Can I leave winter tires on all year round?

Tire guy John Mahler answers readers' tire questions for Wheels.


Q: I’ve found that using good winter tires all year round seems to be cheaper and more convenient than switching tires over twice a year. They don’t wear that much faster, I don’t have to find a place to store the unused tires, and I’m not tying up a couple of thousand dollars of tires not being used. So far, it works for me.



A: In an ideal world where we all followed the rules this would be an OK idea. You are not the only one doing this, which is why tire companies are designing new tires called, “All-weather Tires.” This class of tires wears the Transport Canada mountain snowflake pictogram, but these tires can be left on the car all year round. At present several companies, have these: Yokohama, Nokian, Hankook, Vredestein and Goodyear come to mind.



There are several reasons the tire companies do not want you using their dedicated winter tires in the summer. Primary among these reasons is that winter tires do not like heat, by that I mean heat generated by underinflation. Underinflation heat can cause a tire to blowout and that can lead to dire consequences. They want you alive and well to come buy more tires.



And, one more important thing about heat, performance (grip) gets lower as the air seasonal ambient air temperature rises. Lower performance means less grip. On a day-to-day basis, very few drivers use the entire tire’s available grip. So who cares if we have less grip to work with? The day when you need an emergency stop may be the day you wish for more grip. Sometimes a car length shorter stopping distance can mean the difference between a big crunch or an almost impact.



So let us say, you check your pressures and maintain them religiously. Then we run into wear issues. A winter tire on summer roads wears faster than an all-season tire, just as the all-season tire wears quicker in winter than a winter tire. A study of Swiss drivers, by their equivalent of the CAA, showed that switching tires every season is actually cheaper at the five-year mark than using one set all year round.



I would not use Blizzaks all year round. Any of these tires whose model number starts with a “W”is a multicellular compound. When these tires are at 40% tread depth they become an all-season tire and can no longer be used in the winter.



Overall tire wear due to mileage is not the major concern; it is wear to the edges of the tread blocks that is the concern. Sharp edges on the blocks are what give good snow grip. Winter tires run in the summer usually show worn tread block edges. This is probably due to the fact we drive differently in the summer, higher speeds, higher cornering loads, and just generally making the tires work harder by dragging them across the pavement with higher slip angles.



All that having been said, if you check pressures regularly, and do not mind the higher wear rate you can run them all year. I know of a vice-president at a major tire company who did that all last summer, not by design, it just happened he kept forgetting to change over - too busy at work. One last caveat, if I were doing this, I would consider using an H-speed rated tire. It will be considerable more robust than the lower ratings.



Q I purchased a used car that utilizes Nitrogen in its tires. I have a problem in that there are limited places in my area that carry nitrogen for tires. Can I have my dealer just replace the nitrogen with compressed air without any problem to my tires? I am a normal driver that really has no application for nitrogen, it just happened to come with the car.



A Do not worry about mixing nitrogen with regular compressed air. I would not go to the trouble of having the dealer change out the nitrogen for regular compressed air. Just add air to the tires as required. The two live happily together. The normal atmospheric air is composed of 78.08% nitrogen anyway, so the two gasses will merge.



Got a tire question? Write to John Mahler at www.johnmahler.webs.com
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