bump for the % and effeciency of tyre tread, as opposed to the actual width of the rubber.
I only have 235's at the back, and the car is happy going thru puddles at any speed when the tread is new and deep. Because of the camber at the back my insides wear much faster, and when the inside half of the rear tread gets past the minimum tread depth as indicated by the markers, then it aquaplanes and squirms and jiggles like crazy over ANY standing water, even driving over a light stream of sidewash (water flowing across the road due to surface camber etc) makes the car jerk disturbingly to the left and right at the rear as the wheels at the back become unsettled at anything approaching 90kph over this water.
My brother tells me that its the HICAS going crazy because its wet, but I slap him on the head and point out that as each wheel at the back lifts up (They hardly ever both lift at the same time) the toe-in on each side will push the car towards the aquaplaning side, then vice versa as the water is traversed.
At freeway speeds its enough to make the car lurch suddenly and shoot half into the next lane over and is as scary as heck.
I have had my R33 for over 7 years and this is FACT, dont argue.
Any tyre will plane if you hit enough water at a speed that wont let the water flow outwards and away from the tyre. If you mount directional wet tyres the wrong way around you are actually channeling the water into the center of the tread where it will bottleneck and start to lift the tyre, something you could deftinatly do without.
Similarly, If your tread has a poor footprint (sides worn like mine) then the tyre becomes less and less effective as the flow patterns stop working properly.
Think physics people!