had a suspension problem, went to two shops, had the wheels balanced twice, and eventually a third mechanic found a wheel weight missing from one winter rim, presumably knocked off by a kerb or a snowbank. Ninety seconds to fix, two months and a fair amount of money to find. If it survives the ice and pressure checks, ask them to look for a missing weight before they start quoting you on anything expensive.
@flakey_test · 4w ago
The other classic is flat spotting. A cold tyre sitting under the weight of the car overnight takes a set, and when you drive off the tread is not perfectly round until the tyre warms and relaxes. Softer winter compounds do it more than summer rubber, which is exactly why your summer set never behaved this way. If it is this, it goes away gradually over several minutes rather than suddenly, and it is worse the colder the night was.
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