Noise from rear of Yaris

[APS67]

Hi all,

I wondered if anyone could help identify a problem with my Yaris (06) that’s done about 29,000. When driving there’s a rhythmic knocking noise coming from the rear of the car that gets faster as the wheel speed increases, i.e. not linked to the engine revs. My first thought was that it’s a wheel bearing going on one of the rear wheels. What’s making me uncertain that it’s the bearings though is that on another car I had when it’s wheel bearing went it was more of a constant droning/grinding noise rather than a rhythmic tapping. Also with the Yaris the noise is sometimes quieter, sometime very hard to hear, and sometimes louder. Turning doesn’t affect the noise and braking doesn’t seem to make any difference to it either.

After looking at what is involved in replacing a wheel bearing on a Yaris it seems a fairly simple DIY job as the whole hub assembly is replaced as one. Unfortunately this means an extortionate price for the part when it’s only the bearings that may have gone. Anyway, before I go down the route of getting the part I wondered if anyone knew of anything else it could be or how to identify for certain that it is the bearing that’s the culprit. Any help would be very much appreciated.