I pulled back the cover today, unhooked the battery minder, fired it up, and headed down our road to the highway. There was the usual initial minor roughness for at least part of the two mile stretch to the highway, but it was completely gone by the time I got onto it...and nothing but smooth sailing and a grin ear-to-ear after that. The friend riding with me couldn't feel anything when asked.

The car sat on the tires without moving for 3 months through temps down to below 0 F, and it was below 40 when I started driving it today. I usually add a few extra psi before winter storing to help minimize flat spotting, but didn't this year, and these felt no worse than the Pilot Sports and Yoko's do after winter storing on my other sports cars. I did however notice minor initial flat spotting every time I drove the car last fall after it had been parked overnight, but it's gone again after a block or two.

I know Rahtok, RJC and perhaps others have experienced issues that they suspect are related to the car sitting for long periods of time on a dealer's lot, and I was concerned I might find the same today. But 3 months parked in the Canadian frozen tundra seems to have caused no problem at all. I wonder if being parked in hot southern states is somehow harder on the tire, or whether they just happened to each have a defective tire that's gone out of round.

Bruce

 

Thanks for sharing that info it will be interesting to see what happens when you drive your car again to see if you get that initial roughness, as the initial roughness you reported is actually a form of normal temporary flat spotting on low profile tires from the car sitting for extended periods; please let me/us know.

This weekend we had my Father's car jump started that sat idle since he became very ill in early Sept and there was no roughness/vibration at all, even for the first few miles; my wife and I were amazed. He has Michelins on his car and it was sitting in his parking garage the entire 6 mos.

My Jag smooths out after the first few miles too but the vibration returns after sitting overnight again, this no doubt is not normal; a few weeks to months yes, but not overnight. I also have a shimmy between 50-75 mph even after the tires are warmed plus a brake judder, something's not right. I will check all the tire pressures tomorrow.


Here's an excellent article on flat spotting from the tire rack. There is temporary flat spotting and permanent, appears mine and Rahtok's may be the latter...

Tire Tech Information - Tire Flatspotting

 

Thank you for the link. I should have taken all weight off the tires over the winter, after each track session last fall, and added air yesterday to recommended pressure before parking it last night. It would seem I have broken every rule in the Tire Rack book, and have for years on various other low profile tires without permanent flat spotting, so I'm hoping that I'll have dodged the bullit again this time! I'll find out soon enough.

I haven't daily driven the sports cars in the past so I'm used to the expected temporary flat spotting. I hope to install a lift in the garage this year, the type that takes all weight off the tires, so that will at least provide relief for the next set which should be Michelin Super Sports. Until then I plan to drive it like I stole it on the Dunlops, hopefully on both the road course and auto-X, to become well-acquainted with the XKR's dynamics before tossing the Dunlops!

Bruce

 

There are special tire savers that you can put under your tire that keep the tire from developing flat spots when stored for long periods of time. They are in the shape of the tire where the tire contacts them.

I personally have not experienced any flatspotting on my XKR. Interestingly when I had my 3000GT years ago I ran Bridgestone tires and they would flatspot overnight, especially when they got some age on them.

 

Bruce, what rscultho is talking about are called Tire Cradles, I actually have a set and they are a pain to use for daily parking since they can move around as you have to get up enough speed to drive up on them (can be a bit challanging if there's a slope to your driveway leading up to the garage) and trying not to brake too hard as they will slide and you can drive over them as the back stop is not that tall, but they're great for long term storage. Here's a link Welcome to TireCradle

 

What rubber are you running on your R?

 

Vredestein - outstanding tires.

Quiet, great grip, great ride, and an interesting and different tread pattern. They have been great in both dry and wet. Have had them on for about 6 months.

I have had Michelins (several styles) and I am not as big a fan as others. They never lasted very long for me and as they wore/aged and the performance/noise degraded significantly. And they are expensive as well.

 

Very good to hear about Vredestein

Michelins may wear fast (depending upon the type) and are expensive but their quality consistency is superb and their performance is excellent.

It's also good to hear that with the right tires the XK/R's don't have inherent vibration issues.

 

Almost every Jag I've owned together with every set of tires I've had on em develops flat spots over night, irrespective of tire brand. Worse in cold climes to be sure. This flat spotting has aiways cleared up after the first mile or so.

I have always attributed this to the Jag suspension set up and my own finely attuned automotive sensibility to vibrations, incidentally, the last of my senses not artificially augmented. LOL

My point is, don't be too concerned about tire flat spotting that goes away after a few miles. If flat spotting persists after normal operating temp is attained, take 2 aspirin, a shot of Jim Beam and buy new tires. SOAB!

 

I drove the car again today, and while the first half mile is uneven pavement, by the time I hit smooth road there was no perceptible flat spotting what-so-ever. Apparently my Dunlops don't suffer from anything but the most temporary of flat spotting...even under abusive and neglectful conditions. Halleluiah!

OEM 20" Maxx Sports, 24 months old, ~10,000 miles

Bruce

 

Glad to hear that Bruce.

Are your tires noisy at 10,000 miles ? Mine are with only 450 miles especially from 30-50 mph. Hoping the Pilot's are quieter.

 

Appreciate the levity...got to keep our sense of humor about these kinds of things.

The temp flat spots would not be the worst thing for me but the car really shakes for the first few miles. The shimmy from 50-75 after the tires have warmed is a PIA as is the brake judder. Does your steering wheel have any hands off shimmy at any speed once the tires are warmed? What tires are you now running?

 

My tires are very quiet and free of any kind of vibration. The whole car is incredibly quiet, especially considering it is a convertible. It's so quiet I actually checked it last fall with a sound pressure meter and recorded an incredible 64 dba at highway speeds which I posted in another thread! The only sound you notice is the exhaust if you select dynamic mode.

I'm not given to exaggeration, unless of course I'm talking about my driving ability, so when I say the Dunlops are quiet you can take it to the bank

You simply have a set of messed up tires that need changing, and while I think the Michelins will be a better tire as the Tire Racks surveys have found, I can not fault the Dunlops as a pretty decent tire on the car. I sure hope the Michelins will be as resistant to flat spotting as the Dunlops because those Tire Cradles sound like a pain.

Bruce

 

Thanks for your feedback.

The tire cradles are a pain for everyday use, at least they were for me and that was long before my spine was messed up.

Hope to get the tires, brakes and some other odds and ends done in the next two weeks.

 

I'm running Continental Extreme Contact DW tires. This is a high speed Summer performance tire that compares favorably to the Michelins. Shake and shimmy at 50 and above is not good. I would suspect alignment. Have you tried Road Force Balance? I have no steering wheel shake at any speed.

Relative to noise, my belief is that all season tires are quieter, longer due to compound and noise suppression built into the tread design. Why I don't currently have all season tires is a whole nother story. SOAB

 

Thanks THC

The dealership already ordered new Michelins for my car so I'm sure they'll check the alignment and also balance them on the GSP 9700.

I'm glad to hear shimmies are not inherent to our XK/R's.

My Dunlops are noisy as hell st lower speeds, reminds me of the old style Goodyear Gatorbacks.