hydroplaning

[James Russell]

To my understanding of physics there are a number of reasons as to why
vehicles hydroplane.  Weight, tire width, speed, tire design, and weight
distribution all play roles in this.

Hydroplaning is when the tires rides on top of the water and not on the
road way itself. The more weight you have on a tire helps, it will be
harder to get a 5 inch wide tire to hydroplane on a 1 ton vehicle versus a
9 wide tire on the same 1 ton vehicle, this due to the weight being
dispersed across the width of the tire. The narrower tire will have more
weight per inch than the larger tire which has more inches to distribute
weight.

A heavier vehicle is harder to hydroplane, but with wide tires it could
have same affect as any other vehicle. I am guessing that there is weight
of vehicle to width of tire ratio in there somewhere.

Also certain tire designs help move water from underneath the treads of the
tires, like aquatreads or something.  The theory is that with special
channels water will move to these channels and not be trapped underneath
the tread causing the tire to ride on water.  I don't know how effective
these are at highway speeds or even at low speeds.

Another thing is the balance of the car, obviously the front tires are
going to hit the water first.  With some extra weight, like an engine, in
the front there is more weight on the front tires which will help with that
weight per inch thing.  Also when you are driving the "weight" of the
vehicle moves towards the rear, like when you are accelerating the nose of
the car move up.  Also the same theory when you are slowing down, the nose
dips and the "weight" of vehicle is on the front tires, this is why you see
racers tap their brakes before going into corners so that a little extra
weight is on the front tires so they can steer a bit better.

I am not surprised that your MR2 had difficulties with this.  #1 it is a
light car #2 mid engine #3 it is a sporty car so it might have wider tires
than comparable weight vehicles #4 the tire design might have also been a
factor.

I am sorry if this was too dummy down, I have no idea of your knowledge of
vehicles and traction and things of that matter.  I took a course at Bob
Bondurant High Performance Driving School, as a graduation gift, it was a
blast, plus a confidence boost!

Good luck, hope it all makes sense.

Brad Russell

1984 4ksq