Mixing tyre types

[roz84]

I have a ssangyong rexton which is fitted with BF Goodrich AT tyres all round - the front ones are virtually new, the rears are near the limit and I have the MOT coming up and some other bits need doing on the car.

I've seen other AT tyres at nearly half the price of the BFGs, would it hurt to fit a set?

[roz84]

I suppose what I'm actually asking is will it damage the car to fit a cheaper set? I know that some cars have to have the same fitted all round - these would be same type/tread pattern etc just a different make!