csertich

New Pilot Sports installed today, after running Continentals for the last 14k miles. I was out in the rain with my Conti's a couple of weeks ago (only the 4th or 5th time in the rain in 4 years) and they were dangerous. Today, it was raining as I drove my car back from the shop-what a difference. Steering was a little lighter and more alive with more feedback. The changes were subtle (except for actually having traction on wet roads) but noticeable.

Now my question-Is there a technique for properly breaking in a new set of tires? What should I be doing, or not doing. Anything special?

I was kind of thinking of riding the clutch during smoky burnouts but that was really to get my car ready for the RS clutch and lwf. Probably not a good way to break in the tires.

Thanks to all,
chuck

Full Boost

Chuck,

The ONLY thing to do is to take it easy for the first 20 - 30 miles - it will wear off the protective coating that they come with....

The "other" important thing is PRESSURE!! Wrongly inflated tyres are the biggest cause of premature tyre wear....

Best,

Simon.

epj993

Yep, great tires. To break in, you just need to log ~200 miles or so to wear off the manufacturing release and get maximum grip.

Edit: You beat me to it, Simon!

csertich

Thanks guys. I got the car home, let it cool for about three hours, and checked the pressure. Tires were at 44r and 40f. I quickly let out some air and are now at 40r and 36f. I will probably go lower thru trial and error.

I also checked torque settings on all bolts and it seemed right on. But I loosened them all anyway and re-torqued just for the heck of it.

Thanks Again!!!

fast_freddy

I run cold pressures in the AM in the garage (no sun) at 40# rear and 32# front. Tires are Pilot sport ribs 225/40x18 and 285/30x18. The Porsche recommended pressures of 44# rear and 36# front are way too high for our driving purposes in the US. Those higher numbers are for the autobahn

geolab

The tire pressure recommended by porsche is for the good mainstay of the tire more than the car.
A 2.5 bar in front and a 3 bar at the rear is the minimum you should inflate the tires in my opinion.
Remember, every tire manufacturer states that over inflated tires is not a problem as much as under inflated
tires is dangerous !!!
remember also, that one of the tricks to avoid flat spots, is to over inflate.
BTW, on the autobahn at continuous high speeds, my cold tires inflated at 2.5 bar (36) and 3 bar (44) (porsche manual)
rise in the summer heat simultaniously to 3 bar and 3.5 bar after a few tens of miles...
some serious reading should be done on this, and as fo me, I would never under-inflate the tires.

DJF1

And you dont find dangerous that your actual pressure on your rear tires raises to 51 PSI and higher which is the maximum inflation of every performance tire?
Try 44 PSI cold on the track and its a great recipe for disaster.
Porsche also specifies 36 on the rear with the 17" inch wheels. That should make one think that the recommendation has something to do with the tire construction especially with the shorter side wall of the 285/30 tire. That was 12 years ago...
Personally I use 265's on the rear and my cold tire pressures on the street at 34 front and 36 rear. When I used to run on he track with street tires, anything over 40psi Hot would result in lurid slides, overheating of the compound, chunking of the tire and outright dangerous behavior. I cant imagine running at full speed at 51 PSI or more risking a tire explosion.

My .02 cents...

geolab

No, I do not find it dangerous to inflate my tires to the manufacturers recommendation.
If my tire when hot reaches the maximum inflation for performance tires, as you say,
I know that the tire can run at a higher psi because the max recommended should be when the tire is cold.
I did not recommend 2.5 bar front / 3.0 bar rear when cold,
It is in the porsche 993 manual, and on my door sticker.
I have 225/40/zr18 - 285/30/zr18.

Every tire specialist warns !!! better over-inflated than under-inflated. It is even on the
Highway flashing banners in germany and the UK.

Remmember, I am not recommending over-inflating, I am transmitting the warnings I see of under-inflating
As for myself, I inflate my tires to the recommended pressure.

But on your experience point of view, DJF1 you might have a point here.

a click on tire rack and I found this:

quoting tire rack:

Disadvantages of Underinflation

An underinflated tire can't maintain its shape and becomes flatter than intended while in contact with the road. If a vehicle's tires are underinflated by only 6 psi it could weaken the tire's internal structure and eventually lead to tire failure. Lower inflation pressures will allow more deflection as the tire rolls. This will build up more internal heat, increase rolling resistance (causing a reduction in fuel economy of up to 5%) and reduce the tire's tread life by as much as 25% while increasing the probability of irregular treadwear. Drivers would also find a noteworthy loss of steering precision and cornering stability. While 6 psi doesn't seem excessively low, it typically represents about 20% of a passenger car tire's recommended pressure.

