Hi Team. I have a new to me XK Conv 2006 and it has Khumo Tyres fitted all round. On the rear are 295x30x20inch and I have a major problem when driving through rough corners that the rear end will jump or tramp and loose contact with the road causing the car to be unstable.
I tried 40 psi which increased the problem and now down to a cold temp of 33 PSI on the rear and 32 PSI on the front.
With the Jag suspension is there any way to reset it or any suggestions would be appreciated.
On the highway at speed it runs like a dream. Oh the car only has 52000 Km on the clock and the tyres are near new.

 

You didn't indicate if these are all season or summer compound tires, but more than likely the Khumos have a hard compound. Harder compounds won't stick as well but tend to wear better.
I think 295 is a larger diameter than recomended but others may have better input on the accuracy of that.

 

Hi. They are high speed tyres. ZR. We don't need winter tyres here in Australia.

 

Kumho tyres might not be the best tyres money can buy but they are usually respectable and should not exhibit major problems unless you are on the absolute ragged edge. However, make sure that they are not old and hard or damaged.

More likely is something in the suspension that is out of alignment, worn, or damaged. I would first make sure that all suspension components are sound and alignment is correct. Incorrect alignment, especially at the back can cause odd/dangerous handing. Is the tyre wear really very even? You can read a lot about the condition of a car by looking very closely at how the tyres are wearing. If they are not wearing evenly, don't rotate them until someone has worked out what is not right as you will confuse the picture.