Whirr....Whirr....Whirr..... above cetain speed

[unclehrvatska]

Hi all,

After some advice about a strange whirring noise that is very consistent at certain speeds.

Car is a Leon 1.6diesel 2010. At idle and normal speeds it sounds fine. Starting at 66mph going up to 75mph, it starts to make a WHIRR WHIRR WHIRR noise.
As it gets faster in this range the whirring also gets faster. Then above that speed, it stops making the noise.

Garage had no idea and an inspection showed nothing unusual. Any ideas?

[cuprabob]

Rear tyres are prone to odd wear patterns (treadstepping / sawtooth) that cause such noises at certain speeds.

[unclehrvatska]

Interesting and thanks for the reply. I did get a new front tyre at the last service.

On closer inspection just now I noticed (this is a new car for me) one rear tyre is labelled Pirelli P7 and the other Pirelli P7 Cinturato. Googling shows they have slight differences, but I wonder if this mismatch is causing it, and should I be concerned?

[GreenV8S]

unclehrvatska said:

I did get a new front tyre at the last service.

Just the one new tyre? That's unusual.

[unclehrvatska]

Indeed - as I said it's new to me so I have no idea how much tyre swapping the previous owner did......

[GreenV8S]

Could be the tyres, but in my experience tyre noise is typically quite high frequency. If the noise is more of a low drone/rumble, it might be something resonating when the road input hits its resonant frequency.

Edited by GreenV8S on Friday 22 September 18:05

[stevieturbo]

Above 70mph you say.....any blue lights accompany it ?

[unclehrvatska]

Well I took it to 75 to test out. Allowing for speedo calibration error of 5% I reckon I was going about 2% over the limit.
I would wager my house and both my pedigree corgis you have been 2% over the speed limit.