Another tyre question - replacing the rears only???

[Graeme]

The winter tyres are on and the wheels with summer tyres are off.  However, after 24000 miles the rears (Continental 285x45x19 111V RF) are worn out and need to be replaced for next year.  The fronts (Continental 255x50x19 111V RF) are only part worn with 4-5mm tread left. I have another pair of part worn fronts also with 4-5mm tread left that I could use so that in two summers time I'll surely need a full set!  By then the car (made in 2007) will be very long in the tooth!!

If I only replace the rears is the risk that the difference in circumference between front and back will damage the transmission too great to take?  Two new continentals for the rears are about £360 plus fitting. I can get new Goodyear Eagle F1 Asymmetric 2 all round for about £620 plus fitting. I probably know the best answer but what advice do folks have?

[X5Sport]

The E70 is supposed to be more 'tolerant' however it might end up being a try it, see if there are any odd noises, vibrations, grinding sound etc and keep an eye on it and change the other set once they get to about 3mm (which is a common recommendation these days).

It's going to be one of those 'suck it and see' occasions or you just change them all now.

Both of my 'X' cars have always worn evenly across all 4 wheels so I have always had to change complete sets..