Disclaimer: Don't think I am unhappy with my ride. My Skoda is a wonderful car which I drive regularly most on highways.

4 or 5 months after purchase I noticed a strange noise coming from "outside" of the car when driving at any speed over 60km/h. The noise becomes very high at around 80-90km/h and then it becomes indistinguishable from aerodynamics, etc. This noise does not change in frequency or pitch with the rpm. What I mean is that if I travel at 80km/h and the engine is doing 900rpm or 2500rpm is noise is absolutely the same. It is a sort of humming, that changes intensity with speed.

That made me think of 2 possible causes to this noise: 1) tire noise; 2) wheel bearing problems.

I went to the dealer and mentioned this noise. He looked into it and said everything was ok. He then started to explain that the problem could be because of the tire itself and the way each thread of the tire was being worn. According to them it is something that happens to cars that drive a lot in highways at constant speeds.

Does this make sense? If so, where can I find more information? And last question, what can I do to fix this noise?

Car: Skoda Octavia Combi 1.6 TDI (2011 model)

My wheel/suspension setup is all factory fitted and consists of:

- Pegasus 17'' rims

- tires with a mere 20k km on them and still looking new (threadwear ok and even, and tire pressure checked every week)

- sport package suspension

Thank you all briskodians!

Edited 8 February, 201214 yr by JoaoP

I'd agree that this sounds very much like a tyre issue.

If you can say that the noise appears to be coming from one corner, put the spare on that corner and see if the noise goes away. If it does, then you need to inspect that tyre very carefully. You may find that it is sufficiently out of round to have reached one of the wear bars although the rest of the tyre is fine for depth.

Otherwise look very carefully at the individual tread blocks to see if they have "saw-toothed", that is are deeper at one end of the blocks than the other. If they have, and you have non-directional or asymetric tyres, try putting the tyres on the opposite side of the car, and the noise should stop. Do not do this if you have directional tyres, with markings reading "left" and "right" on the sidewalls.

1/ What tyres?

2/ Where are you? (I suspect not the UK)

Have the wheel off and check to see is the disk pad wear is significanty uneven between different sides of the disk and across the pads. If it is suspect bearing wear.

And/or with the wheel back on, the car jacked at the front and someone holding the steering wheel in a fixed position, grip the tyre top and bottom and waggle it against the resistance to see if there is any play. Repeat with hands at the three 0'clock and nine 0'clock positions

Nick

Have the wheel off and check to see is the disk pad wear is significanty uneven between different sides of the disk and across the pads. If it is suspect bearing wear.

And/or with the wheel back on, the car jacked at the front and someone holding the steering wheel in a fixed position, grip the tyre top and bottom and waggle it against the resistance to see if there is any play. Repeat with hands at the three 0'clock and nine 0'clock positions

Nick

I've been told by a time-served mechanic (and he was proved right about it not being bearings in my case; it was actually a stone under one of the dush shields on the discs) that VAG wheel bearings don't make a noise, and don't really respond to the rock test you detail.

I've been told by a time-served mechanic (and he was proved right about it not being bearings in my case; it was actually a stone under one of the dush shields on the discs) that VAG wheel bearings don't make a noise, and don't really respond to the rock test you detail.

Of course they don't . . . especially when it involves a warranty claim.

Answer to that assertion is why ? How do the SKF bearings supplied to VAG differ from those supplied to other manufacturers ?

Nick

Of course they don't . . . especially when it involves a warranty claim.

Answer to that assertion is why ? How do the SKF bearings supplied to VAG differ from those supplied to other manufacturers ?

Nick

Warranty didn't apply in my case, and a new bearing would have cost more than half an hour's labour. I forget the wording, but basically I was told that they weren't normal SKF taper rollers.

Thank you all for your input.

My tires are: Bidgestone Potenza 225/45 R17

Don't know it it matters but I am not from the UK.

One thing I forgot to mention, and might be important: - yesterday while doing a dyno run the car had the tendency to move to the right.

Edited 8 February, 201214 yr by JoaoP

That tyre's not obviously saw-toothed, but on the Octy 2 you can get saw-toothing on the rears. When you do, it is normally cause by the fully adjustable rear suspension geometry being mis-set. With a car this new, that's a real possibility if it wasn't PDIed properly.

As to the pulling to the right, that's called "torque steer" and most FWD cars do it to some extent (OK, Hondas go left because that's the side with the long driveshaft). You'd notice it more on a rolling road because the engine revs rise faster than they usually will when you're driving.

That tyre's not obviously saw-toothed, but on the Octy 2 you can get saw-toothing on the rears. When you do, it is normally cause by the fully adjustable rear suspension geometry being mis-set. With a car this new, that's a real possibility if it wasn't PDIed properly.

As to the pulling to the right, that's called "torque steer" and most FWD cars do it to some extent (OK, Hondas go left because that's the side with the long driveshaft). You'd notice it more on a rolling road because the engine revs rise faster than they usually will when you're driving.

That was a very good answer! Thanks!

I will take a pic of the rear tires just to see if you can help me diagnose this problem.

I have 2 questions, related to your answer:

1. What do you mean by "PDIed"?

2. The mis-set of the fully adjustable rear suspension geometry can be diagnosed/proved/verified how? I need to make sure so that I can tell the dealer to correct the problem.

That was a very good answer! Thanks!

I will take a pic of the rear tires just to see if you can help me diagnose this problem.

I have 2 questions, related to your answer:

1. What do you mean by "PDIed"?

2. The mis-set of the fully adjustable rear suspension geometry can be diagnosed/proved/verified how? I need to make sure so that I can tell the dealer to correct the problem.

Is PDI = Pre Delivery Inspection?

Is the engine undertray secure? Loose undertray can cause noise related to speed as you describe

Is the engine undertray secure? Loose undertray can cause noise related to speed as you describe

I'm not 100% sure, but the sound might be coming from the rear.

Is PDI = Pre Delivery Inspection?

Yes.

I'm not 100% sure, but the sound might be coming from the rear.

That suggests the rear tyre sawtoothing I was talking about might be the case.

There's no DIY method of checking rear suspension geometry that's any more effective than looking for uneven tyre wear though.

Yes.

That suggests the rear tyre sawtoothing I was talking about might be the case.

There's no DIY method of checking rear suspension geometry that's any more effective than looking for uneven tyre wear though.

If there is no method to test the suspension geometry set-up why do you say they did a bad PDI?

Also, how can someone setup the geometry if there is no method to know if it is correctly adjusted?