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Roadster tends to aquaplaning

Discussion in 'Roadster' started by nikwest, Sep 20, 2011.

  1. nikwest

    nikwest Member

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    I have my roadster now for about 3 months and drove about 7000km. I already had two scary aquaplaning events. I really can't remember that any other car I owned before was so prone to aquaplaning.

    Did you have a similar experience? Are there other tires which might be better than the standard tires coming with the roadster? Or is it due to the weight distribution?
     
  2. AndrewBissell

    AndrewBissell Member

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    Could you give us some details of your incidents?

    Reputedly the Lotus Elise is also prone to aquaplane.
     
  3. AnOutsider

    AnOutsider S532 # XS27

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    Never having driven a roadster in the rain, I wouldn't know, but if I were to guess, I'd say weight could be a part of it. Normally if I feel the car I'm in begin to do it I ease off the gas and let the car settle back down onto itself (with no forward -- or reverse -- momentum to lift it) and I'm fine.
     
  4. Doug_G

    Doug_G Lead Moderator

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    The tires are a big part of this. AD07 aren't particularly great in the rain, A048 are worse.
     
  5. kgb

    kgb Member

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    #5 kgb, Sep 21, 2011
    Last edited: Sep 21, 2011
    Wider tires and insufficiently inflated tires are more prone to hydroplaning. Also, higher speeds are more likely to cause hydroplaning. As a defense, I suggest you use the standard tire inflation pressures instead of the comfort pressures (assuming you are using comfort). Also, the street legal racing tires have fewer tread spaces to channel water away. (a nod to Doug_G's post).

    I've had my car 11 months, and I somehow managed to miss all the hard rains we've had. I've driven on some wet roads, but not through any significant puddles. Because of the "racing" tires that came with the Roadster, I instinctively slowed down a lot the few times I thought I was at risk for hydroplaning. But I can tell you that the traction control helps a lot on ice (and I assume it helps the rear tires when you hydroplane - but it won't help the fronts steer).
     
  6. tennis_trs

    tennis_trs 2010 2.0 Roadster Sport

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    I've had my Roadster for 2 years and driven through a good bit of rain and puddled water with it. I'd say it seems less prone to hydroplaning than the Z4 or Boxster that I had before the Tesla and they weren't bad either (I expect that they were probably a little worse due to wider tires). I've had AD07 tires on my Roadster Sport the whole time. I got the AD07's instead of the A048's because I figured the A048's would be dangerous in the rain and wear much quicker than the AD07's, which wear very quickly.

    In any car, with any tires, it's a good idea to follow kgb's: "I instinctively slowed down a lot the few times I thought I was at risk for hydroplaning."
     
  7. NigelM

    NigelM Recovering Member

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    Same here. I have the factory AD07's and never felt at all uncomfortable...was out in tropical rainstorm just yesterday. Few years back I had a Z3 which was an absolute nightmare in rain and especially on ice.
     
  8. dsm363

    dsm363 Roadster + Sig Model S

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    It's only rained hard once since December where I live in Texas but the AD07s did fine.
     
  9. Lloyd

    Lloyd Active Member

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    There is a formula for calulating the hydroplaning speed in Aviation:

    DYNAMIC HYDROPLANING.
    Dynamic hydroplaning occurs when standing water on a wet runway is not displaced from under the tires fast enough to allow the tire to make pavement contact over its total footprint area. What happens is that the tire rides on a wedge of water under part of the tire surface. And it can be partial or total hydroplaning, meaning the tire is no longer in contact with the runway surface area. It is possible that as the tire breaks contact with the runway that the center of pressure in the tire footprint area could move forward. At this point, total spin-down could occur and the wheel stops rotating, which results in total loss of braking action... not a good thing. The speed at which this happens is called minimum total hydroplaning speed.

    The formula that is used to
    compute hydroplaning speed is: Minimum total hydroplaning
    speed (knots) equals 9 times the square root of tire inflation pressure (psi) or:
    V = 9 ÆP
    For the B-757 main wheels, the speed would be:
    9 Æ144 = 108 knots
     
  10. Doug_G

    Doug_G Lead Moderator

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    For a Roadster's front wheels that would be around 100 kph...
     
  11. zack

    zack Member

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    I felt it once, and immediately got off the freeway. It happened on a very wet entrance ramp as I was giving someone a test ride in the car. Very squirrely, very scary.
     
  12. Dragon

    Dragon Lightning Green Fairytale

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    I'm using Yokohama AD07. I managed to get myself already many times in extremely heavy rain (the kind where you can't see more than 5 meters before you and the water kicked up by the tires will produce 1-2 meter fountains), I never even thought about aquaplaning. The car always seemed fine. Well, maybe because I always instinctively slow down when it rains. If you drive it aggressively you probably will get a problem. And I would never drive in rain with TC off, that would just be stupid.
     
  13. dsm363

    dsm363 Roadster + Sig Model S

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    I agree. It was raining so hard I was only driving 30 mph and could barely see more than a few car lengths ahead of me so I didn't really test out the limits either. Didn't really want to either.
     
  14. Doug_G

    Doug_G Lead Moderator

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    One thing I've noticed is that the steering can be a little squirrely if the front tires are above 30 psi. So that might be a contributing factor.
     
  15. S-2000 Roadster

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    The tire manufacturers would have us believe that their tread pattern is responsible for reducing hydroplaning. But where is the tread pattern factored into those equations above?

    Nik, which tires do you have? Are you driving a Sport?
     
  16. Lloyd

    Lloyd Active Member

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    I'm not sure on this, Aircraft tires are pretty much all the same design with minimal tread pattern. It would be interesting to know how much diffference a tread pattern actually makes. Formula 1 cars will switch to a treaded tire rather than slicks when the conditions become wet.
     
  17. S-2000 Roadster

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    In my experience with several full sets of high performance tires for my Honda CRX Si over the span of two decades, I've certainly noticed significant difference due to tread pattern. Here in Seattle, we get plenty of rain. I quickly became familiar with certain spots on the freeway where water would flow in a sheet across three lanes, and I also became familiar with how my CRX would hydroplane in those areas (which were curves!). Eventually, Yokohama came out with the AVS Intermediate around the time when I became tired of replacing autocross "slicks" (well, minimal tread) and pronounced road noise. The AVS Intermediate tires would plow right through those sheets of water without the slightest hydroplaning. I wasn't the only one who noticed. Yokohama eventually reduced the price of the AVS Intermediate - and their web site gave the reason as the fact that they had already earned back all of the engineering costs of development for these tires. You can imagine that I really welcomed the opportunity to buy a proven high performance tire at a very low cost. Unfortunately, they discontinued them. I assume that they still have advanced tread patterns on certain other tires that remain in their line.

    In any case, the aircraft equation for hydroplaning is interesting. I do maintain consistent tire pressure even when I change to a different tread pattern. Now that I know pressure has an effect, I might try altering it. This assumes I ever have issues with hydroplaning again.

    On my non-Sport Roadster with stock tires, I have never had any hydroplaning in the months that I've driven - and there has been plenty of rain.
     
  18. tennis_trs

    tennis_trs 2010 2.0 Roadster Sport

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    Does your Roadster have just your 7000km, or did you get it used and it have more km on it?
    Are your tires standard base Roadster tires (AD07), standard Sport Roadster tires (AO48), or other? How many km do they have on them?
    Tread depth left is supposed to make a large difference in hydroplaning, so if the wear bars have hit the outside, or worse, then they should hydroplane a lot more than new copies of the same type of tire.
     

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