Tech Tips Tires for Your Porsche

by scott mcilvain

Question: What is the most important component on your Porsche? As you read from the title of this article, it is TIRES! Everything your Porsche does is transmitted through the tires to the road. The wrong or worn tires can dramatically affect how your Porsche drives.

Tires have come a long way over the past hundred years. Today’s tire and performance-vehicle manufacturers spend billions of dollars engineering the highest performing and safest tires for our cars. From the 356 to the 991, the right set of tires can be all the difference.

Let’s start with the basics on how to read a tire’s sidewall. If you have never looked at the sidewall of a tire, all the letters and numbers can be confusing. With the help of this illustration, I will point out some important information.

Another helpful marking on the tire is the date stamp showing when the tire was manufactured. The date stamp is after the DOT compliance number. This date stamp is four digits with the first two numbers the week and the last two the year.

As you can see in this photo, this tire was manufactured 24th week of 2004. Tires will age even if they are not used, so Porsche recommends replacing tires that are more than four years old. Any time you are looking to buy a used Porsche, it is good to check this date stamp to see if the tires need to be replaced.

Tire size (225/50R 16) has three main measurements. The first number is the tread width in millimeters. The larger the number, the wider the tire is. The second number is the tire aspect ratio. This number is the ratio between the side wall and the tread width. A 50 aspect ratio is twice as wide as it is high. The last number is the tire and wheel diameter. The tire and wheel MUST have the same diameter!

Porsche sports cars will wear tires differently from other passenger cars and trucks. Because Porsche cars have performance alignments, the inside of the tire will wear faster than the outside. It is important to check the inside of the tire for wear, not just the outside. A misaligned car or incorrect tire pressure will cause wear and drastically decrease the life of a tire. Cold tire pressure is one of the most important things to check on your Porsche weekly. Newer Porsches will have the recommended tire pressures on a badge somewhere on the car. For earlier cars, you should check the owner’s manual. As temperature changes, so will tire pressure (10 degrees=1 PSI change), so be sure to check tire pressure often because there can be a nine PSI difference through the seasons.

I have had many customers ask me for advice about what tires to purchase. I always recommend N-spec tires. Porsche engineers work with different tire manufactures to engineer specific tire attributes that include wet and dry grip, top speed, noise, hydroplaning, handling requirements, high speed durability and serviceability. If the manufacturer can meet or exceed these requirements, then the tire is designated an N-spec tire and can be fitted to a Porsche. There are different N-spec numbers. Zero is the first in the evolution of the tire; four is the latest. You must always match the N-spec to the same number when getting new tires. You NEVER want to have mismatched tires with two tires being different types. This will cause a handling imbalance between the front and rear of the car and is very unsafe! For more info on N-spec tires and a detailed list of N-spec tires, please visit Porsche’s website, http://www.porsche. com/usa/accessoriesandservices/porscheservice/ documentsanddownloads/.

Tires for the Track

If you are new to the track or are still a novice, it is recommended that you use street tires. The reasoning behind this is that street tires are more forgiving and predicable than race tires. I have had students in the past start on race tires and it set them back in the long run. For someone in DE 3 or 4 I recommend starting on a DOT R tire before moving to a full competition tire. A DOT R tire is still legal to drive on the street but will give great grip. They will wear very fast if driven on the street, so it is best to have two sets of wheels and tires. Whatever track-day tire you choose, make sure to have them heat cycled or heat cycle them yourself. Heat cycling is where the tire is brought up to operating temperature and then allowed to fully cool down. This helps the tire last much longer and provide even wear. Just like street tires, make sure to check tire pressure and alignment to get the maximum performance and longevity out of the tire.

For more information on tires, visit tirerack.com where most every detail of tires is explained and there are great reviews on most tires in production.