Just returned from the tire shop after replacing a front tire on my XF SC due to a distinct bubble in the side wall which protruded a good 1" and was about 1.5" wide. This is a 255x35 ZR 20 Pirelli P Zero standard equipment.
The shop said it is not unusual for such low profile tires to show such a bubble if a pot hole is hit fairly hard. They also showed that the Pirelli warranty language excludes such from coverage.
So with only 2550 miles on the car, it's a new P Zero at $515 installed and balanced. (Tire Rack price is $465 with no installation of course).
I'll be watching for pot holes more carefully.

 

tirerack would be no better to deal with. we were 10 year customers of them and they refused to do anything after they sent us 2 defective sets of continentals in a row. I dont know if they were hoping we wouldnt notice or what. one even had a bubble on the inside of it and a belt had shifted. Continental also wanted to not help. Im conisdering a lawsuit against both of them.


i guess only you know if you indeed hit a big pothole....

 

We may be reaching a point where the tires are too low profile for all-round use. Tires are supposed to be able to absorb impacts, but they need space to do this. A 50-60 series profile tire has this space, but a 35-40 series tire lacks this. Another issue I see is unsprung weight. An 18" rim will weigh more than a 16" or 17" rim all other things being equal.

Mike

 

The roads around here are terrible. The 225/45x17 Pirelli PZero Rosso on the right rear of my 2002 X Type developed this damage and I was unaware of when. What happens is the sidewall gets pinched between the rim and the obstruction and the cords break. High performance tires have thin sidewalls without much resistance to this kind of impact damage.

Fact is the ultra low profile tires are a styling phenomenon and do nothing useful for real world handling.

I bought my base XF with 18 inch wheels for this reason. The 45 series tire is low enough profile for most road use. Anything lower is asking for this kind of problem.

And no it isn't warranty because it isn't a defect. 78 series tires just didn't suffer from these types of impacts.

 

If you have a Discount Tire in the area you should be able to purchase their "Road Hazard Certificates" for your factory tires. (Check their website for more info.) We did this with the tires on my wife's Volvo C70 (predecessor to her XF) and when one of the tires developed a bubble they replaced it at no charge. I have not yet bought the "certificates" for the XF. Our Jaguar dealer offered us similar coverage when we purchased the XF, but it was pricey compared to the cost of the "Certificates" on the Volvo so I figured it would be cheaper to go through Discount Tire if we were going to do it for the Jaguar.

 

I do get a road hazard warranty on the new replacement tire (;>).

You guys all have it right; these low profile tires have zero practical advantages. Look at racing, there's no series that uses them for the reasons you all cite, plus the fact that they effectively minimize the range of spring rates available (a tire is really a variable rate spring). Formula 1 tires look to be as high profile as anything on the road and this is the highest tech racing.

 

We regularly sell road hazard protection policies with new car purchases here in Michigan. The latest statistics show our roads as the worst in the nation for 5 years running and this year the reporting entities said our roads are the worst by "a factor of 2" meaning that our roads are twice as bad as the next nearest competitor. I have a regular customer with an XJR that has 20" Sepangs and he is now on his 3rd road hazard policy for the same car. There is a maximum limit to the amount they will cover and you should make sure you are aware of that amount. This particular customer has had more than $5000 worth of rubber replaced on his car due to road hazards at no cost to him thanks to the hazard protection. Most policies do not cover damage to the wheels though unless the wheel is actually cracked and wont hold air, bends don't count. He has had to pay at least $1000 in wheel repairs out of pocket.

A tip for those of you that do purchase road hazard protection for your wheels and tires. Only non-repairable leaks are covered, only cracked and leaking wheels are covered. There is no coverage for hitting things like curbs or parking blocks, those are not hazards, those are operator headspace errors. Keep those points in mind when you do take your car in for tire coverage. Don't tell your service advisor you slid into a curb, you always hit a pothole. Don't say you have bubbles in your sidewalls(not covered, not leaking) say you have leaks in your sidewalls that wont hold air. Don't call the tire warranty company yourself, let the service advisor do that for you, they know what to say to be sure to get coverage. If you have more than one tire with a problem at one time be prepared for a stay of 2 or 3 days at the dealer. A request for more than 1 tire often causes the insurance company to send an inspector out to asses the damage and take pictures especially if we are talking about 19" or 20" tires at +$500 each. If you are claiming broken wheels there will be an inspection required regardless of how many you are asking for. If you are untruthful about the extent of the damage and the inspector finds no cracked wheels or sidewall bubbles that are not leaking future claims will always require an inspection and I don't know of any tire policy that covers rentals.

