Quick advice - track day tire pressures

Discussion in 'General VFR Discussions' started by Rustysalami, Jun 10, 2016.

  1. Rustysalami

    Rustysalami New Member

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    Howdy all. Last minute decision to do a track day tomorrow. I understand to let the tyres down a bit from my previous bike and track day, but this is my first time on the viffer.

    Any advice appreciated. Temperature should be around 25 Celsius. I'm using Michelin PR4 tyres. I'm only 74kg.

    I'm thinking 30psi front and 36 rear?? I don't want to be wasting time dialing it in over a few sessions.

    Cheers

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  2. Marrib

    Marrib Insider

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    When it was 80 here, the tech guys told me to put my BT016's at 30/32. Hopefully that will give you a ball park figure for your PR4's.
     
  3. James Bond

    James Bond Member

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    I'm just going to go ahead and tell you the truth in answer to your question. Lower the pressure on both tires, ride the bike, remember how it felt, adjust the pressure again, ride the bike and continue carefully doing this thru trial and error. There IS NO MAGIC formula. It depends on the tire, your suspension, the ambient temperature, the track temperature, your riding style, your riding skill, the riding surface, and things I don't think anyone even understands. The best advice you can get, me thinks, is to do your adjustments very carefully and ramp up your speed very conservatively until you hit those "aha tire pressures for the particular tire you're using at the time". This method is how I learned to ride in all conditions and even different geographic places in the country require different riding parameters. Long vague answer to a direct question but don't go out thinking there is a silver bullet answer to your question. Let us know what works for you. ; )
     
  4. Rustysalami

    Rustysalami New Member

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    Thanks. I'll stick with the 30/36 for starters. See how I go ;)
     
  5. baz263

    baz263 New Member

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    It's hot tyre pressures you should be looking at. If you can take a reading as soon as you finish the session it will help. That way you can see if you get an increase in pressure during the session. 30/36 is a good starting point but it may be too high. If you get back in and they are back to 36/40 or so you can adjust accordingly. If you had warmers you would take the pressures hot. Have fun.

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  6. Rustysalami

    Rustysalami New Member

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    [​IMG]

    Had a ball. Photo of rear tyres that got a descent workout. Only a little chicken strip left. Used 30 front 34 rear.


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  7. Glenngt750

    Glenngt750 New Member

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    You are wanting a 10%-15% rise in pressure from cold to hot. Your tire choice is more road oriented, but if they worked for you, great. 20 years ago those "sport-touring" tires would've been really aggressive super sport tires.
     
  8. Rustysalami

    Rustysalami New Member

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    They were squirming around a bit on the corners, but hey they aren't sport tyres


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  9. K5Dave

    K5Dave New Member

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    30front 28rear
     
  10. Mohawk

    Mohawk New Member

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    Whatever you do, remmeber double & halve to dial in quickly. So if you think 4psi reduction is right then double it to 8psi. Test if bad you KNOW which way = get better, so halve the difference, to 6psi, try again. Remember when cold the front will feel flat, the rear doesn't really care until you get below 25psi.

    Tyre pressure increase roughly as follows;- ".16 psi per Celsius degree"

    So if filled at the nominal cold temp of 20c to 30psi, then at a 30c tyre temp the pressure will rise 1.6psi, at 40c it would be +3.2psi etc. 25c ambient will easily create 35-40c track temperature & 40-50c tyre temps. So a 50c tyre would be 4.8psi higher or 34.8psi.

    YMMV
     
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