2003 STR 61K miles

The tires were put on the previous owner, and since buying the car, I have put approx 12K on them. I am religious about keeping them at 35 PSI.

Long story short, after getting my new oem struts installed today the mechanic called me up and said you need new tires ASAP. Flabbergasted, he explained to me that because they are low profile they need to be at a higher PSI than the current 35. Since I have been running them at 35PSI, he said that the sidewall is shot and they are almost not safe to drive on. I respect his opinion because he does good work but nonetheless would like a second opinion. Also his shop does not install tires, so I feel better knowing he is not trying to upsell me on parts I dont need.







I can definitely see the wear, especially on the front two tires, but am confused if it really is the end of the world as he said it is. thanks

 

Ask him to explain why I see no need but I cannot see the inner side of the tire.

 

I see a little scrubbing on the tread edge, nothing much beyond that (?)

 

+1. We need to see the inner edges as that's where the tire is most likely to wear down to nothing if that is the case.

 

I agree, what do the inside edges look like?

Have you seen the alignment info in the how to section?

 

These are the std tyre pressures from the 2003 NAS manual:

Tyre size ...Speeds below 100 mph ..Speeds above 100 mph
225/55 R 16 ...Front 28 lbf/in²...............34 lbf/in²
235/50 R 17 .. Rear 32 lbf/in²................38 lbf/in²


245/40 ZR 18 ...Front 28 lbf/in²..............31 lbf/in²
(not ‘R’ models) .Rear 32 lbf/in²..............35 lbf/in²


245/40 ZR 18 . Front 28 lbf/in² ..............36 lbf/in²
(‘R’ models)
275/35 ZR 18 . Rear 32 lbf/in² ...............38 lbf/in²
(‘R’ models)

 

Read the date code on the sidewall and figure out how old those tires are. They look kind of dried out.

 

I agree, I had some go like this, turns out the place that used to clean my car used to dress the tires in an oil based product to make them shiny and it dried them our after about a year of them using it every week

 

Keep in mind that the higher the pressure you inflate a tire, the more that tire will wear down the dead center and the less that tire will wear on its edges....

Ours is a base S-Type, not an R, but I've always kept its tires at around 33 to 34 psi year-round to achieve an optimum balance of long treadlife, smooth ride, and quiet at speed. I believe that your chosen pressure of 35 psi is well within the optimum range....

 

I appreciate all the responses and thank you for verifying that the factory calls for 36/38 front/rear psi as confirmed by the sticker in the door jam.

Here are the pics of the insides. I skipped the fourth tire because it only has a few thousand miles on it from someone forgetting to pick up their nail they left on the freeway. Car has been aligned since the first week I got it (49.5K miles) to the "Brutal Specs."







I am going to Discount Tire tomorrow to get another opinion. Thanks

 

Get a second opinion from another shop!

 

I had tires on another car that were not safe to drive because of the sidewalls but I could feel it in the steering. It felt like tie rod ends were worn with play in the wheel. They also gave a very unstable feeling if you accelerated from a stop with the wheels already turned. The sidewalls would flex and feel very unstable. You didn't mention any of this so it might be interesting what info. you got from Discount Tire.

 

I can't tell from the pictures but sidewall damage is sometimes hard to see until the tire is dismounted.

But the guy is completely wrong about ruining the sidewall by running them at 35 psi. That is just plain wrong and I would be suspicious of any other statements this tire expert makes.

About his last statement. Tires are to be run with the pressure recommended by the tire manufacture. What does the sidewall on your tire say?
The car manufactures generally want you to run them a bit low for a softer ride but we are only talking a few psi.
.
.
.

 

Sorry, no. The tire manufacturer has no idea what car the tires will be fitted to and specifies only the maximum safe pressure irrespective of vehicle type.

It is the car manufacturer that determines the correct optimum pressure.

 

Wrong. Car companies do not make tires. Tire companies do. That's why the pressure are imprinted on the sidewall. These numbers ALWAYS are the final answer.

As you said how is the car company to know what tire is installed?
.
.
.

 

Well if the tire company has no idea what type of car the tire will end up on, and the car company has no idea what tire will be installed, there's no way to determine the correct pressure.

We're all screwed.

OR:

http://www.michelinman.com/tires-101...-pressure.page

Compare the measured psi to the psi found on the sticker inside the driver’s door of your vehicle or in owner’s manual. DO NOT compare to the psi on your tire’s sidewall.


........


3. The manufacturer's recommended pressure on the door jamb is a great place to start. It will list a recommended pressure or pressures,

http://blog.tirerack.com/blog/bens-b...-in-your-tires


.......

Set according to the vehicle manufacturer's cold tire pressure(s) recommended on the vehicle's tire placard or in its owner's manual.

http://www.tirerack.com/tires/tirete...jsp?techid=147

 

Tire pressures are tricky thing, in my view the is no one guide to follow but in general as long as you don't go above or below the recommended pressure you should be ok.

I prefer the feel of 38-40 all round depending on tire manufacturer and have never had any uneven wear or catastrophic tire failure but other folks might prefer a "softer" feel of 35, it comes down to personal preference, the speed you normally drive at and weather conditions.

 

The sidewall is the max for the tyre.

The car / handbook tends to assume you've used the exact tyre the OE fitted.

The jag handbook for my car gives pressures for below some speed and above that speed (I regard it as motorway speed, if not our motorways!) and also depends on load (weight).

However, going up by 1mph (from the low figure) cannot suddenly change the required pressure by quite a jump. So there must be a range of pressures that are safe and exactly what one chooses... well, to some extent personal choice.

To some extent you may have to tweak to suit the actual tyre and conditions.

What I actually do is pick values within the range mentioned above, generally above the middle, make sure handling is good, then watch tyre wear.

Avoiding underinflation is vital. Apparently many on our roads do in fact have substantially underinflated tyres, even so.

 

50% of the cars I'm behind seem to have at least 1 obviously underinflated tire

 

^^

JagV8 gets the gold star.