Tires






TIRES


Think of a finely tuned athlete.  Would you expect him to break a world record wearing wing tips?  It has been said that all the components in your expensive sports car are there to accomplish one thing.  That one thing is to make the tires work better.  Want a quicker lap time?  The biggest difference you can make is improving your tires.

So why do we continually see owners trying to short-cut the tire buying process?  Owners will risk thousands of dollars in body shop bills trying to get another hundred miles out of worn tires.  When the grooves that channel water begin to disappear, it is time to replace the tires.  The wear bars indicate an absolute minimum tread depth for wear, but realistically your performance tires should be replaced well before they reach this point.

Bending over to inspect tires may seem like a hardship, but the consequences of not doing so are far worse.  First time Porsche owners may not realize that the rear tires may wear at up to double the rate of front tires.  Owners coming out of passenger cars may expect thirty or forty thousand miles, but this won?t be the case with a Porsche.  Your right foot on the accelerator is directly related to the amount of tire wear you can expect. 

When the 993's were introduced, they had a touch too much negative camber dialed in.  Mike Hardage, to the best of my knowledge, holds the record for going through a set of rears: 1,900 miles.  Typically, 12,000 to 15,000 miles is common for rears.  Watch them, and don't push your luck.

The frozen tundra has shed a new light on tires for me.  I wasn't aware that temperatures under 45 degrees Fahrenheit will pretty much render performance tires ineffective.  Performance tires are designed to stick to the road.  As the rubber gets colder, it gets harder and less sticky.  Conversely, winter tires are horrible in warm weather performance situations.  All-weather tires are neither fish nor foul.  They are not particularly good in either extreme; they are adequate for both.  One exception to this rule is the Bridgestone RE960AS Pole Position.  These tires have put up amazing performance numbers and got me through a Chicago winter okay.  Cayenne owners are cheating themselves out of the some of the pure performance built into that vehicle because they don't want to be bothered with changing tires or paying for an extra set of wheels and tires.

The "N" designation means that Porsche has tested and approved this tire for use with your Porsche.  Porsche's main concern is the amount of adhesion the tire generates and has a narrow window for the exact qualities they desire.  These tires need to be consistent and compatible with computer controlled systems like ABS and PSM.  These are non- adaptive systems and require a given amount of grip as determined by Porsche.  In years gone by, the main concern was simply the speed rating.  This does not mean that non-approved tires are inherently inferior; it just means Porsche has either not tested or rejected the tire based on one of the parameters.  A potential problem in selecting a non-"N" rated tire is our litigious society.  A lawyer could question the safety of a tire not approved by the manufacturer.

The response from Bridgestone on the prudence of selecting non-N rated tires for your Porsche is in your owner's manual which states, "If you do not use an "N" rated tire, make sure it comes from a reputable dealer.? 

I know you don't want to hear the "F" word, but the Enzo uses the RE050 as standard fitment.  Obviously, either tire would suffice.  Maybe sizing and availability should be the determining factors.

The Tire Rack has conducted its own tests and favors the new RE050A Pole Position over the S03 and over the Michelin Pilot II in the wet. 

Both manufacturers have new dry handling tires: the Michelin Cup tire and the Bridgestone RE11.  The Michelin has a wear index of 80 while the Bridgestone has a wear index of 180.  It also appears that the same would hold true here with a slight edge to Michelin in the dry and Bridgestone in the wet.  I am a strong supporter of wet performance over dry, as this is where most drivers need the assistance.  The differences in performance numbers also tend to be greater in the wet.

Tire pressure is critical to performance, safety, fuel economy, and wear.  Factory specs are an excellent choice for the street.  At the track, lowering the air pressure will increase stick.  Five or six pounds will increase your contact patch, and remember you are dealing with much higher temperatures.  Beware the law of diminishing returns.  Too little pressure may cause the bead between the wheel and tire to fail (not advised).

Neglecting your tire pressure is not good.  I have found nails in my tires after checking the pressure.  The act of checking did not cause the nail to be there.  What would that have done if I went out and pushed the car?  Preventive maintenance is recommended.  It is normal for a tire to lose one pound of pressure per month without doing anything abnormal.  In twelve months you could be down twelve pounds of pressure.  Well, it was fine the last time it was checked.

Tire wear is probably the opposite of what one would expect.  Excess wear in the middle of a tire is a sign of under not over inflation.  Radials spin high in the middle when under inflated.  Higher pressure will deliver better fuel economy (less rolling resistance), and longer tread life.  Again beware the law of diminishing returns; too much inflation can create its own problems.

When replacing only two tires, stick with the same brand, model and ?N? designation as found on the fronts.  Never mix tires.  The choice is whether or not to replace all four at once.  Should you choose, either sticking with the originals, or going with a new set of Bridgestones, you will be safer and happier with your Porsche.  Just as there is no substitute for your Porsche, there is no substitute for a great set of performance tires.

Saving a hundred dollars by going to a cheaper tire is insane.  Why buy a performance car and go with the wing tips?  Concerned about being ripped off?  Most any automobile magazine will have a "Tire Rack" advertisement with sizes and prices clearly displayed.  These prices are usually as good as it gets.  The Ozark Tour participants now can use Roadway Tire (www.roadwaywholesaletire.com ).  Be sure to indicate that you are with the Ozark Tour group.  At the dealerships be willing to pay a small, but fair mark up; and, by all means, have a Porsche technician do the installation.  You will pay more in labor, but those expensive wheels are at stake.

We believe that tires are the most important part of your Porsche.    We will recommend replacement whenever it is necessary.  This policy promotes safety and performance making your ownership experience better. 

While there have only been a few incidents over the past twenty some years on the Ozark tour, the majority can be directly related to tires.  This is one area where there is no compromise.  Spend the money and reap the rewards.

A few years ago, the Ozark tour included Bridgestone's performance expert, David Sheldon.  He brought up something that I had never thought of: recovery.  Tires will break loose at their limit.  Some tires are easily reeled back in while others, notably the Pirellis, stick well to a high limit, but when they go; they are gone.  The bean-counter comparisons are great, but there are more factors that just won't show up on a spread sheet.

Bridgestone has been on top of their game for the past several years.  The only drawback is sizing.  It's impossible for a manufacturer to offer every conceivable size on every tire.  For most Porsche customers the RE050A Pole Position (soon to be replaced by the S04) would serve them best, but conditions and tastes may lean toward some of their other offerings.  The RE11 is a very aggressive tire with decent wear qualities.  Whatever tire you choose, the Bridgestone line up is on the cutting edge of technology and should give you a viable option.


 
Read more from the "Just Jack" article base
 
 Braking  Breaking in your new Porsche
 Dealing with the
 Driving Position
 Gasoline  Literal Translation
 Oil type and Weight
 Pavement 
 Performance Driving 101
 Road Rash
 Radar Basics
 Shifting 
 Tires  What separates you from impending doom
 Your worst nightmare has just come true
 Red Mist
 Fatigue Got to go right now!
 Dynamic Cornering Lights
 Literal Translation
 Next Generation 911/991, or Boxster Cayman/981
 


   

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