It is easy to check the tread depth of your tyres for yourself, without the need for a fancy depth gauge. Just a twenty pence piece is all you need!
There’s a rim around the edge of the 20p coin that is about 2mm wide. Stick the edge of the coin inside the tyre tread and if you can’t see the raised rim you’ve more than 2mm of tread.
If you can see the raised rim then you may need to have tyres replaced.