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Race Starting Cold Tyre Pressures
Home away from home
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One for the race guys here- what sort of cold tyre starting pressures are you using and what sort of temperature climbs are you getting once hot?
Cheers
Dave

Posted on: 2017/11/30 21:17

Edited by B110SSS on 2017/12/1 0:53:32
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Re: Race Starting Cold Tyre Pressures
Home away from home
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There are to many variables in your question to answer
Brand/compound/temp on the day/laps you do
I start with 22psi using Hankňok semi slck

Posted on: 2017/12/1 10:11
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Re: Race Starting Cold Tyre Pressures
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Thanks Greg, realise that it was a fairly open ended question but I'm curious to try and get some ballpark figures from fellow racers.
FYI I tried a Silverstone slick last weekend ( some cheap old stock from Palmside here in Christchurch ) and was advised to start approx 6psi lower than what I normally start which seemed bloody low- given my normal starting pressure was 24 cold. The car did feel ok for 3 laps then started to get somewhat twitchy as the laps wore on.Also the left front was starting to get 'humps' on the outer 20% which is really strange with Ruapuna being bulk left hand turns (underinflation? ). Race 2 went back to 24 psi cold and the car felt way better but unfortunately got less than 2 laps in as it jammed in 3rd coming onto the front straight....
I have my suspicions that these Silverstones are really a 'R' type casing with a slick surface.
They are still ok but probably best for club days.
Cheers
Dave

Posted on: 2017/12/1 19:15
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Re: Race Starting Cold Tyre Pressures
No life (a.k.a. DattoMaster)
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Dave,

On the Hoosier Street TD bias ply tires I start between 20-22 cold. I'm looking for 24 hot. Some specs I found recommended 18 cold (car is 759 Kilos + me 62-63 823kilos). I found that to be a little low and went back up.

On the tranny did the synchro collar over travel? That's what happened with mine.

Posted on: 2017/12/2 22:13
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Re: Race Starting Cold Tyre Pressures
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Hi Tom,
Still waiting for my mechanic to get back from Australia. I've whipped the box out and dropped it off at his workshop so hope to have an answer later this week.
Cheers
Dave

Posted on: 2017/12/3 3:29
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Re: Race Starting Cold Tyre Pressures
No life (a.k.a. DattoMaster)
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I saw pictures of a 73-series box where the cut grooves in the shift rail to prevent the box from over traveling.

When my 56 series U/C box stuck in third it felt exactly as it always does except it would pull back to 4th. The synchro, while worn, was still within tolerance so the mod to the shift rail seems like a good idea.

Back to the tires; mine felt almost identical at the lower pressures the only difference was the slower lap times, which initially had me scratching my head but as with all things race car you just have to ask yourself what did you changed. As so as I went back to the original pressures the lap times returned.

Posted on: 2017/12/3 18:42
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