# Street tire static and kinetic friction coefficients?

#### ektrules

Anybody know where I can find data on normal street-tire friction coefficients on dry asphalt? I'd like both the static, and the kinetic coefficients. If not, can somebody give me a range of reasonable values?

While I'm at it... What about racing slicks on asphalt?

I found one source that said the static friction coefficient of a tire on concrete is about 1. But, it didn't say what kind of tire, didn't give me the kinetic coefficient, it's on concrete, and it seems too high.

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#### xts

You may calculate static coeff from breaking distance of cars using ABS. For most family cars breaking distance on dry asphalt from 100 km/h is 45-50 meters, thus (static) friction coefficient is 0.8-0.9.
Porsche 911 Carrera Turbo on rally tyres on standard German asfalt pavement claims breaking distance of 34.5m => f.coeff=1.1

Regarding kinetic coeff: police forensics use coeff=0.7 for dry and 0.55 for wet asphalt to compute speed from skid marks during collision investigation.

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#### jack action

Gold Member
http://hpwizard.com/tire-friction-coefficient.html" [Broken]

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#### ektrules

Oh, cool. Before I started this thread, I got search results from that site, but the site was down at the time. I didn't know what was on that site. Thanks.

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