Gentlemen, I would like to use Michelin Pilot Sport A/S 3 plus tires on my 2014 Jag XJ 3.0 Liter Base. Specifically, the correct size tires that are available are front: 245/45 ZR 19 98Y and rear 275/40 ZR 19 101Y. Unfortunately, the OEM load index seems to be dictated by the original Pirellis that show a load index of front:102 and rear:105 vs. the 98 and 101 which precludes the use of Michelins. I have run the load calculations and the reserve weight margin on the fronts which have the lowest index is 28% (the rule is 20% reserve). My old XJ8 was 92 lbs heavier and ran 13 years without a problem using dealer installed 98 load index Michelins.
So, has anyone installed the Pilot Sport A/S 3 plus with any adverse experience besides tire dealers saying "No" after they look at the Pirelli sidewall or their OEM spec sheet? Michelin Customer Care also says "No" because of the OEM spec.
Is the conclusion that I cannot use Michelin tires?

 

Calculations used Michelin load index.

 

You probably would lose the right to sue them if you don't follow their recommendations.
On the other hand, I believe that's the type I've been running on my Corvette and Firebird's since the nineties.
I run them at 45 PSI as it states on the tire and haven't had a problem. I would guess the Firebird weighs about the same as my XJL.
Ford had tire problems back then because they recommended a lower tire pressure than the manufacturer said to use.
Ford was worried about the rollover rate on their SUV's and caused other problems.
Bottom line is you would be going out on your own, I've never had a problem with that myself.
Try a set and keep them at the recommended pressure and keep an eye on the edge of the tread.
If it wears faster than the center, it's not going to work.

 

I have run the Michelins for the last 6,000 miles at the pressures recommended by Jaguar on the door sill. They are outstanding tires in both the dry and the wet. The handling is outstanding. They make the car feel better on turn-in to the corner and are much more stable in the corner. They ride well and are very quiet. I am afraid they make the stock Pirellis feel like rim protectors.

 

I have always been under the impression that this is incorrect and that you should always run the pressure specified by the maker of your car. Car weights, corner forces, etc are all important in how your tire performs and you should use the tire pressure designed to go with those. Is this not correct?

 

It's my understanding that the PSI indicated on a tire is the maximum safe tire pressure not the recommended tire pressure.

 

It depends, as in everything else. Tires are a compromise, hard rubber wears well, soft rubber grips better. Ford lowered the recommended pressure on the Expeditions until they redesigned it because they rolled over too easy. That made the tires blow out causing rollovers. I can handle driving with a less than optimum tire better than a blowout at 125 miles an hour so I follow the tire manufacturers recommendation. If the tire says 45 PSI that's what I'll keep in it. Under inflation has a bad habit of moving the steel belt more and making it come loose and cut the tire to shreds.

I was coming down a short hill once with a truck coming down the other side. Half way down one of his tires lost it's cap off the trailer. It rolled into my lane and I met it at the bottom of the hill. I was able to lock up the brakes and slow enough not to be there when it was. I watched it roll off the edge of the road as I rolled past.

Any trucker will tell you that's what happens when you drive with severely underinflated tires. Most nontruckers blame it on recaps but it's really improper inflation. That's why truckers carry a tire bat to thump the tires everytime they stop. They can judge the inflation from the pitch when they thump it.

I always follow the tire makers recommendations especially if I'm not using the same tire it came with.

Saw your post when I posted XJsss. So I'll add an edit. When I started driving and buying tires I wondered about that and my tires said "recommended tire pressure 35PSI". All my tires until the nineties said that. When I got my first set of Michilins I checked and the tire shop had put 35 in it but I saw the tire said 45 but I don't remember off the top of my head if it said recommended or not. Still I ran them at 45 and later I put them on my Firebirds when they needed a set and I've run them at 45. Haven't had a problem with them or with the handling. After rebuilding my Firebird suspension with all beefed up components and aftermarket lowering springs, it takes corners like a Nascar as one guy told me.

 

rhomanski I beg to differ with your tire pressure settings using the max tire pressure molded into the tire. I am pasting the following from Michelin's website that underscores my previous posting:
Where can I find the recommended pressure for my tires?
In the vehicle owner's manual.
On a sticker on the driver's door or the gas tank door.
Do not use the number on your tire’s sidewall, as this does not indicate the pressure needed in your tire.

 

Gentlemen, thank you for the thread. I appreciate the dialogue on tire pressure. However, my main concern was with the Michelin Pilot Sport A/S 3 plus having a load index less than the OEM Pirelli spec. Was this of any concern in switching to Michelins?

MV Rider, are you running the Michelin Pilot Sport A/S 3 plus - front: 245/45 ZR 19 98Y and rear 275/40 ZR 19 101Y? If not, what are they?

 

That is exactly the tire and sizes that I am running. I am not concerned with the load ratings as I seldom carry more than one passenger or a full trunk.

 

Thank you, MV Rider. I now know what to buy to replace those awful Pirellis.

 

That's fine XJsss, I couldn't remember if the Michilins said max or recommended psi. Honestly though, I don't think it matters much because I've had 45 in every set I've had for the last 25 years and they wore evenly on all my cars. I like the Michilins, they handle well and last a good long while.

Sometimes people can be too involved in right and wrong. The FAA told us in the 1990's that we had to do engineering orders exactly as written. So the engineers would go look at one plane and write up a change. One B-757 had corrosion on a ground stud, they decided we should replace the ground bracket and we should replace the hardware. They gave us specific part numbers for everything. When I got to the end of the job, I found Boeing had added a couple more grounds to the stud than the plane the engineer looked at. Since I wasn't allowed to deviate I had to stop and wait for an engineer to come to work. Instead of getting the same bolt in a longer size, I waited and gave it to day shift unfinished. I gave the guy the longer bolt that fit, the engineer asked what's the part number when he came by and wrote up a deviation. To the FAA it only matters if your job description is technician or engineer. What's funny is the engineers were paid $35,000 to $40,000 a year and a technician was topped out at $65,000. Of course that was twenty years ago.

