A lot of good points here. Allow me to add a bit of personal experience.
Toyota, along with others, has gone to ball bearings for the wheels for the lower rolling resistance. Ball bearings do not stand up to impact as well as the roller bearings that manufacturers used to use. The noise you describe is classic for wheel bearing s that have seen one too many potholes.
I own a 2005 Scion (Toyota) with 209,000 miles, some of them hitting potholes. At this point I’ve changed out my front bearings (about two years ago after banging a pothole and definitely damaging one) and my rear bearings (the week before last, because I too got tired of that throbbing sound). My car now runs as quiet as it did when it was brand new.
The front bearing clearly was damaged.
The rear bearings could not be verified as damaged/worn by mechanics. But changing the rear bearings definitely did away with the throbbing. The mechanics that couldn’t verify the throbbing are good friends, highly experienced and certified, that teach a degree-bearing automotive technology program at the college I retired from. They have no interest in not being honest, and being friends and of high integrity, they definitely were. This type and amount of wear simply could not be verified on the lift, and was suttle enough to not be any different from normal tire wear noise. In a normal situation, if I didn’t know them and they didn’t know me well, if I’d have brought the car into them they would have been in honest to simply tell me they could not verify a problem and declined to change the bearings.
I wrote this because
- wheel bearing damage from one too many potholes is not uncommon
- if mechanics tell you they cannot verify the problem they’re probably being honest.
- if you have them change out the bearings anyway, it’ll be expensive, and it might NOT solve the problem. Thinks like tire wear also cause these sounds and should be eliminated as possible causes first.
What I’d suggest is to have it looked at and if the shop can’t verify a source of the sound, wait until it’s time to change the tires anyway and see if the throbbing continues. If it’s gone, it was the tires. If it’s not, you can decide whether to pay for new bearings or accept the throbbing. A level of wear that isn’t verifiable on the lift is not a bearing on the verge of failing, it’s simply wear. A bearing on the verge of failure would be verifiable.
My post may be long, but I hope it helps.