I am replacing the Rear Dunlaps on my XKR. The old tires that came off were thru the rubber and into the belts only on the inside of the tires...one side a little worse than the other. In fact there is maybe even an 1/8 inch tread on the outside while the inside tread looks as in it is wearing up and around onto the side wall (don't ask me how as I did not see anything that appeared to be rubbing it). The bottom line is that the rears are definitely wearing much faster on the inside track. My concern is that the rear is not adjusted correctly and is going to wear my new tires excessively on the inside as well. I had the dealer check and adjust alignment (mostly due to steering wheel being slightly off center) for all four wheels as I knew I would be putting on new tires shortly (this was about 4 thousand miles ago). So the question is: Does anyone else notice this same wear pattern on their tires?...have I been bamboozled again by a dealer that only checked the front and just completely ignored the rears?...does everyone (anyone) see this wear pattern?...
Good Day...

 

Now your talking the wear that myself (and most xk8/r) owners are used to...however, we've got the older models. Hard to believe your 07 is having problems in the same area.

In our case, the time of having such a heavy engine on the front springs wears the coils, disfigures the upper mounts, and we have no camber adjustment up front to accommodate. An eccentric bolt was added by jaguar to give it a little assistance, but we're stuck with the camber we have. Replacing upper mounts and adding that ebolt gave me back almost an inch of ride height, and helped bring my camber into spec on one side, and just out of spec on the other. Still, i get some inner tire wear as a result.

On my rears, my original camber was out of spec. Jag now makes a shim kit for it, and after install, got my numbers back to respectable range. Now, i only get increased center tread wear, which is typical for these cars I am told. For you to get excessive inner tread wear is odd.

Get new tires and watch the tread depths. If you see excessive on the rear again on the inside, take it to the dealer for another alignment, and perhaps a fix.

 

As I recall the rears have a trailing link that is adjustable but I have no idea whether this would eliminate this peculiar wear. I did notice before the dealer aligment that the wear did seem to be more on the inside on the rears...but nothing like what they were when I replaced them (I am talking wayyyyy into the belts...gulp)...I was looking only at the outside of the tire and did not even notice the inside wear (I would suggest everyone check...they are really deep tires and it is the worst only on the inside inch or two...and I am thinking I was lucky as it was). I also just completed a 4,000 mile road trip which may have aggravated the uneven wear in that there was little or no cornering involved...but still....I would think that would just help even up the wear.

 

I wish I knew more about the suspension differences in our model years drag.

 

In case anyone is wondering these are the 20 inch sentas. I had Michelin PS2 on the front for a while with the original Dunlaps on the back (the ones I just replaced that had bad inside wear). The new tires I put all around are Michelin PS2 A/S. Trying them with chrome sentas (Not sure yet about the look…the chrome wheels with the back car is striking tho). Initial impressions are OK but seem to have some road vibration possibly due to incorrect balancing and will have to check into. I have put Michelin PS2’s on my original senta rears to match the front PS2s that I was running before. I will probably install sometime on car just to try out the PS2s all around….PS2 is probably my preference but went with the PS2 A/S because could not find anything other than run flats now in the PS2 and from what I have heard they cause noticeable performance degradation over non run flat tires.

 

do you have the factory alignment specs for the car ? i dont think rear camber spec is 0degrees, it should have some negative in it.

that being said the tires on the car are directional and cant be rotated without being removed from the wheel.

cornering and daily driving actually help keep rearwheal tread level.

my adivce to you is if you are getting uneven inner tread wear due to camber, bump up your air pressure gradually untill you get acceptable wear while never exceeding sidewall max psi.

in short- poor treadwear is something that comes with owning a vehicle with wide,staggered,performance tires.

for h20boy, your tires are over inflated if your getting too much center wear. bump your psi's down a bit in the rear.

 

That is exactly the course of action I took, however late in the tire's life. I dropped from 34 psi (recommended by Jag in the manual and under the armrest), to 32, down to 30 in the last 6 months. When my new tires are installed today, I'm starting at 29 in the rear to see if I can curb the middle wear rate just a smidgeon.

 

I guess I will start closer to the max PSI on the tires and see how that goes....right now I think I have all of the tires at 38 PSI and the max is I believe 51 PSI. When the rear tires were wearing poorly I believe I had the pressure at 38 PSI as well (although it could have been 36 PSI...I've slept since then :-). Interestingly on the 4000 mile trip I took I got about 22.8 MPG with my average speed really quite high.

 

Just think of the tire marks you will be easily laying down with those high pressures. Wait, that would be bad, right?

 

Hope it works out. Also if you can get a treadwear tool it will help alot, once the wear is uneven enough to see the only way to salvage the tire is by rotating (not possible). So the gauge can give you in-depth details at each PSI level every few hundred miles or so.

 

It is unusual but the Jaguar specs do not call for the rear suspension to be set to ZERO degrees for the rear toe. Slight to out is called for. This results in the inside of the tire wearing out. Great for handling but not for tire wear. The rear toe is adjustable on all of the XK's and best thing to do is set it for Zero or parallel. A 4 wheel alignment is best so you don't get dog legged. Make sure they will set it for zero and not just to specs. Although camber has an effect, it would have to be at an extreme to cause that kind of tire wear. Camber is adjustable through selective shim sizing on the rear. BTW: the front is also adjustable for camber if you swap out the lower rear a-arm bolts for the excentric ones. Center tire wear is an issue on the Michelin Pilots. They supposedly have remedied the problem but even with proper pressures, they will wear the inside tread first. I have 20" wheels with Pirellis and 25000 miles so far, even wear and about half life.

 

Wow...you are getting great tire wear...as I recall there are already eccentric bolts on the front lower suspension. Btw this is an 08 XKR convertible with 255 35 20 on the front and 285 30 20 on the back if that matters. The rear has some sort of trailing arm arrangement that would dramatically affect the toe if set incorrectly....in fact that is about all it would change as far as I remember. It is a simple tie rod arrangement with a locking nut that ties to the vehicle structure and to the aluminum wheel hub assembly. I will try and check the actual toe in to see if I can determine what it is set to. The wheels as I recall also have a noticeable cant (camber) and I will try and check this tonight as well...but I really don't have any idea what Jaguar specifies for the car....I can't seem to get any hard information on this vehicle other than a wiring schematic (not much good except for getting in trouble)...

 

Ok...here is the skinny. Rear wheels appear to have about 1.26 degrees toe in (I would say my margin of error is probably about 1/2 degree) which is composed of about .86 degrees (driver side ) and about .40 degrees (passenger side) in. The rears also have 1.5 degrees (driver side) and 2.6 degrees (passenger side) camber in (top of tire canted in). So does anybody here have any idea whether this is even close?