I do not know but I presume that this means the pads have worn the discs thinner than the rim of the dics, which may also be thicker due to rust.

I presume in the worst case new discs? is this a cheap fix? sureley?

I am contermplating buying a 2008 Ford Focus estate from a car supermarket. The RAC report states that the front discs are rimmed. What does this mean and is it an expensive repair?

Need not be, but phone one of the chains and get a quote for 2 new discs and pads, and allow for that in your calculations, and if it has done a fair few miles allow for a 3 year sevrice, checking the brake fluid too, and an mot. Still worth it after all this? tell us the model and mileage and you can also check the price on websites, I also assume that you won't get a warranty worth the name on it, so be prepared to rely on the sale of goods act. If in doubt, go to a ford dealer and pay a bit more.

Good luck and happy motoring.

front discs are rimmed. What does this mean and is it an expensive repair?

No. Jack up car, remove wheel, handbrake on firmly, chock other wheels, start engine, engage first gear GENTLY, apply rapidly rotating carborundum wheel to 'rim'.

If you've let it get really bad you might have to take it off, chip away rust on the inner bit [which can make it sort of swell up] and then smooth it off. Then you'll need new brake pads unless they are are still fat enough to smooth off too. Then you'll need to bed them in by regular gentle braking otherwise it won't pass the MoT test which is REALLY stringent on brakes these days.

My discs last at least 100,000m - record was about 190,000 on our old Passat [admittedly lots of dual carriageway with not much braking].

'you need new brakes/pads, squire' has always been a bit of a racket - there is a lot of rubbish talked about discs being 'disposable items' - they're heavy solid steel!