Rex,
I may be a little slow on the uptake but.....what is the value of an
"unloaded" spin test? We don't run cars "unloaded" do we? .....I keep
thinking about the shape of a dragster tire at 300+ and the distortion
caused by power application and weight.....
So what happens to your tire at 300 with 1000 lbs on it and a traction
coefficient of .6 applying 600 HP to a flat surface? Is there a factor that
can be applied?
Skip
At 11:21 AM 7/2/03 -0600, you wrote:
>List:
> Here are spin test results on the tire I use on my car. The test
>was done to gather safety information not otherwise available on this
>tire. These results are for information and entertainment only, etc.
>Many thanks to Gene and Betty Burkland (and Betty's brothers) for taking
>the time and effort to do the test.
>
>
>Tire: New, off the shelf, Michelin Pilot Sport 275/40 ZR 17
>unshaved.
>tire air pressure- 50 psi
>mounted tire out of round- .006"
>start circumference- 80.6875"
>air temp. 70' F
>
>test- tire held at noted RPM's for 20 seconds, then stopped and
>measured. free (unloaded) spin
>
>Spin # 1: 2,000 tire rpm radius growth 1/8" 155
>mph
> 2,500 tire rpm radius growth
>1/4" 196 mph
> 3,500 tire rpm radius growth
>5/16" 275 mph
> circumference at rest- 81"
> tire psi after run- 50 psi
>
>Spin # 2: 4,000 tire rpm radius growth 1/2" 319 mph
>
> 4,500 tire rpm radius growth 1/2" + 359
>mph
> circumference at rest- 81.250
> tire psi after run- 50 psi
>
>Spin # 3: 5,000 tire rpm radius growth 5/8" 403
>mph (spinner operators were backing up at this point)
> 5,172 tire rpm tire
>failure 417 mph
>
>Notes: no shake or vibration during the test. The bead was stable on
>the wheel until 200 rpm prior to failure.
> parts of the tire flew 500' from the spinner which was
>pretty cool to watch & we were hunting tire pieces for 30
> minutes in the wheat field.
> Using a 68% safety factor there is still a large margin
>when running the car at 200 mph.
>
>Rex Svoboda
>631 G/MS
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