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Old 07-16-2008, 08:31 PM   #1 (permalink)
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Short tire pressure story

On the way home tonight in the Paseo I hit a torrential downpour. Everyone on the highway slowed down to around 40-50 mph. I could only see about 100 feet and I saw lights about 150 feet. So, it was pretty bad. Think I had any problems at all with my tires at 60 psi? Not at all. It rode through the rain like a champ. Thats my short story for what its worth.

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Old 07-16-2008, 08:43 PM   #2 (permalink)
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Thanks for reminding me I need to air mine up before the 1000 miles of highway I'm doing tomorrow,
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Old 07-16-2008, 08:54 PM   #3 (permalink)
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One theory I read during the last round of tire speculation was that with less pressure in the tire there is more tire in contact with the ground, and thus the tire is more like a waterski. <shrug>
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Old 07-16-2008, 08:56 PM   #4 (permalink)
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was this an "emergency stop"?

My qualms with safety things like tire over-inflation is this: if you and I hit the brakes at the same time, you on your overinflated LRR tires and me on my UHP summer tires with rain tread at proper psi, I'm simply going to stop first. I just don't like the idea of anything other than being able to stop first.

However, my kudos to you in being a good driver looking ahead and driving within the limits of your vehicle. Many well-equipped people can't receive the same kudos.
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Old 07-16-2008, 08:57 PM   #5 (permalink)
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Running 50psi I've never had any trouble with water...my mom's car at 32psi hydroplanes like there's no tomorrow, though...

Of course this is all hearsay until one of use gets out and does some serious testing,
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Old 07-16-2008, 08:58 PM   #6 (permalink)
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Doax , I will have to agree with you, for you guys summer gives you some of your best mileage, for me it means 3-4 days a week of rain if not everyday. With that said, riding @ 50psi I have noticed no hydroplaning and in some circumstances better corner handling with the wet weather. Mind you I am not going out of my way to test wet weather traction, but the car does feel less sloppy than what memory serves.
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Old 07-16-2008, 08:59 PM   #7 (permalink)
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BTW Doax ... what is max sidewall for your tires? And do you run 60 in all?

I was thinking of bumping the fronts up to 55 and leaving the rears @ 50 since I have so little weight back there now ...
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Old 07-16-2008, 09:02 PM   #8 (permalink)
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Well, I kind of avoid that to some degree. When 'driving without brakes' you really increase the space cushion and don't follow as closely. However, on this trip I did have to make one pretty quick slow down (I couldn't see very far after all) and had no problems at all. I honestly can't even remember the last time I had to put on my brakes that hard...

Your concern is valid though MazdaMatt. I had planned on doing some brake testing at various psi with my gtech when I had the chance. Its still not done unfortunately. When I get the chance the forum will see the results.

Max sidewall on these tires is 44 psi. I run 60 psi in all four.
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Old 07-16-2008, 09:08 PM   #9 (permalink)
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My first racing school it rained and i was in my DD on my street tires. They were brand new with a mean rain tread and I had excellent grip. I tuned in my tire pressure to the best grip. The next day it was sunny and I was able to bump up about 5psi in each tire before acheiving maximum grip.

Everything in life is an optimazation problem. I don't drive a minivan because I don't need 7 seats. I can't go telling a family of 7 to go buy an econobox. if you air up your tires for psi, you have to drive more carefully, if you do so, you have no loss. You optimize your mileage and lose out on some other aspects. no biggie as long as you know your car's limits.
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Old 07-16-2008, 09:21 PM   #10 (permalink)
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I'd argue still that when you have a smaller contact patch, you drive water out from under your wheel faster due to increased pressure on the water. When I switched from 245/45/17 to 315/35/17 tires in my mustang (got bigger wheels for looks and altering the car's stance only - I've never believed in contact patch - friction relationships) I lost rain performance. I can hydroplane all the time now in that car.

I'm sure there is a speed at which the greater pressure just won't matter due to the water's viscosity, but I haven't ever experienced it.

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