On Tue, 23 Nov 2010 21:49:14 +0000, santiago wrote:

do they make a difference?

Yes. Though how much depends on what tread pattern your existing
tyres have. If you have some form of "go faster" tyre with just
grooves and blocks with few or far between sipes (narrow slits across
block faces) then putting proper winter tyres on will be a
relevation. If you have an all weather or all season tyre you'll
still get a noticeable improvement in traction. If you have a M+S
(Mud and Snow) tyre winter ones are better but probably not enough to
justify the cost for a full set. You really should swap them as a
full set as well, having differing levels of grip front back is just
asking for the handling to get "interesting" just when you don't want
it to.

I speak from experience of Pirelli Scorpion ST and STR, (an all
season M+S type), Hankook Ventus ST (a "go faster" type) and
Vredestein Wintrac 4 Extreme (winter type) all on a Disco II.

The Hankooks are useless on snow and are noticeably different, as in
less grip, in the cold (5C) and wet. TBH they ain't much cop on
anything that is at all slippy, thin layer of mud or anything smooth
and wet.

The Pirellis are pretty good on snow and perform the same hot, cold,
wet or dry. Good all round road tyre with some gentle off road.

The Vredesteins are better than the Pirellis on snow and just as good
if not a bit better in the cold and wet. Can't comment on the summer
as I took 'em off at then end of March and I've only just put them
back on. If I'd been on Pirellis this time last year I'm not sure I
would have spent the £550+ on a set of Vredestiens, I was on the
Hankooks though and knew they where crap from the previous winter...

Of course living at 1400' on the North Pennines and almost guaranteed
a few days with several inches of snow or in the case of last year a
couple of months with several feet means that winter tyres are much
more of a requirement compared to people further south and/or at
lower levels.

Winter tyres are a softer compound and wear quite quickly. I did
6,000 miles last winter on the Vredestiens. I've just had to buy a
new one as one picked up a huge lump of ali that penetrated right
through the tread to the wires. The new one has 9mm of tread, so 9-2
= 7mm of useable tread before they become close to illegal. The old
tyres have worn by 2mm in those 6000 miles so I'm only going to get
about 20,000 miles from 'em. Pirelli STRs gave me over 30,000. The
Hankooks were on the car when I got it they have done 30,000 miles
with me driving but are now down to 2-3mm so more or less at end of
life.

And even with winter tyres you still need to know how to drive on
snow, a spinning wheel has sod all grip no matter what the type of
tyre is fitted.

--
Cheers Dave.
Nr Garrigill, Cumbria. 421m ASL.