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Offline diabloinoz

  • 300kph+ club

  • Joined: Nov 2013

  • Drives: Diablo 6.0
  • Location: Sydney
Brenton.

Check out this site ... I have used them for YEARS.

http://www.carbibles.com/tyre_bible_pg4.html

Calculators for original to modified and what the rolling radius (and as such your speedo) difference would be.
Also compare against your original tyre size and can also check different wheel and tyre combos.  Exceedingly useful.

I personally would go with 1 size down for track work, and increase wall size, and thereby reducing the rolling momentum that comes with a larger wheel.  Makes the car more dynamic and controllable in corners.  Think of a large bicycle wheel spinning in the air, now try to turn it ... then do the same with a small bicycle wheel ... much easier and less lag to turn the smaller wheel.

But then it will depend what your suspension setup is as to how much roll vs slide you're trying to invoke before she just lets go altogether.

This is the fun part isn't it ... experimenting and playing to get what works for you.



Offline Ferrari Fissatore

  • Soap Dodger

  • Joined: Jan 2007

  • Drives: its obsession
  • Location: under its skin
How much are a set of 18s in each brand grant?

I know for certainty from experience that kumho and toyo aren't up to the job on big heavy cars like Ferraris, they are not strong enough in the carcass, but for cars under ~1300kg or there abouts they're probably fine.

On a 308, running 16", Dunlop are best, by a fair margin. Both in speed, and more importantly, in utter trustworthiness when loaded heavily.

It's the tyre of choice for majority of tarmac rally people.



Offline Ferrari Fissatore

  • Soap Dodger

  • Joined: Jan 2007

  • Drives: its obsession
  • Location: under its skin
I would also go for the smallest circumference that will work.

It will lower centre of gravity, improve steering response, and reduce overall gearing in every gear, improving acceleration.

Your Speedo won't be accurate though....

The negatives are brakes that work harder (wheel speed is higher), and tyres wear out quicker.



Online Horse

  • Hung like Einstein

  • Joined: Apr 2006

  • Location: Brisbane


On a 308, running 16", Dunlop are best, by a fair margin. Both in speed, and more importantly, in utter trustworthiness when loaded heavily.

It's the tyre of choice for majority of tarmac rally people.

Which Dunlop and which sizes for a 308 - i don't see the correct ones?
Why such a long face?



Offline B2

  • Slowest Ferrari Owner

  • Joined: Apr 2008

  • Location: Melbourne
Which Dunlop and which sizes for a 308 - i don't see the correct ones?

Horse, I ran 205/55 on the front, 225/50 on the rears.  30 psi hot.

Sorry Brenton to hyjack.



Online Horse

  • Hung like Einstein

  • Joined: Apr 2006

  • Location: Brisbane
Horse, I ran 205/55 on the front, 225/50 on the rears.  30 psi hot.

Sorry Brenton to hyjack.

Hi Brett,

They don't list the 225/50's on their website.

Lol at the pressure.

Sorry Brenton to hyjack.
Why such a long face?



Offline Brenton

  • 300kph+ club
  • DJ's like a mad ...........

  • Joined: May 2009

  • Drives: Yes
  • Location: Adelaide
B2 no worries it is atleast on topic more than most threads.

What psi when hot is the good middle ground for the toyo888



Offline 993tits

  • Pepé Le Porsche

  • Joined: Jan 2008

  • Location:
  • Drives:
B2 no worries it is atleast on topic more than most threads.

What psi when hot is the good middle ground for the toyo888

I think you want to target around 32-34psi when working hard.
In my Porsche I would start cold at around 26, put up with the moving around for a couple of laps and then gradually work the pressures out during the day. The pressure change between cooled down and hot will vary during a track day so you might find that the tyre cools, drops only a small amount of pressure and then when you go back out, the pressure increase is quite high again and you have to release some air. You'll get the hang of it. Don't forget to heat cycle new tyres too.
Always Gunna



Offline Brenton

  • 300kph+ club
  • DJ's like a mad ...........

  • Joined: May 2009

  • Drives: Yes
  • Location: Adelaide
Cheers again

I fluked it last Sunday.
Took it down to 27 and then all day it would just go upto and sit at 31 at 45degrees after lap 2 and then stay there.

Didn't touch them again all day




Offline B2

  • Slowest Ferrari Owner

  • Joined: Apr 2008

  • Location: Melbourne
Hi Brett,

They don't list the 225/50's on their website.

Lol at the pressure.

Sorry Brenton to hyjack.
This is what I run Jon.  The 225/50's are listed here.  Not sure why you can't get them in QLD.

http://www.stuckey.com.au/tyres_details.aspx?TyreName=DZ03G

I've run lower than 30 with good results. ;)  1min 56 comes to mind. :D



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