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Vans & Minivans Mazda MPV Mazda MPV: Problems & Solutions 
4469 messages, Last post on Oct 27, 2006 at 8:04 PM
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I haven't heard this must discussion about physics since high school! Don't know how I ever made it throught that class ... "Mr. Carter are you sleeping again?" - "No sir, I was trying to determine the coefficient of drag of my eyelids against my eyes"!
Hydroplaning? Just get a set of X-Ones for your MPV and plow right on thru the puddles! BTW, I'm still looking for a nice 16" alloy set for the van. When I find them, I'm going to take the almost new 15" X-Ones off the van and put them on my Accord. Yes, they will be wider than the current MXV4+ on the Accord (205 vs. 195), but the tread patterns between the two tires are drastically different. If you've never seen their tread pattern before, check them out X-Ones
I'll have to admit though that I've given a more-than-cursory glance at the Dunlop SP Sport A2 Welcome back Prof. Tboner! Trying to make up for lost time, er, posts? ...hehe. Could you share your Dunlop experiences again with me? I'd appreciate it! |
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SP5000's, all asymetrical. The MPV and the Buick both wear the 225/55-16 size, and I've all but destroyed a set of 205/55-16's on the SVT Contour. I really like Dunlop as a budget minded performance tire. The only really bad experience I've had was I thought the SP4000's wore out too quickly. It looks like the Buick will get about 30K enthusiastic miles on them. I suspect I can get 25K or so on the van. Michelin makes a good tire as well. Very consistent quality. I have the Sears equivalent of the RainForce® MX4, the Weatherwise on the Buick during the winter. They are good enough for winters here, but go to where they really get snow, and you'ld probably suffer. And since Sears is very convenient to my home, and those rotations are not so painful while I cruise the mall ... Going back to Dunlops, I've had the D60's on other cars in the past and felt they were a good tire. Personally, between the X-One and the A2, I'd pick the Dunlop A2's because the traction and temp ratings are more favorable. I've never been a fan of tires that can go 100K miles. TB |
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| Yup, that's why I'm looking at the 'Lops. Better priced than the Mich's, H-rated vs. T-rated, and more of a performance tire. Their hydro-resistance rating is equally as high according to Tire Rack. That is one of my predominant factors in choosing tires, but I also want the other good stuff too. Darn, I'm hard to please! Oh yeah, "the look", my d/w is a very VERBAL person - she learned years ago that I ignore the look ;-( | |
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Here's my $0.02. Whether hydroplaning will occur depends both on the ability of the tire to push water out of the way (related to contact pressure in turn related to vehicle weight and tire size) and the time over which water can be pushed out of the way (related to tire size). Given equal "contact pressure," I think a larger tire would hydroplane more easily than a smaller tire since the water would have to be moved further to clear the contact area - only if the two tires had no tread! (I.e., the water must be pushed the full width of the tire in order to avoid hydroplaning.) But given that we're usually dealing with intact tread on good tires, the situation changes. Water only has to be moved a distance equal to the separation of the grooves so it's not obvious, to me at least, that one size has any intrinsic advantage over the other. The key here is "equal pressure." Generally, you put larger tires on heavier vehicles to support the greater weight and the contact pressures turn out to be roughly the same. Also, tread design matters. My point? The physics isn't all that simple! tidester Host SUVs; Aftermarket & Accessories |
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For those who haven't met Tidester over in SUVs or A&A, he's been known to teach a few math classes now and then. He likes this sort of stuff! (notice that you didn't see me hopping in this thread?). Thanks, partner! Steve Host SUVs, Vans and Aftermarket & Accessories Message Boards |
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Ruh-roh, big guns brought in to discuss hydroplaning, lol. Good to see you Tidester! Mls64, my general rule of thumb when bleeding brakes is to start with the corner farthest from the reservior, so that'd usually means the right rear, then left rear, right front, then left front. /j |
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| I imagine that ones that are worn out and soft would tend to give way more easily to the water's upward pressure and hydro, no? | |
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It is quite simple to understand why a car can hydroplane. When tires cut through water, before they come in contact with pavement, they have to force the water off the track. The actual amount of water thrown away and the speed at which it is pushed determines the force that is put on it (and as a result, the wheel feels the same amount of force back). To determine the mass of water that is pumped out of wheel's path, we need to get the puddle depth, tire width and track length, multiply all those and multiply by the density of water. For example, 215 mm wide tire going through 10 mm deep and 2 meter long puddle would need to cut through about 4.3 kg of water. A car traveling at about 100 km/h would cross that puddle in about 0.07 second. Given that the car has 4 tires, it means that it will throw away about 240 kg of water per second. Of course, we don't know the speed at which the water comes from under the tire. But assuming, that 205 mm tire and 225 mm tire throw away water at the same speed, it means that 225 mm tire will throw away about 10% more water because it is wider. As a result, wider tire will get more resistance from water and starts to hydroplane sooner. Of course, none of the above takes into consideration tread pattern, actual water paths and speeds, etc. Just a general tendency... I hope it makes sense. |
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| Nobody has brought up that with regard to hydroplaning you need to consider the square root of the vector of the hypotenuse of the rotational angle. As the rotational velocity approaches the speed of light, time (and the water that is being shoved aside) move more slowly. So, the faster you go the more likely you are to hydroplane, and cause a tear in the time-space continuum. Once a rip has been made in the time-space continuum, hydroplaning approaches certainty but will never quite attain certainty. Wormholes can also affect hydroplaning and be instrumental in mending the tear in the time-space continuum. ;<). danandkat | |
You forgot to mention that space also start to curve at those rates of speeds and the car can be steered more easily around potholes and steep corners... 
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