Jim G, if you are driving often in weather that is hovering around 0 degrees C, a good shopping technique is to buy a tire that is 4 seasons of course, and has a LOW treadwear factor. The lower the number, the greater the sticking to the road in colder conditions.
The lowest treadwear rating is in winter tires, where there isn't an obligation to publish it. In the Spring I have used them to corner a bit faster than usual, especially if there is a tailgater following me.

 

If there is a fault with one (or more) height sensors, yes it will as, mentioned, default to a firm ride. But you will get a mention also on the "Message Centre" advising the fault. Autel should be able to tell you which wheel has the bad sensor.

 

I have fully functional fault-free xkr (07-09) suspension and it is quite a firm ride with the 20" wheels , however when I switch over to my spare set being 18" the ride quality is vastly improved due to the large profile front and rear.

Would you consider a large profile on your current wheels or even dropping back to 19"

Has any increased the profile on their 20s front & rear and if so was there any clearance issues?

 

Precisely right. I use the 20s for summer only. The All seasons ( and I think the winters) are on 19s.
The rears on my 20s are slightly larger. Giving the effect of a larger profile. But not so large to greatly affect the scrub angle.

I tried oversizing the front once. It didn’t work out for me. So after the weekend I switched them back to the spec’d size.

 

Jim, Clubairth addressed your SDD question, and Sean pointed out that the Autel AP200 (must have the JLR download!!!) supports suspension analysis.

I've used SDD for years. Yes, it has a lot of very useful detail, but it has a Neolithic user interface and a very steep learning curve. If you decide to use it, you'll have a fair amount of research to dig through. That's why some of us use the AP200 -- cheap, has a lot of good basic tools and some nice things like seat re-calibrate and CATS data access to confirm suspension ops. Toss the AP200 BT dongle in the glove compartment and it's right there when you need it.

SDD, OTOH, needs a laptop and special cable to operate. So, the AP200 is my first go-to, and SDD if I need to. **This not a wholesale pitch of the AP200. For more money you can get a lot more functionality with more complex analysis tools.** But I haven't seen better for the $70 on our cars.

Good luck, and it's with the effort to improve your DIY skills that makes the biggest $$ difference with a XK. Particularly with the dealers, walking in wide-eyed with "Please fix my car" will severely bruise your wallet. The guy who owned mine before me was charged (at my best estimate) $6K across 3 visits for a fuel pump, fuel filter, and two injectors that didn't fix his lean fuel trim problem. He got frustrated and sold it cheap. It was a bad 50 cent oring on a third injector, that I found after I bought the car, that was his problem...and not on the bank that was diagnosed by the dealer.

This forum has a massive set of very clear documentation available on our cars. (Though I was feeling masochistic and reading the repair manual on the ZF transmission yesterday and holy crap is that thing complicated.....)

Keep asking and you'll get help.

 

Agree with panthera999 and I also have the AP200 unit. Mainly because it will turn the service indicator off (On my 2014 XJR) and as posted above it's WAY easier to use than firing up SDD!
Still surprised something so cheap will do so much. It's a very good value.
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Me and my buddies WAY back in the 1900s used old used cheap snow tires for drag racing since we were poor teenagers. They sure did get gooey after a short burnout.

 

Cee Jay’s burnout car, from back then:

 

Close, but I'm not quite THAT old. Besides, can't beat a blown Hemi on spray.

 

Hmmm, our definitions of ‘poor teenager’ are a bit different!

 

Is this going to open the black vs hypersilver wheel debate all over again HAHAHa