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I don't drive, so have no knowledge of different types of vehicle tyre beyond knowing about winter tyres/run flats etc.
I've noticed when out on the road bike that some vehicles coming up begin me are really noisy from the tyres, puts the willies up me TBH & it seems to happen regardless of the type of road surface.
All tyres come with a Db rating for noise.... some are quiet, some are loud.
Never knew that! I was wondering if I was hearing run flat tyres as I imagine them to be constructed differently to normal tyres.
Something like an X5 will also sound very different to something like a Ka. Wider, lower profile tyres, supporting more weight, tend to sound louder and closer when they approach.
Run flats typically have a central rubber support in them so if the main chamber deflates there is a support the wheel can sit on for a period of time or they have extra supportive side walls.
Under normal operation they shouldn't sound any different to normal tyres. Will jsut be the type of tyre the owner has chosen. More noise is probably from tyres with a bigger contact surface.
You are right OP, some tyres are bloody loud others seem whisperingly quiet these days...
IIRC an EU directive a few years ago decreed that all manufacturers now have to supply information on a few key metrics for any tyre to help the customer when choosing:
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I also think its more noticeable now because many modern cars are so very quiet when running.
As an aside, I was followed through some roadworks yesterday by a bright red Jaguar F-type - now that sounded lovely 😀
all season and winter tires also create more noise (part of the mechanism they create more grip by - that is the tread pattern and compound)
and with the major motoring groups mantra being if you can only have one set of tires for year round use in the uk use all seasons or winters - many folk are rolling on all seasons or winters all year round.
Having just been through the process of getting new tyres, the Db rating thing is a bit of a waste of time. There's only about 3Db between upper limits allowed and best in class. Differences in road surface will have a much greater effect!
I went for mid-range tyres to replace worn expensive ones, so went from some rated 71Db to 73 I think. The newer ones are much quieter! (Probably as the old ones were well worn)
There is a significant effect from the tyre choice & many different types of tyre noise.
They are generated at a wide range of frequencies, excited by certain surface types (&/or obstacles) and road speeds
The labeling measurement has some relevance but is just a small part of a big picture
Try riding a fat bike on tarmac, you can't hear anything apart from the buzz of your own tyres.
There's only about 3Db between upper limits allowed and best in class
3 Db is something like double the intensity from memory. So not that insignificant. perceived loudness does increase as much but if bodywork is channelling the sound it can make a big difference.
I'm not sure how they are measured - ie if it's standardised for width and road surface - ie maybe it's done on a roller of set width but lots of variables that can also affect it, including run flat construction.
It may be co-incidence but I seem to notice Vauxhall Insignia's (IIRC) on the road a lot more because of the tyre noise. The suspension and chassis set up will also contribute to the resonance from road tyre as well as the surface.