Can't really downgrade tires for Porsche Boxster S

Aug 16, 2008

Special to the Star

Q: I own a 2004 Porsche Boxster S. It is equipped with Michelin Pilot Sport tires, which have provided great traction, however the lifespan of the rear tires is troubling. I am not an overly aggressive driver and would be willing to sacrifice some performance for longer life provided it didn't overly affect handling.

The rear tires last an average of 14,000 to 15,000 km. The fronts manage a more tolerable lifespan. Are there any suggestions for alternative tires?

A: Alas, I have no good news for you. Since the Porsche Boxster S is a sports car, it is fitted with high-performance tires. It is rear-wheel drive, so the rear tires take more punishment. I would consider getting the alignment checked, to make sure it is not an issue. The Michelin Pilot Sport tires' wear rate is typical of that size of tire.

If you switched brands, you would need to buy four tires, so they all match. No matter what the brand, the wear rate would be similar. Tire companies do not make different types of compounds in the same size of tire, so there is no longer wearing compound out there. Certain sizes are fitted only on high-performance vehicles and so the manufacturer's focus on grip rather than tire life. The tires are "size engineered" for the vehicle they will fit.

Q: I have an opportunity to purchase an original set of wheels and Bridgestone tires for my 2007 CX-7 with only seven miles on them. They were removed from the owner's CX-7 in order to install 20-inch diameter wheels and tires. I would like to use the extra set of wheels to mount my snow tires. I was hoping to store the newly acquired Bridgestones to use when my current tires wear out.

I have read in your column that five years is about the maximum to expect with regard to tire life, regardless of mileage. Since the wheels will be in storage and not used, is there any way to extend the life of the rubber?

A: That is an interesting dilemma. Five years is about the average life expectancy for a tire, but there are no stats for stored tires. Michelin used to say 10 years was possible under ideal conditions. For maximum storage life keep the tires away from light and away from any electrical motors (which may generate ozone). So the furnace room for storage is out. Keep the tires cool but avoid freezing so an unheated garage is also out. I would keep them bagged. And most important, do not treat them with any kind of tire cleaning/shining product. Stack them on their sides and rotate them at least once a year. Before using them check for hairline cracks inside the tread area and in the sidewall area.

Q: I purchased my 2004 Buick LaSabre as a demo in the fall of 2004. It was wearing Michelin Symmetry tubeless all-season tires (P225/60R16 97S). I was told the tires needed to be replaced. Cost for tires, installation, alignment and balance was quoted at about $1,000.

Are these tires a better/best choice for this car? Also, how do I know if I am purchasing new (recently made) tires?

A: The Michelin Symmetry is a fine tire. However, the dealership is overcharging you a bit. These tires have a list price of $191 each. Most independent tire shops discount them at least 10 per cent and include a new valve, mounting and balancing the tires. So your cost for a set should be about $616 plus tax. An alignment would add about $100 to $150 to this cost.

You may also want to consider the Michelin HydroEdge. It is a newer design, has a longer treadlife and is far superior in the wet. A set of these would cost $738. They are well worth the extra money.

To tell a tire's age, check the numbers on the sidewall. You will find a string of letters and numbers like "DOT G6F1 675K 082007." The first two letters are the tire manufacturer and the plant code. The third and fourth letters are the code for the size of tire. The fifth to eighth letters identify the tire brand more specifically.

The rest of the numbers are what you want. These numbers are the week the tire was made and the last digits are the year. So in my example the tire was made during the eighth week of 2007.

Email tire questions to John Mahler

at thetireguy_1 @hotmail.com.

Please include vehicle's make, model and year, tire brand and size,

as well as your name, address and phone number. Volume of mail prevents us from answering all queries or providing personal replies.

Toronto Star