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Old 10th October 2013, 11:39   #1
MuZiZZle
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Default Tyre Pressures

What would you guys suggest front and rear for my VTS on 888s this Sunday?

Mid 20's?

I've never really played about with them too much
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Old 10th October 2013, 12:20   #2
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I'd probably start at that, with a little higher at the rear. Really you need to have a tyre temperature sensor and then test the car after a few laps to work out the track running temperatures.
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Old 10th October 2013, 12:37   #3
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If your going as far as tyre temp gauge ,then first thing you should do is use nitrogen and not compressed air
pressures will not alter anything like as much ,maybe 50% less pressure change than air.
which is why real race tams use it and why aircraft tyres use it
can you imagine 747 tyre pressure sat on dubai at +50c --then climb to 37000feetair temp -57c
then decend to heathrow --tyres would flat if they used compressed air and there could be a lump of ice in the tyre
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Old 10th October 2013, 12:37   #4
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I'd probably start at that, with a little higher at the rear. Really you need to have a tyre temperature sensor and then test the car after a few laps to work out the track running temperatures.
it's Scotland, in October! -16?

How much more in the fronts than the rears?
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Old 10th October 2013, 14:25   #5
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I can't comment on R888s, but this seems to works for me with 595 RS-Rs: Set to 2 bar from cold and check pressures after first stint on track. Fronts are usually around 2.3 bar at this point, so check and reduce all tyres to 2 bar.

I could be wrong, but if 888s/ A048s require lower pressures, try the above but use 25 psi? I've got a funky little pressure gauge if you need a borrow.
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Old 10th October 2013, 15:37   #6
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Would it get between my spokes?

fnar
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Old 10th October 2013, 16:02   #7
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Quote:
Originally Posted by axsaxoman View Post
If your going as far as tyre temp gauge ,then first thing you should do is use nitrogen and not compressed air
pressures will not alter anything like as much ,maybe 50% less pressure change than air.
which is why real race tams use it and why aircraft tyres use it
can you imagine 747 tyre pressure sat on dubai at +50c --then climb to 37000feetair temp -57c
then decend to heathrow --tyres would flat if they used compressed air and there could be a lump of ice in the tyre
if your going to run nitrogen it kind of defeats the object if your not going to replace with nitrogen once your at the track if your changing around tyre pressures

for a full blown race car yes, for a one hit wonder i dont see the benefit (compressed air is 80% nitrogen anyway)
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Old 10th October 2013, 16:11   #8
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Would it get between my spokes?

fnar
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Old 10th October 2013, 17:50   #9
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I always run 26 front, 24 rear COLD.

After you come off, they should be around 30-32 hot front, and 28-30 hot rear.

After this, drop them when they are hot by the amount they increased from cold, that way if you keep doing this they will start to be in the ball park.

On Z209s i like 26 front 24 rear HOT. The rear needs to be able to move around to generate heat (obviously cause the car is FWD)
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Old 10th October 2013, 17:58   #10
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I used 28 on front and 26 -27 at the rear ,
the air we breathe is already 81-82 % nitrogen , so not really worth it if you are going to be checking tyre pressures adding- taking out air , unless there is a nitrogen pump on site!
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Old 10th October 2013, 18:23   #11
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I wouldn't bother with nitrogen.

You might find this helpful:
http://www.106maxi.co.uk/mediapool/7...T_UP_R888.docx
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Old 11th October 2013, 07:19   #12
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^ just a quick question , what would be the temperature for a cold pressure??? 18-21*C ??
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Old 11th October 2013, 09:24   #13
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It doesn't matter, always set your pressures when hot.
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Old 11th October 2013, 14:05   #14
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i tend to start out mid 20s

at the ring in august i ended up going down to COLD pressures being 21 front 19 rear on r888s

was nice and warm then so as soon as you got on track you could feel in a few corners the pressures come up
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Old 11th October 2013, 18:29   #15
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Has anyone used or seen this? http://www.demon-tweeks.co.uk/perfor...ng-system-tpms

Seems reasonably priced compared to others but dont actually know what its like. Personally think it could be very useful as i have a passenger so they can keep an eye on the temps and pressure and tell me what is happening
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Old 11th October 2013, 20:00   #16
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When you get your pressures set right, they are set right.
I've done 20 min races and 40 min races and the pressures don't keep rising.
Get an infra-red temp gauge and use that to make sure your geo is right, and also get a decent pressure gauge.
Spend your time at the track recording track temp, tyre temp, and pressures.
Set them hot, and you are pretty much sorted.
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