One of the tougher things to figure out on this forum is whether the stereotype applies. I can't think of a batter example than tire selection.

Outside observation from three steps back:

There are probably a lot more people on this forum that will go after trying to squeeze even more performance out of a car that has pretty good stock performance. This is performance as defined by going faster, sounding like a high performace car, etc.

The following advice is not for them as you can compromise a little on quiet and ride to achieve performance as defined above. The following is thinking about the mind set of a Jag engineer, the target audience for a new car and performance as defined by that target new owner:

Jaguar engineers do a very good job on a some things. One of them is providing a great, limosine quality ride, particularly in the sedan series cars. One of the critical elements of suspension design is understanding the "unsprung weight" or total mass of the moving parts of the wheel and suspension system, the spring rate (stiffness) and damping factor (shock absorbers).

If you change the size of tires dramatically beyond the engineers calculations trying to do a better job of what Jaguar and Rolls Royce do better than any make in the world when the quiet, stable ride provides the target audience for them to sell new cars (their bread and butter), you will start to diminish the otimimum calculations from the design engineer. They would have no issues with selection of tires, related expense and marketing departments, etc. in making the tire recommendations.

The one place where there may be a different tire selection for you is the target audience for the "R" series cars would usually favor cornering or high speed performance over quiet ride if there was a difference that would make a tire appear on recommended list for one car but not the other. This is where you might deviate from the target audience for your car.

I would look at the mass (weight) range of the recommended tires and keep it in mind if I changed tire sizes. If you find a tire that is recommended by Jag for non "R" version but not on list for "R" version it is likely a handling over ride choice. I think both types of XJ's are electronically limited to same top speed.

Armed with that information I would talk to a Rolls Royce dealer. They are often dealing with owner's with this set of priorities and deal with tires more than other makes as owners are less likely to shop for tires directly.

I would go with recommendation of rolls dealer for brand in size not exceeding that sepecifed by Jag. If you exceed recommended size, double check on mass (weight) of tire, try not to fudge by more than 10%.

As well as side wall stiffness and pressure that transmits the noise into the cabin, the tread pattern itself has a lot more to do with the actual noise origination factor. We did a lot of freeway noise control testing at an acoustical consulting firm I worked for and the bulk of noise is not from exhaust or intake but the making and breaking of tread contact with the road. The grooves that allow water to shed out the sides and provide better corner control compromise noise over "old man style" tread with continuous pattern around circumference that resemble bias ply tires. Best over the top examlple, roll down window next to caddilac or rolls, then next to jacked up truck with off road tires.

Good Luck on your selection!

Steven (1avguy)

 

How are you liking these so far KruBruder? Any updates?

 

When I purchased my Vanden Plas almost a year ago the rumbling from the Kumho tires has about driven me out of the car. They were installed when I got it. The size is 255/40ZR19 KUMHO ECSTA SPT. Does anyone have experience with these tires and what can I replace them with that will be quiet? I don't drive 120 mph so I don't need competition type tires. Thanks!

 

I replaced the very noisy (but very sticky)Pirelli P-Zero Asimmetricos on my 2005 Super V8 with some Toyo Proxes T1Rs and have been very happy with the ride comfort and noise level.

I don't think you will win any slalom course races with these tires (Car and Driver hated them) but if you are like me and spend most of your driving time going in straight lines the reduced noise might be worth it. I think if I had an XJR with the shorter wheelbase and tighter suspension I might have opted for something a little more aggressive.

 

When I first got my car it had 2 new Falkens in the front and 2 Pirelli 50%Asimmetricis in the rear. In the course of normal tire rotation, the Pirellis ended up on the front and the noise went up a lot. The car performs marginally better with the Pirellis in front but I do look foward to getting them to the back again.
The Pirellis, when cold, cause a slight steering wheel shake that goes away after 3 to 5 miles. Go figure.

 

KruBruder, how do you like these tires?
I am getting much closer to buying them, but I need some additional push to encourage me to buy the oversized tires with extra smush...
I have been waiting for any update, I hope all is well with you.
Perhaps I will PM you.

 

On my 2008 3.0 Soverign I use Pirelli P Zero 255/19 on the front as are the standard fit, with Pirelli 275/40/19 on the back. Using chrome versions of the same rims as in your pic. it has corrected my speedo reading which was showing approx 5 mph faster than when checked using a proper stand alone sat nav from my old XJ8. P.S. The tyres are not at all noisy and give a good grip.

 

I just got some Verde Axis V99 wheels in 19x8.5 and 19x9.5. Above someone mentioned they had run 275/40's on front. is this correct?