htc***
03-03-2010, 04:02 PM
That mean if al season tire is 205/50R17, then down size for winter use is 195/55R17 or 195/55R16 or which one is the down size 205/50R17? Just have a curious question to ask.
http://autos.sympatico.ca/winter-driving/1898/winter-tire-decoder
What you need:
Whether you get snow where you live or not you need winter tires. All-season tires are a complete misnomer as they are intended for all the seasons of Florida or San Diego, not Toronto and Montreal. And it’s not just a matter of traction in deep snow or on ice, for which M+S and specific ice traction tires (like Bridgestone’s Blizzak tire) are ideal. The simple fact that it’s below freezing means you need winter tires as all-seasons and high-performance tires actually freeze up (their Glass Point) and loose most their traction even on dry surfaces.
It’s also important to note that you need winter tires even if you have an AWD or 4WD vehicle. Getting going is only part of the equation. In order to be able to stop safely and turn confidently you need winter tires for their low temperature compound and enhanced winter driving characteristics.
By the same token it’s very important to get your winter tires off your car as soon as temperatures increase. The soft compound of a winter tire won’t last long in warmer temperatures, not to mention they offer significantly reduced traction and handling in warmer weather.
What the numbers mean:
With the exception of Michelin’s PAX tires (which you’re not likely to ever run into unless you buy a Bugatti or live in Europe) the sizing of tires is universal. If you get down on your hands and knees you'll see a series of numbers like this 195/65R16 89T on your average family sedan or maybe 295/35R19 98Y on your sexy two-seat mid-life-crisis-mobile.
In either case the first three digits are the width of the tire. In the example above the tires are 195 and 295 mm wide, respectively. The next number is a bit more abstract. It’s the ratio of tread width (195 and 295 in this example) to sidewall height. The lower the number, the shorter the sidewall but it's relative to width. Shorter sidewalls not only look cool but increase maximum grip and transitional response…that’s why high-performance cars typically run the shortest sidewalls they can without completely obliterating ride quality.
The last two digits are the wheel size. Sixteen and nineteen inches here. The “R” refers to radial construction. The next two digits refer to load rating and the final letter is a speed rating. “S” is up to 180 km/h, “V” 240 km/h, “Y” is 300km/h and so on. Most snow tires are speed rated “T” or “Q” (160 km/h and 190km/h) which is plenty for inclement weather.
All the sizing information applies to winter tires just as it does for all-seasons and summer tires. When switching to winter tires, however, many manufacturers recommend that you go one size narrower and, therefore, increase the sidewall ratio in order to maintain the overall tire diameter. Follow?
So, if you have 195/65R16 all-seasons on your car you would be well advised to select 185/70R16s for winter use. The narrower tread will dig into snow better and there's the added bonus of narrower sizes with higher aspect ratios being less expensive as well.
You can mount winter tires on steel wheels or alloys but open desings with thin spokes aren't ideal as snow can build up inside the wheel rim and cause highs-speed vibration due to imbalance.
Winter tire identifiers:
In your quest for winter rubber you’ll come across the M+S designation. This is for tires that are designed to perform especially well in the snow, perhaps sacrificing more dry performance than some other winter tires. An icon of a mountain with a snow flake set into means a tire is designed for maximum winter traction.
http://autos.sympatico.ca/winter-driving/1898/winter-tire-decoder
What you need:
Whether you get snow where you live or not you need winter tires. All-season tires are a complete misnomer as they are intended for all the seasons of Florida or San Diego, not Toronto and Montreal. And it’s not just a matter of traction in deep snow or on ice, for which M+S and specific ice traction tires (like Bridgestone’s Blizzak tire) are ideal. The simple fact that it’s below freezing means you need winter tires as all-seasons and high-performance tires actually freeze up (their Glass Point) and loose most their traction even on dry surfaces.
It’s also important to note that you need winter tires even if you have an AWD or 4WD vehicle. Getting going is only part of the equation. In order to be able to stop safely and turn confidently you need winter tires for their low temperature compound and enhanced winter driving characteristics.
By the same token it’s very important to get your winter tires off your car as soon as temperatures increase. The soft compound of a winter tire won’t last long in warmer temperatures, not to mention they offer significantly reduced traction and handling in warmer weather.
What the numbers mean:
With the exception of Michelin’s PAX tires (which you’re not likely to ever run into unless you buy a Bugatti or live in Europe) the sizing of tires is universal. If you get down on your hands and knees you'll see a series of numbers like this 195/65R16 89T on your average family sedan or maybe 295/35R19 98Y on your sexy two-seat mid-life-crisis-mobile.
In either case the first three digits are the width of the tire. In the example above the tires are 195 and 295 mm wide, respectively. The next number is a bit more abstract. It’s the ratio of tread width (195 and 295 in this example) to sidewall height. The lower the number, the shorter the sidewall but it's relative to width. Shorter sidewalls not only look cool but increase maximum grip and transitional response…that’s why high-performance cars typically run the shortest sidewalls they can without completely obliterating ride quality.
The last two digits are the wheel size. Sixteen and nineteen inches here. The “R” refers to radial construction. The next two digits refer to load rating and the final letter is a speed rating. “S” is up to 180 km/h, “V” 240 km/h, “Y” is 300km/h and so on. Most snow tires are speed rated “T” or “Q” (160 km/h and 190km/h) which is plenty for inclement weather.
All the sizing information applies to winter tires just as it does for all-seasons and summer tires. When switching to winter tires, however, many manufacturers recommend that you go one size narrower and, therefore, increase the sidewall ratio in order to maintain the overall tire diameter. Follow?
So, if you have 195/65R16 all-seasons on your car you would be well advised to select 185/70R16s for winter use. The narrower tread will dig into snow better and there's the added bonus of narrower sizes with higher aspect ratios being less expensive as well.
You can mount winter tires on steel wheels or alloys but open desings with thin spokes aren't ideal as snow can build up inside the wheel rim and cause highs-speed vibration due to imbalance.
Winter tire identifiers:
In your quest for winter rubber you’ll come across the M+S designation. This is for tires that are designed to perform especially well in the snow, perhaps sacrificing more dry performance than some other winter tires. An icon of a mountain with a snow flake set into means a tire is designed for maximum winter traction.