Whilst polishing my exhaust tips at the weekend (an oddly gratifying car cleaning task, I fully recommend it) I got a decent view of the inside edge of my rear tyres. Having worn through the inside edges of the tyres on my previous car, I am careful to check for uneven wear and probably have a feel across the tread on fronts and rears every two weeks or so. Clearly with these wide tyres I am not feeling far enough on the rears! Here is a bad pic, but you can see that there is no tread left on the inside inch or so.

There is enough tread on the other rear tyre for another couple of thousand miles, so it is a bit galling to have to fork out for new rears now. The tread is so low I daren't even do the celebratory burn out I was planning before the new ones are fitted in the next couple of days. i am switching from the OE Dunlops to Michelin PSS. I am leaving the Dunlops on the front as they are hardly worn at all. I believe my rears have lasted for about 7500 miles - yikes! I have been giving the rears a bit of work to do, I must admit. I had put down the recent increased playfulness of the rear end to my own increased confidence, but I guess it was because I was running on semi-slicks...

So, an alignment is also planned for next week of course. I encourage you all to check your tyres for uneven wear, and save yourself a few hundred dollars...

 

That looks pretty bad.....Is the camber adjustable in the rear?

Uneven wear can also be caused by not having high enough tire pressure in the tires. I personally recommend tire rotation every 5000-7500 miles.

 

It is difficult to rotate tyres on an XFR though - unidirectional and different sizes front to rear. Plus, with 500hp on tap, making them last long enough to bother with rotation is a challenge!

But yes, it is bad, I was a bit surprised and annoyed with myself... I am assuming that the camber is adjustable - the other side is fine and wearing evenly (if anyone wants a 75% worn Dunlop, let me know in the next day or so...)

 

A high power car (500 hp) with traction control and an enthusiastic driver who likes to use it. Sounds like a recipe for rapid rear tyre wear to me !! Do also remember that Jaguar and other high performance cars no longer use limited slip diffs, the rear brakes are used to stop wheels spinning.

Having said all that, clearly there looks to be an alignment problem. Almost all of the settings are variable front and rear

Camber
Caster
Two-in

ANd others I can't think of, but camber seems the problem in this case

 

Right rear normally wears faster than the left rear even for independent suspension.

Inside wear would be normal as the rear suspension squats under acceleration which normally induces more negative camber.

It is difficult to be definitive, especially from just a photograph but that tire wear looks within the range of normal given the implication that to wear them out in 7,500 miles implies you enjoy aggressive launches. Also, tight right handers are more common in North America so the inside drive wheel tends to wear faster. Depending on the suspension geometry it is also normal for that inside wheel to droop into negative camber relative to the road due to effects of body roll. Remember that camber effects are meaningful only relative to road surface which is why camber is variable through the range of suspension travel. If the body didn't roll then camber could be a fixed amount.

UK drivers wear out tires faster than we do as they have very bendy roads. Even their freeways are all curves. There have been a lot of posts by UK drivers complaining about short tire life especially from Pirelli tires. Dunlops seem to last a bit longer.

The newest Michelin Super Sport is getting rave reviews for grip and better tread life.

I'd have the alignment checked but I bet it is within spec.

 

Darlo, I had the dealership do an alignment on my 2011 Premium just before the 1 year/12,000 free adjustment service was going to expire. Surprisingly the fronts were spot on spec, however the rears had a substantial amount of negative camber on both sides....came that way from the factory so its not surprising on you are experiencing the same.

 

Thanks for the interesting perspectives guys. The difference in wear is so marked between left and right that I can't believe it will be within spec, but I will be sure to ask for before/after measurements. I am hoping that my alignment will be free. Given the recently found early warranty start date I am outside of 12 months but inside 12k miles. I asked for the alignment to be done months ago but the dealer's machine was broken so I took a rain check on that.

It is difficult to tell what the life of these tyres has been. The history of my car has involved some track work I believe, so it is possible that these tyres have been on track. They were about half worn when I took delivery 4k miles ago, but the wear looked even at that stage. The fronts have barely worn at all.

Will report on the Michelins when I get them bedded in a bit.

 

Fraser,
The XF S/C and XFR not only have LSD, but electronically controlled one (E-DIFF)with an electric motor attached to the diff,which varies the degree of slip of the clutches inside the diff. Our cars have it for 2 years already. BMW finally will come with the same set up on the 2013 M5
Cheers

 

Well, there's something I didn't know. So it would seem LSDs are coming back, and not before time, I reckon, it has always seemed stupid relying on the brakes to cure rear wheel spin. Actually, I have never had a car with an LSD. They were once very common on Jaguars, but my XJ6 Series 3 never had one, it was an option, or standard on the V12s I think.

 

I think my 09 XF S/C has a different dif then the 2010+ XF and XFR? Now matter what I only get 1 wheel to spin. This is very annoying at times especially when turning. I will say this always keeps the car from sliding out of control and keeps the car going the intended direction. There is no way you could drift my model ever with this 1 wheel wonder. You can see what I mean if you watch the Top Gear episodes on youtube when they reviewed the 09 S/C and the 10 XFR.
So far my rear tire wear looks even and I have 28k miles. I have been also keeping a close eye on the inside wear as my AMG squats on take off always and has the wearing issue on the inside.

