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I've googled all over the internet and believe it or not I can't find any answers to this question...

Why does my car lose traction for a second when I drive over painted road lines?

Here's a perfect picture...

enter image description here

When I drive over hose solid white lines (yes I understand you're not supposed to switch lanes when the line is solid) while driving around 40-50 MPH, my car wants to do that "scooby-doo" move like it's going to fall over.

Why, though? It happens ON DRY ROADS. I can understand if it was wet, but when everything is completely dry, I don't think painted road lines should be a hazard. :(

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    can you take close-up pictures of your tire treads and add them to your post ? that would be a lot more helpful than the intersection that you have right now, which we all know what it looks like ...
    – amphibient
    Jul 7 '15 at 15:37
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There is a very simple answer.

The friction co-efficient on the paint lines is lower than the pavement. It's pretty common on almost any paint line in any state within the Union.

That being said, some road racing governing bodies like the FIM and FIA force circuits to use a particular type of paint with grit in it that has a higher friction co-efficient than pavement for reasons of safety of the drivers.

There is a state, do not recall, that has a similar requirement that there DOT has instituted for state highways.

If I can find it, I will edit this and post.

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    While that is true it is insufficient to explain the "scooby-doo" loss of traction at what the OP is describing at normal driving conditions and speeds.
    – elmerfud
    Jul 7 '15 at 23:22
  • It absolutely is. The friction co-efficient of paint is lower than pavement, hence the scooby doo effect of lower traction on braking or acceleration on a paint line. Jul 8 '15 at 0:56
  • Wrong, for normal driving crossing painted lines is not a safety hazard. The OP said nothing of heavy acceleration or braking only driving at a moderate speed (40-50). I think you're confusing track driving and normal road driving, also possibly the stability of 2 wheeled vehciles vs 4 wheeled. Properly running street cars do not behaive this way while crossing painted lines unless the car has been modified, is exceeded the posted limits, or is broken.
    – elmerfud
    Jul 8 '15 at 3:04
  • I'm gonna go ahead and agree with elmerfud here. While I can imagine that the painted lines would have some effect on my tires... I shouldn't be damn near smashing in to nearby cars just by going over one. Jul 10 '15 at 18:51
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There are a number of factors that could contribute to this happening.

  • Improperly inflated tires If your tires aren't inflated correctly for their size and the weight of your vehicle they may not have a proper contact patch with the road.
  • Very Soft (sport) tires Very soft tires are great for gripping a rough surface like concrete or asphalt. They kind of mash in to all that roughness gaining extra contact area. Paint tends to fill in that roughness and produce a nice smooth surface. Those soft tires have nothing to mash with so all that softness makes them slightly "greasy" when on something smooth.
  • Old Tires Tires that are old you should see visible cracking around the rim, and deep cracks between the tread. The rubber is worn out and as it's transitioning over the varying surface the different tread blocks are moving differently.
  • Suspension/Bushings The scoobydoo feeling may be bad suspension magnifying otherwise normal tires transition over varying mediums.
  • Wheel Alignment Improper alignment of the wheels may be a major contributor as well. If the toe setting is wrong off it's possible that as a wheel moves over the line it wants to "dart" slightly. Improper camber may also be preventing the correct sized contact patch with the road.

If your vehicle is not stock, bigger tires or rims, raised or lowered, then I would tend to lean toward alignment and suspension issues. As altering those parts will change the alignment and the stock alignment numbers aren't always going to be correct to make your car drive correctly.

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Your tyres are probably way too hard. Either because their "energy savers" or because they're very old and are starting to perish (your first clue is tiny cracks in the side wall and/or little shiny spots).

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