Tars

[PDQSHIP@aol.com]

In a message dated 95-11-29 15:45:10 EST, you write:

>
>I think what you are saying is that there is a critical trade off between
>weight and float. On lighter cars, the weight vs the sidewall stiffness is
so
>low that the aquaplane effects cannot be offset by the weight of the car. So
>it
>behooves one to go to a narrower tire. This does not effect stability or
>response to the same extent as say an Audi, because the absolute speeds are
>lower, the CoG is usually lower and one needs that weight to get tread
action
>vs the distortion in the heavier car.  I think you are also saying that
>changes
>of the order of 195/65 to 205/60 are clearly going to be beneficial. However
>if
>one went to say 245/45 (with a wheel change, and assuming clearance), there
>might be a loss of wet/winter traction for the same reasons that would
effect
>a
>much smaller change on our Coopers. Do I read you right?

Yessir.....
>
>
><<I refer to this as time delay syndrome.....  If you take your summer tires
>and go 60 mph, and do lane jumps quickly, you can eventually get the tire
>behind the steering input.....  If you do this with a higher sidewall summer
>tire you will notice that the tire falls almost a whole input behind the
>steering, that is the definition of tire float on sidewall......  A stiffer
>sidewall can "help" but not eliminate the problem, cuz it's just rubber and
>flexing steel belts after all, you have a height to weight problem.....>>
>
>I tried this exact exercise on a skid pan with the Coopers many moons ago
>using
>various sizes of Dunlop SP Rally tires, and you are quite right...in the
dry!
>Once we got the surface wet, the narrower sections did better than the wider
>tyres after a very small change. I dont remember how much they changed, but
>we
>went from 6" wheels to 7" and tested 4 sections on both 10" and 12" rims. In
>fact on the widest wheel/tyre combo, we were aquaplaning at 50 mph, and
>unable
>to do emergency brake turns any faster than 30 mph.

And my post will agree with you here, you can offset the narrow tires with a
wider rim, but I think if you had measured the "actual" footprint, there is a
small gain in width with a narrow tire on a wide rim.......  The tire tread
is more key than the width

>
>So bottom line, and back to Audi (so as not to bore the lurkers - G) I dont
>think that one can generalize about this, but i would not recommend wide
>section low profile snow tyres for quattros, irrespective of their fat
chops!
>Going from 195 to 205 wont hurt in all but the most marginal conditions, but
>any wider and I think that at slow speeds, you are compromising the quattro
>qualities.

And my testing of the audis in this regard will confirm this......  I had a
set of 215/60 snows that I compared (they came with my machine when I bought
it) back to back to a set of 205/60's and found that the difference was
BIG......  Conclusion, the 3000-4000lb weight class gives good performance on
a 205 width tire in adverse conditions.....  In the 2000 to  3000 I would
consider a 185/60 as the widest tire....  And sub 2200 or so I would consider
a 175 as the widest......  But I will also argue that unless ground clearance
is your priority, a 60 series for a snow will beat a taller snow for
control........  A truck or a hummmer or some such would benefit from a tall
tire cuz the track is usually wider, and there is really a wide suspension
tolerance of error before you get any handling effects.....
> I suggest that the tread
>pressure
>generated by my Goodyear Eagle M+S 185 section tyres benefitted me far more
>than I was hurt by sidewall float at some higher (later) speeds.
>
Would a 185/60 handle any worse? Would a 205 handle any worse?  I would argue
no to either question.....   a 185 is not a wide tire.......  neither is a
205 on a quattro with the weight......   I would argue that a 206/60 would
perform no differently than the 185 on the q' and I would look seriously at
tread pattern before the tread width (assuming your range in the snows at
175-205) ......   One of the best snows I've driven ( have had the vreds,
glavs, haka 9 & 10's, goodyear, goodrich, conticontacts ) was a crosscut
eagle VR.....    Look closely at the gatorback, a tread design that is going
on 10years old, most of the best performing tires copy that tread still
today, M&S, dry or wet....  Really want an interesting snow, I have a Pro
Rally buddy that mounts VR's backwards in the winter, and they are awesome in
snow.......  

I don't argue that there are some awesome snow tires on the market that
outperform others (my P210 included) in the snow.......  But to me, snow is
NOT the majority of all but 10% of the driving most of us do on them......
 But the hoka's ride like a truck, and handle the car like one, so do the
vreds and the glavs.......  And that is with a weak sidewall that floats in a
major way........  Tall, I don't take that argument for a minute, that extra
inch can make a heavy car just unruly in any conditions.......   a 185/70 vs
a 185/60, take the 60, the control is better, looking for ground clearance,
fine, but that is the only advantage......  

I appeal to the understand what and why you are doing what you are doing when
buying snows......  If the majority of your driving (and mine is in chicago
and Northern Michigan) is in the wet and slush, a bonzai hoka 10 is major
overkill......  a Eagle vr could out perform it in all but the worst of
conditions (BTDT), and even then, you will only notice the difference at the
performance level of driving, not point a to b stuff.....  Going ProRallying,
we can talk, there are some great tires that can be cut to be the most
awesome of snows.....  You explain the reasoning to the others in the car
tho.....   

Scott