Large vibrations at the front of the car that then dissappear

Question

In my 2003 Honda Civic, whenever I first join the motorway and get up to a speed around 60mph, I experience a large constant vibration that seems to be around the front left side of my car.

As speed increases the amplitude and note of the vibration also increase (the note only increases with speed not rpm). It is enough to make me drive at 60mph max. After a while it seems as though the point of the vibration can move to somewhere between the front wheels.

Finally, after about 20 minutes driving, the vibration will disappear and I can drive normally.

This has now been consistently the case for the past 3 months. Are there any ideas as to what this might be or how I can go about diagnosing it?

Answer 1

It could be one of several things:

1. Thrown belt in a tire. The makeup of a tire consists of belts which are wound around the tire inside the rubber. These provide support for the form of the tire. If the belts become delaminated inside of the rubber, it is sometimes called a "thrown belt". This can cause your tire to become lumpy or appear to have an imbalance. The imbalance is there, but becomes more noticeable at higher speeds, and only gets worse as the speed increases. If, after the tire is totally warmed up, the belts somewhat realign, the imbalance can appear to lessen. You can sometimes spot an issue with the a slipped/thrown belt by jacking the car up and spinning the tire, looking for the tire to make weird pattern in the tread (the tread will appear to jutt over as the tire is spun). If the tread doesn't flow straight, there might be an issue. Also look for bulges or lumps in the tire, to include tread and sidewall.
2. Flat spot on the tire. A flat spot can form from sitting too long in one place. This can happen, but if you're driving your vehicle on a regular basis, it shouldn't suffer from this. If you have very inferior tires, you might run into this more often. A flat spot will pretty much go away after the tire is completely warmed up, though.
3. The wheel/tire is out of balance. This is less likely by your description, but still possible. The imbalance should be there regardless of the length of time the vehicle is being driven. A weight imbalance can occur if it wasn't done correctly in the first place, or if the wheel has thrown a balancing weight. A tire shop can suss this out for you.