Sorry about posting another thead about tyres but having searched I am struggling to find an exact answer to my problem!
I have had my X5 a couple of months and the rear tyres had just about 2mm left so decided to swap them. Having looked at options and as I dont do many miles a year I have gone for the Pirelli PZeros 315 35 20 (rather than the more expensive star marked tyres). The fronts have a set of Goldway tyres (never heard of these) 275 40 20 with about 5mm on so I thought these would be ok for a while and then I could look at replacing these for Pirellis in due course.
Now since changing them last weekend the car has gone mad! On the Saturday I had them done other than the odd wobble it wasnt too bad, but over the next few days driving the car has been terrible. It shifts gears at wrong times, theres a slight grinding sound and it feels like at times I am driving on tram tracks

I have since read about having to replace all four at one time (and potential damage to the transmission and transfer box- hopefully this hasnt happened) so I am thinking of putting two new ones on the front to see if this corrects it. For a couple of new Pirellis its looking at about 450 but I am a bit loathed to do this in case it doesnt fix the issue. A friend of mine can get me a full set of 4 accelera iota for £300 fitted so I am thinking of giving this a try to see if it solves the issue. If so I can then get the Pirellis and sell the acceleras on ebay and it get me a bit of cash back...
Would be interesting to hear other peoples thoughts before I go ahead with this, thanks