Re: best tyres up front or in the rear? (was '89 200q ?s)

[I6941tb@aol.com]

In a message dated 96-12-06 13:51:34 EST, foundation1@earthlink.net (Sargent
Schutt) writes:

> This being the case, the front tires recieve more downforce and
> are relatively less susceptible to hydroplaning under braking.
> The rears, being more susceptible to hydroplaning 
> (eg they lose ground contact before the fronts 
>  because they have less downforce on them) need more tread depth than the 
>  fronts to help disperse the water. The fronts have more 
>  wieght on them, which helps keep them on the ground. In the wet, it is 
>  better to compensate with the deeper tread in the rear to keep the back
>  from hydroplaning and subsequently swinging around and passing you. 

I have to disagree here. The front tyres are_more_succeptible to hydroplaning
because they take the impact of water first; they have to channel it away
through the grooves/push it away by their mass. The rears have a luxury of
following the fronts in the relatively dry "tracks", laid in the water by the
latter. This phenomenon is well described in the literature.
BTW, this observation prompted the advent of the famous Pirelli Assymetricos.

Subjectively speaking, every time that I hydroplaned, I had a very
distinctive feeling that the front tyres were loosing traction first and the
nose of the car started to wander. Horrendous understeer! I'd rather have the
car oversteer since it is much much easier to bring back. 

Also, if I had to choose between the definetely better braking ability of the
car (with better tyres in the front) and an alleged superior
traction/directional stability (with better tyres in the rear) I would
definetely choose better braking! Especially on a quattro. My car, shod with
205/55/ZR16 Dunlops SP8000, tracks like a proverbial train on rails and
requires a determined hand to make it loose grip wet or dry, but it brakes no
better than a regular mere mortal 2WD, so I'll take the best tyres in the
front anytime.

Besides, I have yet to see anyone putting better tyres in the rear on a
Q-club track event.

Igor Kessel
'89 200TQ