Hi everyone!

Hope someone can help diagnose this for me, but I will take it back to the dealership once I get the chance.

Car is the 997.2 Carrera 3.6L PDK on 19" Carrera S II wheels.

Tyres are Advan AD08 all round, 295x30R19 rear, 235x35R19 front.

They generally made a little more noise than the Michelins, but lately they've taken on a hum & roar that at 35 to 40 mph makes a god awful resonating hum with a beat frequency of around 2-3 Hz. The resonating frequency of this gently vibrates the chassis and I can feel it through the dead-pedal footrest. (no clutch pedal, PDK). The resonance will spike in amplitude if I cruise at those speeds, and lift-off; i.e., coast in-gear. The resonance disappears and the sound is normal again after 42-45 mph and above.

I had a puncture on the rear right (my car is RHD, so driver's rear) but that was fixed properly with the tire dismounted and plugged through-and-through. However, the noise only started becoming an issue 3,500 mi afterwards. I can't seem to pinpoint which corner the sound is coming from, it's a resonance that just immerses you!

I have thought that it could be a balancing problem, but my gut feeling is that it's more than that.

I would also like to qualify that I have used steel side-walled semi-slicks so I know what REAL tire roar sounds like; this sounds almost like that, except that this resonance occurs between the aforementioned speeds. My previous use of semi-slicks on one of my old track cars exhibited resonance only when slowing down from 20- 10mph to rest.

Here are my 'problem caused' suspects:

1. Tire imbalance
2. Tire repair failure
3. Wheel bearing failure

I am thinking it could also be just that the ADVAN AD08 are just very noisy as the sound is dramatically reduced (albeit the resonance still there) when I cruise on different coarse / grit paved roads. But the 'coasting' noise spiking is making me awfully suspicious...

 

Hi there


First question how do the AD08's handle compared to your Michelin PS2's you had on previously?

When I had AD08's on my EVO they were indeed a noisy tyres, as they have rock hard sidewalls and are a DE/track type tyre so they give far more road noise than any Michelin so I'd say its pretty normal.

 

1st, 3.6 997.2, dont you mean 3.8
2nd, different noises on different roads. Try smooth even road and if its gone then theres no trouble, just different roads noises.
3rd, tire pressure, have 38 front and 40 rear at hot operating temp and see if it changes

 

1st- it's indeed 3.6, the 3.8 is for the Carrera S, mine is the base model.

2nd- it's heard on all road surfaces, even on smooth.

My tire pressures are sitting on 37 front, 44 rear COLD. I will try your recommendation.

On listening to it again yesterday, it isn't actually so bad. I now rule out any real mechanical problem and limit it to an imbalance, at worst.

I do remember now that with sticky & noisy tires, they tend to get noisier as they wear. I.e, there is less tread depth and less squirm resulting in more noise from a stiff tread block.

Also, to the first reply, these tires are awesome and around town definitely has higher grip levels and performance than the stock Michelins. However I need to put then to the test on a track day to really say how much better they are. Looks great with the shallow rear flanks of the 997 exposing lots of that aggressive rear tire tread to the rear view.

Thanks for the tips.