Hi, Ive been lurking around here for a while, finally decided to ask for some help. Im the owner of an 03 Jag Stype R in Jag racing green, 80k, beautiful car.

My stype r has 235/50/18 tires up front instead of the jag recommended 245/40/18 . The tires up front are brand new, put on by the dealer, not being the recommended size is this something that I need to address? Could the taller, thinner tires be causing increased wear or damage to the car or perhaps be the reason for the occasional rpm bounce/yoyo of 30-50 rpm Im experiencing usually when driving up hill? Any help/opionions would be appreciated... Thank you!

 

Hi rts,
Not good news, eh? I mean, here is a Jaguar dealer . . . fitting tyres that are not up to the clearly documented specs issued and distributed by the Jaguar manufacturer? Not only that, but this is for an STR - clearly the highest performance of the model range.

No, these tyres will NOT, of themselves, DAMAGE your car . . . and, I accept that some will see my remarks as fairly angry. They're right! Even in the face of an owner insisting on the "cheapest fix possible", I just cannot conceive of any Jaguar dealer agreeing to fit clearly sub- spec parts with such a safety impact as road tyres.

Firstly, I would seek advice as to any redress you may have of the dealer. Sure, approach them amicably . . . but do so armed with knowing your rights . . . and ask, politely but firmly, that they be replaced. How hard you press the issue, or report them to your national distributor or Jaguar Cars UK, is up to you . . . but what point is there in the manufacturer issuing specs if owners (at their peril) or dealers (incredible!) ignore them?

While you're at it, check the rear tyres, coz that's an even more critical issue on the STR, and especially if they have also suffered in the hands of someone unscrupulous enough to scam a few bucks per tyre by fitting sub-spec replacements. Finally, and as soon as this matter is redressed, find another dealer. My experience here in Australia, but also as reported by JF members worldwide, is that there are any number of ethical and trusted dealers. I am sure there will be others closer to your location who will be happy to recommend reputable dealers.

Best wishes,

Ken

 

Thanks Ken, I appreciate the reply. I should have checked the tire size before I left the dealer. I just assumed they would put the correct size tire on the car. The dealer is about 350 miles away abd Ive had the car for about 6 months and just discoverd that the tires arent the right size so I will probably just live with what on there if is not hurting anything.

 

Using an online tyre size calculator they're out by far more than recommended.

I'd be worried.

I hope they're a top brand and are rated for the car. They may well not be and if not I would change them.

Be certain to check the rears. They're very important too.

No budget tyres, no out-of-spec ones...

 

The rears are the right size, they are Toyo Extensa HPs which Im not really a fan of. The tires in the front are out of spec sumitomos

 

Phone the dealership, ask for the service manager, explain the situation calmly and rationally while also managing to point out that the front tires are potentially dangerous, and ask for their assistance. If the service manager refuses, go up the ladder to the general manager. The GM should realize that his/her dealership can be held liable for any negative occurrence associated with improperly-sized tires that his/her dealership installed....

 

This seems like a tech made a decision at the time. That may have been what was in stock. I have 235/50/17's on mine and they are correct. It will affect your speedometer reading, but not much else.

The smaller size turns less revs per mile 763 verses 808 but your 60mph is actually 63.7, 70mph is actually 74.4.

 

They are not correct for an STR, are they?

BTW I think 17s would not even clear the brakes on the OP's car.

 

It was a smaller lot and not a jag dealer and they are unwilling to help me out. If the out of spec tires aren't increasing wear on the car and dont pose safety hazard Im just going to live with them until Im ready to replace the rears and do all four at once. I appreciate all of the responses!

 

They may be a hazard.

What is their load rating?

 

The correct STR size is 245/40/18

 

They are Sumitomo AS P02 101W tires max load 1819 lbs

 

Well at least they'll cope with the load, torques etc.

 

Surprised you are not in limp home mode??

So they must be pretty close to same diameter. It does not take much difference between the front and rear tire diameter to throw off the computers. Usually the ABS is unhappy about the different tire RPM's.
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I do get the traction control coming on occasionally under normal driving conditions when making turns. Could the largest tires be causing that?

 

Yes. It may well have stored codes (in the ABS module).

 

Alright then I will have some spec tires put on. Thank you everyone for the help.

 

True. I was just making the point that there are several sizes depending on which model S you have. Some of the six cylinder models use 16 inch wheels.

 

Yes - though this entire thread is only about an STR. (And indeed an 03 one, which will have the massive Brembo brakes.)