Debris inside tyre

[XG332]

I was driving home last night on the M40 and i noticed my car was making a loud metallic scratching sound. So i pulled off at the next junction and had a look.
I checked the wheels were tight, bearings, pads and discs for heat. But nothing.
So i limped home the back way.

I have taken the caliper, pads, disc ect off this morning and found nothing.
The only fault i have found is that it sounds like there is debris inside the tyre and rim that sound metallic.


Would this cause the noise?
I needed a new tyre anyhow, so am changing it.

oli