Bottom line though is sometimes you can nitpik things beyond reason. I'm not talking about you but I have met people that just loved to prove others wrong for the most ridiculous stuff, such as spelling or whatever. There was a guy like that on my crew, he was a trial. He did that to everyone on the crew except one guy. They were both devout Clintonites so I guess they thought they were morally superior to conservatives. Anyway happy motoring.

 

So my point is not to be be right or wrong, but the cars suspension (springs, shocks, bushings, alignment, and tires) are all designed to work as a unit to deliver ride, and handling as an integrated unit. So the tire pressure and design are all important to the car. Lastly i was looking at the tires recommended for MY2015 XJs on Tire Rack and it was strange that the 20" tires are lower weight rated than the 19" tires, but they are also recommending the Michelin tire the OP wants to put on their XJ. BTW my XJ only wears Michelin tires.

 

I can't tell you what's on mine. I've only put 100 miles on it so far. I checked the tread and it was good and the carfax said they were only a couple years old.
I can tell you it will have Michelin pilot sport on them and I will run them at 45 psi.
No matter what, enjoy the drive.

 

I don't believe it is a safety issue but more a ride issue. The lower PSI gives a better ride. If you are happy with 45, then 45 it is. I also don't think tire manufacturers give a "recommended" tire pressure, only the max pressure. They leave it up to the car maker to decide what PSI is best for their particular application. Some people lower the PSI to 15 while driving in snow to allow more tread to be exposed to the road. It is all about the specific application.

That said, I would think a higher PSI would not handle as well due to the tire being harder. It would be interesting to see testing of the same car, same tires, at difference PSI. I suspect that is out there somewhere!

And just as an FYI: I too always used to fill my tires to the max printed on the sidewall. I did this until I read up on tires, pressures, handling and the reasoning behind manufacturer ratings.

 

Let's deal with the gross inaccuracies in the above regarding the Ford story.

1) It was Ford Explorers.

2) Ford wanted a lower tyre pressure to make the ride nicer.

3) Firestone/Bridgestone, their OEM supplier, sent Ford a memo telling them that the tyres Ford wanted to use had a minimum safe pressure of 30 PSI.

4) Ford didn't want to hear it and put 26 PSI on the door jamb sticker.

5) The average US user was running a lot less because they never check their tyres.

6) Come the hot period here in the desert SW, and the underinflated tyres burst with alarming regularity because they were overheated.

7) The NHTSA and other agencies determined that the rollovers were almost ALWAYS caused by the driver over reacting to the blowout.

Yes, I do know a lot about this because we had saturation coverage on the subject as NHP, CHiPS and AzHP were scraping up the bits on a weekly basis.

As for running the MAXIMUM pressure in tyres at all times (which is what the sidewall number 45 PSI relates to), my rev counter says the maximum for my engine is 6000 RPM, but I don't keep it there at all times.

This "fill it to the sidewall" nonsense is something I never saw until I came to the US. I. Don't. Get. It.

 

Well since you single me out, I guess I'll reply.
Basically you say the same thing I said except you repeat the FOMOCO tale about it being for ride comfort when national and local news eventually reported it was for the rollover rate in accident testing. Oh and you corrected the model. Well thank you for reading the wikipedia page and reprinting it for me.

I wasn't really interested in reading it myself just to please you. I would also like to thank you for wasting a few more precious minutes I have left on this Earth to feed your ego. I hope you feel much better about yourself. I was just trying to help the OP in his questions. Perhaps you should try to help instead of fault finding. That's the best way to feel better about yourself.

 

At a bare minimum I would like to get a couple things across about tires. Underinflation can cause the belt to come loose and cause adverse wear.
Tire pressure changes as you drive, it will increase as the tire warms up. So keep it a few PSI less than you want as a maximum.
Check the tread wear regularly and run your hand carefully on the inside edge, feel for the steel belt coming out. It will cut you if your not careful.
Be careful if you add air. Stay on the tread side off the tire, never crouch or kneel next to the sidewall. When one blows it will blow out the sidewall.

Just before I retired, one of the HERO guys in Atlanta stopped for a woman with a flat. He turned on his compressor and ran up and started filling the tire,
kneeling next to the sidewall when it blew killing him instantly. I assumed although it was never said that she had 2 piece aftermarket rims and they came apart.

In jets we will put up to 300 PSI of nitrogen in the mains. We always removed the tire and sent it to the wheel and tire shop. They deflated it, removed the tire, and split the wheel. After checking it, they would marry the wheel back together, mount a tire, and put it in a steel cage. Then they would inflate it from about twenty feet away. The halves are held together by a continuous row of bolts. If one breaks you can have a zipper effect where they all break and the wheel blows out to the side. Many people died teaching us that procedure, we don't need anybody else teaching it again. So be careful.

 

You shouldn't take apposing viewpoints personally as every single qualified source I have ever seen, bar none, says not to use the max tire pressure printed on the sidewall. What you says flies in the face of what tire makers, tire sellers and automobile makers say not to mention conventional wisdom. You provide only anecdotal evidence that this is a good thing. Nothing at all that is scientific and no corroboration of your opinion is provided. Don't feel offended if people don't wish to take your word over the many, many qualified sources that say otherwise.