Part 1 Winter Tech: Tires

As we head towards winter, we all need to be thinking about preparing our Porsche’s for either winter driving or hibernation (that is, unless you’re taking it with you to Arizona). Over the next few months in the Tech Blog, we will discuss winter related topics, much of it pulled from our previous ORPCA winter tech session titled “Fun With Old Man Winter.”
Our first topic will be winter tires. There is plenty of information on this topic, so we’ll just focus on some key highlights.

If you’ll be driving your Porsche this winter season, do you really need winter-specific tires? If your tires are bald 10 year-old summer tires, then you certainly should not be driving any further on them due to their expiration, winter or not. If you will be headed into the mountain passes, then you’ll definitely want to use winter-rated tires for extra safety and security. If you’ll be staying in the Portland/Vancouver metro area only, it’s worthwhile to seriously consider winter tires this season. While it’s great to have the luxury of staying off the roads when it’s snowing, it’s even better to have the freedom of movement that winter tires provide. As we’ve seen in previous years, how do you know where you will be when a winter storm hits–maybe at home, at work, or out of town visiting relatives for the holidays. And who ever had an emergency that they could schedule around the weather? Bottom line, is it worth gambling with the safety of your vehicle, yourself and others, especially when your collision deductible and future insurance premiums are on the table?
We all know that tires are a compromise. One tire can’t be the fastest on the track, most controllable in the snow, and longest wearing. The ultra-high-performance summer tire that grips the track is incompetent as its tread compound becomes like “hard plastic” at below 32°F. Specific winter tires deliver much better slush, snow and ice performance than summer or all-season tires because their tread designs/compounds are engineered to master those colder temps and winter conditions. How do they do this? New winter tires begin with deeper tread depths and more open tread designs, and they also feature softer tread compounds that remain pliable in extreme cold temperatures. Keep in mind that while the extra tread depth and softer compounds allow new winter tires to provide more traction in deep snow, it also contributes to more tread squirm and drivers may notice a reduction in handling responsiveness. A recommended 3-5psi increase in inflation pressures increase tire stability and help offset the reduction in responsiveness.

Are 2 winter tires enough, or should you use 4? Nearly every tire manufacturer recommends four winter tires be used on rear wheel, four wheel/all-wheel, and/or front wheel drive vehicles. This is because if you use two dissimilar types of tires on your vehicle, you’ll have a vehicle that has a “split” personality. One end of the vehicle won’t react and perform the same as the other in the dry, wet, slush and snow conditions you may encounter before the end of winter. Especially in emergency situations, you’ll find that your vehicle will probably understeer in one condition and oversteer in another. By installing four winter tires, you maintain the most balanced and controlled handling possible in all winter driving conditions.

Should you use the same sized tires as you do for your summer or all-season tires? Actually no, as a wide and low-profile tire has to “plow” a wider path through snow which causes more resistance. The narrower the tire, the easier you can get through snow. So, if you have the option of going with a narrower/taller tire, this would be preferred.

As they say, until next time, keep the shiny side up and the (winter) rubber side down.

Jeremy Williams is the Oregon PCA Technical editor. He co-owns Matrix Integrated Inc. (Matrix Integrated Inc.) with his brother Justin. Jeremy can be reached at [email protected]