Geekery: AWD vs FWD wet weather 0-60 times?

Discussion in 'General' started by MPGee, Jan 14, 2019.

  1. MPGee

    MPGee Active Member

    Hi all,

    (Not sure where this thread should go in the forums.. Mods feel free to move...)

    Anyone know of any #s on the zero to sixty performance times of vehicles in wet weather? Namely, how big a difference there is between the 0-60 times of the AWD vs FWD versions of vehicles?

    I ask, because I feel a little sad whenever I hear wheel-spin in my FWD '07 Toyota Matrix when starting from a stop, and this occurred again last night in the rain. :( (Also, as a hypermiler, I'm not even pushing it hard!).

    There's plenty of #s for dry pavement, which show that the difference is negligible (with the advantage going either way). I know AWD will trounce FWD when the pavement is wet... I'm curious by how much, though.

    I searched the Internet, and could not come up w/ anything on this. (PS. Exciting that Toyota is coming out w/ a Prius with an electric "AWD" which addresses this exact issue, kicking in an electronic motor on the rear axle when starting from a stop).

    Thanks,

    MPGee
     
  2. Carcus

    Carcus Well-Known Member

    I doubt that you'll find any hard data. There's all types of surfaces out there, put water on them (differing amounts of water) and you have all types of stopping ability. Think "all roads aren't created equal" and "all wet roads aren't created equal x 2".

    If you're concerned about traction on wet pavement the first thing I would suggest is running tires of good quality/condition at the vehicle manufacturer's recommended (door post) tire pressure.
     
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  3. RedylC94

    RedylC94 Well-Known Member

    That's pretty much a non-issue on pavement with any of the three FWD cars I've had. A (hypothetical) 4WD version of any of them would've inevitably been slower, because of the added mass and drag.
     
  4. Jay

    Jay Well-Known Member

    ^this. The OEM tires on my FWD Acura RSX were so crappy I could get them to squeal on dry pavement. The answer isn't 4wd, it's decent tires. Even on snow, great snow tires and FWD out accelerates and out stops 4WD and mediocre tires.
     
  5. MPGee

    MPGee Active Member

    Thanks all for your input.

    So, in light of what you guys said, I figured I'd try an experiment... I lowered my tire pressure to mfg spec (32 psi), and holy crap. No wheelspin. I was doing aggressive starts in the rain, and no slippage! I didn't think that running "just" +5 PSI would make a difference.

    I forget what brand my OEM tires were, but I don't recall having these kinds of traction problems. Then I wanted to do a -1 sizing for better ride, lower wheel & tire weight (and in theory, better fuel economy). The 15" wheels came with a set of a 60 series tires in good shape instead of 65 that would have been the right height. I ran on the 60 series until I wore them out, and had significant wheelspin when it was wet...

    OEM wheel/tire size:
    205/55R16, 16x6.5" steel wheel
    Michelin HydroEdge replacement tires
    No wheelspin (as best as I can remember)

    Interim wheel/tire:
    195/60R15, 15x6" steel wheel
    Falkien ZX612
    Significant wheelspin
    (Tire shorter than OEM equiv)

    Current wheel/tire:
    195/65R15, 15x6" steel wheel
    Goodyear Assurance FuelMax
    Some wheelspin at 37PSI, virtually none at 32PSI.
    (Equivalent height to OEM)

    I think I'm a convert.. No more of this running tires inflated higher than spec.. I've run a +5 PSI for years now. It never caused abnormal wear, as best as I can tell, but having good traction is kinda a big thing, IMO... Despite what some people on the forums claim about it being perfectly fine, I think this shows that there is a material difference..
     
  6. RedylC94

    RedylC94 Well-Known Member

    I think there might be a few uncontrolled variables.
     
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  7. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    I'm pretty aware of this. I have been running my new Hankook all-seasons at 40 psi. They seem to
    stick well so far. Wheelspin from acceleration has never been a problem with this car , he says with a straight face.
    If I sense that braking traction is marginal , I will let some air out. In spring time , I will go up to 51 psi. I had good luck
    with my OEM tires at 45 psi ( 44 sidewall).
     
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  8. MPGee

    MPGee Active Member

    That's a nice, polite way of saying, "Uhm... I don't think you see what's going on here.."
    :D

    That's a good point.. Yes, RedylC94. Over the history of my vehicle (other than OEM), I have had a # of factors working against good traction.

    If I'm pondering this correctly, here they are.

    Factors in my vehicle's history that worked against good traction:
    1. High-treadwear rated tires - Harder materials, less grippy
    2. Shorter than OEM overall wheel+tire diameter - Increases the amount of "torque" that the car applies at meeting point of rubber to asphalt. (Sorry, can't explain the sciencey part I think this is. I think https://www.carthrottle.com/post/how-does-wheel-size-affect-performance/ sheds some light on this.)
    3. Smaller wheel size reducing rotating mass - Increases "torque" applied from rubber to asphalt (apologies for my bad sciencey skills).
    4. Narrower tire - Reduces contact patch size
    5. Higher inflation levels - Reduces contact patch size
    The more factors I had at a time, the worse my traction... In other words, my vehicle was designed (aka, geared) for a given setup. I've messed with them, and as a result, my traction may vary...

    With my current setup, I was running with 1, 3, 4, and 5. I think all four of those factors were too much. Now I'm just running with 1, 3, and 4 (aka, I went back to standard tire pressure). #5 was the straw that broke the traction's back.

    Does that sound like a more reasonable analysis?
     
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