Finally, one horror story for those interested in tire coverage. A customer with an X-type had purchased road hazard tire protection policy. He completely drove the car over a curb and blew all 4 tires and bent all 4 wheels but the wheels still held air, no cracks. The service advisor told the insurance company that the customer had hit some metal debris in the road that flattened all 4 tires and bent all 4 wheels. The insurance company sent an inspector out to asses the damage and he found that all 4 wheels would hold air but the tires were ruined. The insurance company authorized replacement of all 4 tires at no cost to the customer but he would have to pay for wheel repair. The customer was upset that we couldn't get his wheels replaced under his hazard policy. He took it upon himself to call the insurance company and plead his case. He told them how he had driven over a curb and bent all 4 wheels and blown all 4 tires. Of course the insurance company said "oh really, we thought you hit some metal debris in the road. Since you hit a curb you have no coverage at all and we wont pay for anything". This customer actually came into the dealership the next day complaining how we had jacked him over with the tire policy and we should replace his wheels and tires at no cost anyways.

Sorry for the ramble but most of it is good information.

 

Yep, I hit a manhole cover the other evening and have a nice bubble on my front tire with around 5000 miles on my SC XF. I ordered a tire mail order for around $430 and now need to get it mounted. When I bought the car, the Jag dealer offered tire protection but it was not something I thought was worth buying.

At some point I'll probably get 19" rims with all season tires. Probably after the original Pzeros are worn down.

 

I agree I've never had trouble with pot holes on my vehicles that don't run the low profiles.

Like the rover I hit rocks with it and the 255/85's just take it all day long

 

If I remember the math, a 255x85 has a sidewall that's almost 9" high. I think you could take the springs off and still run over things with no problems at all .

 

Just had to add my two cents... I stumbled on this looking for pictures of my dream car...
I find it interesting that so many people seem to have problems with lower profile tires. I did the first time I switched but learned some lessons.. Also, low profile tires are the choice for performance on a street car. You can't compare a race car to a street car. First of all, the tires are totally different that street tires, also the suspension plays a very major role. If your street car had a suspension set up to corner on a high profile tire, there would be little to no suspension travel. ( notice how much vibration is visible from the in-car camera on a race car? ) A race suspension in a street car would make your interior bits fall off. How modern engineers create cornering force along with an acceptable ride is to tune a more compliant suspension to lower profile tires. I good example is to drive a 80's vette along side a modern one. The older car will corner well, but also has a very very stiff ride while the modern car is much more comfortable yet will also out corner the older car. One of my little tricks when it comes to low profile tires is to shop for an increased load rating. If you get a tire rated at a larger weight than needed, you'll end up with a more resilliant tire when subjected to road hazards. Most cars I've put 35 or 40 series tires on have called for a load rating of about 95 but I look for tires in the 98 range and have not had an issue with bubbles, ect. And that is driving on Ohio roads, some of the worst in the country.
Sorry for the rant...... I'll go back to picture looking.....

 

F1 tires are tall because of wheel size and tire width restrictions. The tires form a substantial part of the suspension compliance.

However, race cars do not use tires with very short sidewalls because they don't work well. The aspect ratio may be low profile but that is because race tires are so wide.

Unless the roads you travel on are very smooth these 30 and 35 series tires are just a dumb idea. They are ONLY for appearance and fashion.

Road & Track did an interesting comparison a few years back and determined that you can go too low and performance starts to degrade.

 

Sumthin to think about guys -

I needed 2 new front tyres some time ago, either Continentals or Pirellis were my choice for my A6....225 X 50 X R17 usually with a load index of at least 94 although 98 was preferrable.
2 tyres fitted n balanced £320 approx
I checked Ebay and found a brand new set taken off a 08 Audi TT. The tyres alone were worth over £600, each rim costs £400 approx from the dealer, Total £2400.00
I got all four rims incl new Continental Contact Sport 2 tyres delivered to my door for £435.00 total
see example below

Genuine_Audi_17"_Alloys_c/w_tyres


Just a thought and worth checking out to see whats available for the Jag?

 

Very true that there are cases of extreme wheel and tire size that degrade performance. And, style plays a part in an OEM's choice in stock tire size. I would agree that a Civic running 20's is absurd. Here is an engineering forum link that some of you may find interesting. It goes into the properties of tires and the trade offs based on size and load. I warn you, quite dry but very informative. It's also old but the post is still there.
http://www.eng-tips.com/viewthread.cfm?qid=56923&page=4