RE: hydroplaning

["Derek van Veen" <derek@xxxxxxxxxxxxxx>]

> Date: Sun, 17 Oct 1999 23:08:51 -0400
> From: "WM" <molux@domain.elided>
You should probably be (a) running the same tires front and rear, 
and (b) replacing them all at the same time.  Always buy tires in
sets of four (like snow tires).  Remember:  two for power and two
for steering.

BMW's have wider wheels than most standard cars (6.5-7" as opposed
to 5.5-6").  Wider wheels / tires are great when it is dry, but in
the wet, they act like a boat keel.  More surface area means more
ability to float on water.  If you go for a really agressive tread
with lots of rubber on the road, you have even more surface area.

I've had decent luck with the Pirelli P4000 SuperTouring in Seattle
(where rain is not just an occurance, it's a way of life).  It's not
the greatest tire when it comes to dry handling, but it performs well
enough in the wet.  If you are really worried about it, find some old
cheap wheels (steel or bottlecap alloy) for your car and put the wet
weather tires on the cheapies and save the alloys for the high-performance
dry tires.

- -Derek
 '86 325es (totalled--soon to be taken from me)
 '90 325is (new car!)


> Subject: Hydroplaning
> 
> I have a '91 e30 with new Michelin MXV4's on the front, and 
> some slightly
> less new Goodyear Eagle HP's on the rear.  Driving home on 
> the Jersey Tpk in
> moderately heavy rain, felt slight loss of control once, and 
> took it easy
> for the rest of the trip.  I was being passed by many other cars, with
> inferior rubber and reputations.  What is the deal with 
> hydroplaning and
> safety in the rain?  In dry conditions, I feel untouchable in the car.
> 
> A few months ago, I was on the same road with much heavier 
> rain, and with
> the HP's up front, mounted incorrectly vis a vis the 
> direction of rotation,
> and some older HP's with about 3/32" tread on the rear.  At 
> about 55 mph,
> felt a shudder, and I decelerated to about 45 mph.  20 
> seconds later I was
> spinning around in place and then vectored off the hwy onto 
> the shoulder.
> Busted tie rod and banged up lower skirt/fog lamps/oil cooler.  More
> importantly, lost confidence in the car in the rain.
> 
> Where can I find out more about the situation?  Any recommendations on
> driving schools to teach techniques for safer driving in 
> tough conditions?
> I felt worried driving slower than the flow of traffic.
> 
> From an earlier post, a respondent wrote that the problem was 
> solely the
> fault of the low tread in the rear, and that the new tires 
> should have been
> on the rear, not the front, and that the incorrect directionality was
> irrelevant.  What's the real deal, scoop?

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