 

On the contrary, jaguar was never a fan of LSD for their road cars for good reasons. The electronic slip control effected by use of the ABS system gives superior traction in ordinary road driving. Indeed, mechanically speaking there is no difference in effect on traction between the two types until you wish to spin both rear wheels. The electronic type will not permit this but the mechanical type, even if electronically modulated, will.

For track driving a mechanical type LSD is superior. For road driving it is not. An LSD causes excessive understeer especially on turn in unless you intentionally put the boot in to balance the expected understeer with a little excess rear drive. On the street it is exceptionally rare to be in a position to benefit from this technique. Unless you do then the mechanical LSD is just a boat anchor. The ABS based fully electronic systems have no weight penalty, prevent unnecessary wheelspin and do not induce understeer.

The electronically moderated mechanical LSD is the only one to bother getting nowadays and only for track work or stunting!

Oh and BTW, you should have no trouble drifting a car with no LSD with the horsepower of the SC. you need to select DSC off by pressing that button for 11 seconds until th message DSC OFF appears. Then give 'er the boot and twist the wheel a tad and off you go sideways. Heck, I can do that in my base XF if the road is cold or wet.

 

Mine must be broke?

Jaguar XFR review - Top Gear - BBC - YouTube Start at 2:30 and 3:30

Jaguar XF Top Gear - YouTube start at 2:40

Cadillac CTS-V vs Jag XFR - Drag Race - YouTube Look at 28 seconds. I have tried this with only 1 wheel,never both wheels. I must say my car is perfect for when you want to always stay in control and fully stable in the intended direction. But for a lil fun it is everything but that. The E-Diff must be totally in control here?

 

It is possible to smoke both rear tires with an open diff. The open diff doesn't direct 100% of the torque to the spinning wheel. Technically, the open diff delivers up to twice the torque to one wheel as it does to the other wheel. With good traction surface you can spin both wheels if you have enough torque at the drive wheels. As traction grip goes down so does the likelihood of spinning both drive wheels. Most of us experience wheelspin at one wheel when traction grip is very low, the diff is still delivering one third of the torque to the non spinning wheel but on very poor surfaces this isn't enough to move the car. This is how Torsen diffs work, internal gear friction delivers a Pre set torque ratio independent of surface grip unless surface grip reaches zero, I.e. one wheel off the ground. This is how Audi Quattro drive works, the center diff is a Torsen.

 

Well, regardless of what the diff is doing, the chances of spinning up the rears while wearing Michelin PSS appears to be much less than when wearing Dunlop. Despite only driving a few miles on them, they do appear to be grippier. No notable change in road noise - less if anything.

I hung on to the "good" Dunlop that came off the car - that appears to have worn more heavily in the centre than the edges, although only a small amount. Pressures have never been over during my tenure at least... Probably has a couple k miles of careful driving left on it, but it isn't much use to me.

 

High speed driving can wear the centers of the tread even at correct pressures. Heat raises the pressure and centrifugal force distorts the tire causing wear at the center. Your tread wear pattern seems within the range of normal. Did the alignment confirm the suspension is not the cause?

All reports about the Michlin SS are excellent. I think Porsche has approved of it as OEM.

 

Makes sense - thanks. Yes, I have done some high speed driving! Alignment is booked for next Tuesday, so will report back after that.

 

I can't wait to try a set of those Michlin SS's out.
I did go out and try every senario while spinning the rear tires. Not once "Traction off completely" was I able to roast both tires. It was only 1 or the other. Most of the time it was the driver tire spinning. So I give up on this tire spinning subject til I get an XFR.

Regarding tire wear : I am not sure if these are the OEM tires that came on my car but I am Perfect thread wear for now on my 255/35/R20 97Y Dunlop SP Sport Maxx tires. Are these the ones that come on the 09 S/C?
I truly expect to have bad inner tire wear like the above thread starter since I am always on the gas a bit more than othersfrom a stop.Thus the car squating all the time to cause this uneven inner tire wear.But so far I am lucky.

 

Are you talking tire smoking or tire slipping? I am not sure how you are sure only one rear wheel is slipping. Maximum acceleration is obtained with no more than 10% wheel slip which will not smoke a street tire. Once the smoke appears you are no longer accelerating as quickly as you could. Drag racers slip their tires a bit more for other reasons. A burn out is only to heat the tires which is generally not useful for most street tires.

 

I speak of simply sitting still and roasting both tires like the 3rd link I posted above to heat the tires.

 

Unlikely you can do this with an open diff. Wondering why anyone would want to. ....

You do need a mechanical LSD to do this. I'd be interested to know which modl the Aussies tested, supercharged but did it have the LSD from the XFR or not? You can see both tires light up briefly as the weight transfers from one wheel to the other during the transitions. It doesn't look like an LSD but the commentary refers to the desirability of a "tighter" diff which on,y makes sense in the context of an LSD. Jaguar only fitted the clever electronically adjusted LSD which is looser than the purely mechanical LSD to allow a wider range of slip options, continuously variable in fact.

The SC does not have the LSD.