Disadvantages of Overinflation

An overinflated tire is stiff and unyielding and the size of its footprint in contact with the road is reduced. If a vehicle's tires are overinflated by 6 psi, they could be damaged more easily when encountering potholes or debris in the road, as well as experience irregular tread wear. Higher inflated tires cannot isolate road irregularities as well causing the vehicle to ride harsher and transmit more noise into its interior. However, higher inflation pressures reduce rolling resistance slightly and typically provide a slight improvement in steering response and cornering stability. This is why participants who use street tires in autocrosses, track events and road races run higher than normal inflation pressures.

97Targa

DJF1

Geolab, interpret what I said as you wish. The beauty of RL is that it allows experiences from everyone to be shared. If you read the archives you will find many experiences from everyone. If you read what I said you will also understand that the recommendation as i suspect is for the 285/30 tire, short tire wall etc. Not necessary for a 265/35 or a 295 or a 305 for example. The 285/30 tire on Hoosier for example had some catastrophic failure on 285/30 size, Hoosier recommended more inflation ( to keep the sidewall stiffer) but that had detrimental impact on grip and at any rate Hoosier stopped recommending the 285/30 size for 911's. That example should tell you why the recommendation from Porsche is as such. Certainly the 265/35 rear size do not have the same issues as the 285.
My point though is that no one should be making a blanket statement regarding tire pressures. Indeed they vary with size, construction, tread and manufacturer. Porsche and any company in the world can never go into so much detail and assign different pressures to each width size and tire. Further to that the tire construction has evolved from the time the sticker was put on your car. For sure everyone including Porsche wants to cover their butts on liability and the "safer" solution on the 285/30 under street conditions would be to keep it inflated and stiff. Is this the optimal though? You said you get over 8 PSI inflation driving the car! That usually happens only when you track the car! When the tires really get stressed and heated. Is it safe to run over 51PSI hot? Is it actually a safe and optimal pressure for handling and tire longevity? I just believe from experience that there are other ways to find that as well.
So what to do? Call the manufacturer of the tire and get a recommendation from them as well.
When i spoke to Michelin about my tire sizes they recommended that if I use it on the track to have max 36-38 PSI HOT! On the Street they recommended 36PSI all around for 911's.
Having said that, what you quoted on Tirerack is good and dandy as a general rule. What we are discussing here though is 993 specific. While you are absolutely correct that the Porsche sticker says 44PSI, I would say great, but use caution as my personal experiences on the track and off the track for the past 17 years that I own Porsche cars say that tire pressures are not always as black and white issue as you suggest relying on the sticker. I have had a brand new set of P-Zero's corded in 2 track days ( yes that is less than 500 miles) following Porsche's pressure recommendations on the rear to open my eyes to what I should be really doing...
I wish you luck driving at speed in France and Germany with more than 51 PSI hot. Truly...

geolab

Thanks for the instructive info Danny, I am going to take your recommendation seriously, I will take some puffs out of the tires before long highway trajectories.

ZombiePorsche44

I've always thought the Federal Interstate's were the American Autobahn. I sure drive em' that way!......LOL

ZP44

Jack of Hearts

Actually the question of what temps to run on various brands/sizes/wheels is always interesting....so lets all stay calm. When I had Dunlops on my 17s and inflated them to the factory recc. they wore the centers excessively.

Then I got PS ribs (still on the 17s) and backed off the pressures from factory but found the car wandered on the straights---settled, IIRC, at about 2 psi below factory recc.

Now I have PS-2s on 18" hollows (not N-rated for 993 ) and honestly can't remember where I have them set. I'll check tonight. Definitely below factory though. And by far the best tire I've tried so far.

porscheralph

OK - now to steal this thread a little - what about tires using nitrogen instead of air? My understanding is that nitrogen's coefficient of expansion is much lower then air and that even at high temps (say at 70-90 mph for extended periods) the increase in tire pressure is less then 1 psi. Anyone with experience care to respond?

Bull

Nitrogen and air, both being a gas, will expand/heat similarly. The difference is the amount of water vapor usually found in each. To switch to Nitrogen, you must find a way to completely evacuate the air from the tire in order to get max benefit from an expansion/heat impact, which is not an easy thing to do.

Most people who use Nitrogen in tires for the track do so because they have the Nitrogen for driving their pneumatic tools, so it is convenient for tire infaltion.