limpetminer
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| posted on 2/5/17 at 09:16 PM |
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Track day tyre pressures
Need some advice regarding tyre pressures on a MK Indy with gsxr 1000 motor, I currently run 16 psi front & 18 psi rear for road use but must
admit it's a bit of a guess. Is this about right or should it be more for a track day?
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jeffw
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| posted on 2/5/17 at 09:22 PM |
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What tyres?
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limpetminer
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| posted on 2/5/17 at 09:25 PM |
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Toyo t1rr 195/50x15
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jeffw
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| posted on 2/5/17 at 09:36 PM |
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Road tyres then. There will be hoards of people who will disagree but....you can't really run road tyres that low as they have softer sidewalls
that motorsport tyres. You should be running something like 22 fr 20 rear on the road. R888R you would get away with 20 fr 18 rear.
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limpetminer
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| posted on 2/5/17 at 09:45 PM |
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What about camber settings front & rear ?
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Angel Acevedo
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| posted on 3/5/17 at 02:32 PM |
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Have you done the Chalk Test for Tire Pressures?
This can provide a baseline pressure.
Then you can adjust a couple of PSI up or down at a time.
HTH.
Beware of what you wish.. for it may come true....
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limpetminer
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| posted on 3/5/17 at 02:41 PM |
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Whats the chalk test?
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SJ
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| posted on 3/5/17 at 02:54 PM |
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With my Yoko A539s I ran them about 14psi all round for track days. That was the best way to warm them up. It didn't seem too low in any way to
me. My Indy has a Zetec as well so will be heavier.
I have R888s now but haven't yet tracked them.
[Edited on 3/5/17 by SJ]
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Angel Acevedo
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| posted on 3/5/17 at 03:05 PM |
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The Chalk Test is as follows.
Find a level test ground, to allow a few revolutions of the wheels in a stright line.
Mark the threads of all tyres with chalk across the thread.
roll the car a few meters, 2 or 3 turns of the wheels.
"read" the chalk "wear" if the chalk wears in the center, there´s too much air pressure, if it wears on the edges, there´s too
little.
Adjust pressure as needed. do it again ´til it wears evenly. front and rear may not need the same pressure as well as side to side, but will provide
starting point.
This test may show that you require camber adjustment.
And last, but not least, on track a pyrometer check will show exactly what you need according to track, speed and driving style.
Beware of what you wish.. for it may come true....
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sam919
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| posted on 3/5/17 at 03:09 PM |
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Set them all to 16psi and do a few sessions, come back and set them when hot to 21psi.
Camber should be done by getting an equal temp over from the inside to outside within 10deg, if too much temp on the inside increase the camber
positively towards 0. Too much temp outside decrease negatively to ward 0.
Too much in the middle over inflated and too much on the outers under inflated.
Typically with track day tyres from Kumho to R888 you should see the left rear getting most heat, then the right, then front left and finally front
right.
I'd set my race caterham RL - 14psi RR 15psi FL 17psi and Fr 18psi it would all equal out around 21psi on a warm day.
My fury with a 919 engine was approx 1 psi different from above - RL - 15 psi RR - 16psi FL - 18psi and FR - 19psi.
Unless really pushing for 15-20 mins anything around 20 psi all round will be fine.
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Nathsx
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| posted on 3/5/17 at 04:26 PM |
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Might help
http://www.locostbuilders.co.uk/forum/52/viewthread.php?tid=157598
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