Posted by moose on November 02, 1998 at 23:48:46:
In Reply to: Re: Bridgestone Potenza RE930 vs. BFGoodrich Comp T/A HR4-2 posted by Mark on September 02, 1998 at 18:06:31:
Stopping on ice We ran our ice-braking tests at a rink at
Connecticut College in New London. From 15 mph, our
stopping distances with the antilock brake system working
ranged from 42 feet for the Dunlops and Coopers to 61 feet for
the Firestone Firehawk touring tires; with the ABS disabled,
from 58 feet for the Dunlops, Yokohamas, and Coopers to 75
feet for the Firestone Firehawks.
-consumer reports
November 1998
Ratings Winter tires
Shopping strategy
You may not need winter tires in many parts of the U.S. Even in
many Northern areas, you may get by with conventional tires if snow
removal is prompt and you can wait until the roads are clear.
Who needs winter tires?
If you . . .
You should have . . .
are an emergency worker who has to
get through deep snow or slick
mountain roads . . .
a vehicle with four-wheel or all-wheel
drive and four winter tires, possibly
with chains.
drive regularly in the Snow Belt . . .
a vehicle with all-wheel or
front-wheel drive, or with rear-wheel
drive and traction control--and winter
tires.
drive regularly in moderate winter
conditions . . .
any car with winter tires.
drive occasionally in light winter
conditions . . .
any car with all-season tires.
What we tested. Seven winter tires, as well as one
touring-performance tire that had performed especially well in our
previous snow-traction tests.
Where to shop. Tire dealers generally have a knowledgeable sales
staff and a wide selection. Service stations typically offer a limited
stock and limited expertise. Car dealers generally have the smallest
selection at the highest prices. Warehouse clubs tend to offer
economy tires at economy prices; they're apt to have the least
knowledgeable sales staff. Mail-order houses generally offer the best
prices, a good selection, and a knowledgeable sales staff.
consumer reports
The tests behind the Ratings
We mounted each tire model, in a set of four, on a 1998 Mercury
Mystique LS. (Its tire size, 205/60R15, also fits many other compact
and midsized cars.) Overall Ratings for all-around performance
combine performance on wet and dry pavement and on ice and
snow. They also include ride comfort and noise evaluations. Overall
Ratings for snow/ice performance are based on three tests:
accelerating from 5 to 20 mph on level, packed natural snow;
climbing various grades on packed man-made and natural snow; and
braking on flat 20° F ice. Safety-related tests are weighted most
heavily. Braking tests were from 60 mph on dry pavement, 40 mph
on wet pavement, and 15 mph on ice. Some vehicles don't have an
antilock brake system (ABS), so we ran all our braking tests on wet
pavement and on ice with the ABS working and again with ABS
disabled. On dry pavement, hard braking without ABS would
damage the tires for further testing, so we did our dry-braking tests
only with the ABS working. Our average braking distances were: on
dry pavement, 154 feet; on wet pavement, with ABS, 84 feet; on
wet pavement, without ABS, 101 feet; on ice, with ABS, 48 feet; on
ice, without ABS, 63 feet. Cornering is a measure of grip in hard
turns. We used a skid pad with a 200-foot diameter--first wet, then
dry. Driving in a circle, we gradually increased our speed; an
accelerometer recorded the cornering force at which the tires began
to break away. Emergency handling simulates a situation such as a
child running into the road from between parked cars. Traffic cones
outline a course with abrupt turns to the left, right, and left again. The
more quickly and precisely we could negotiate the course without
knocking over any cones or spinning out of control, the better.
Hydroplaning is when the tires skim over the surface of standing
water and lose contact with the pavement below, resulting in loss of
steering control. We drove repeatedly through a mild curve over a
pool of water about 10 mm deep, increasing speed until the car
started to slip to the side. We evaluated ride comfort and noise on
both smooth and coarse roads. We judged noise objectively--with a
sound meter--and subjectively, and we incorporated both test results
in the overall score. Rolling resistance is a measure of how easily
the tires roll. From 40 mph, we coasted in neutral and recorded the
car's speed after rolling 2,100 feet. The higher the speed, the better
the fuel economy. The differences may not be great, but every little
bit helps. Price is the estimated average, based on a national survey.
The government requires most tires to carry a tread-wear rating on
their sidewall, but a loophole in the standard excludes winter tires.
We didn't test for tread wear.
Stopping on ice We ran our ice-braking tests at a rink at
Connecticut College in New London. From 15 mph, our
stopping distances with the antilock brake system working
ranged from 42 feet for the Dunlops and Coopers to 61 feet for
the Firestone Firehawk touring tires; with the ABS disabled,
from 58 feet for the Dunlops, Yokohamas, and Coopers to 75
feet for the Firestone Firehawks.
Overall Ratings Snow/ice performance
1 Yokohama Guardex 600
2 Dunlop Graspic HS-1
3 Michelin XM+S Alpin
4 Bridgestone Blizzak WS-15
5 Firestone Winterfire
6 Pirelli Winter Ice Asimmetrico
7 Cooper Weather-Master XGR
8 Firestone Firehawk Touring LH
Brand and model
Overall
score
Overall Ratings All-around performance
1 Michelin XM+S Alpin
2 Bridgestone Blizzak WS-15
3 Firestone Firehawk Touring LH
4 Pirelli Winter Ice Asimmetric
5 Firestone Winterfire
6 Dunlop Graspic HS-1
7 Yokohama Guardex 600
8 Cooper Weather-Master XGR