F138 Guidelines

1.1 Tyres

1.1.1 Ideal “running” pressures: 28 psi, all tyres/compounds.

1.1.2 Ideal running temperatures – within 10 degrees of :-

  • 100 – Supersofts
  • 105 – Softs
  • 110 – Mediums
  • 115 – Hards

2. DRS

Will be allowed, the ACRL DRS app will be used to catch anyone who uses it when over a second behind the guy in front. The best way to use this app is simply to always wait for the BEEP & react quickly to the “angry” BEEPs you get when using DRS illegally. ACRL DRS App (3301 downloads)

3. Changelog (from original):-

  1. More compliant ride, the original is like a brick on wheels.
  2. Faster turn-in, especially low-speed.
  3. Tyre temperatures/performance/blistering/graining completely remodelled. Not as bad as real-life, but you do have to get the tyres in range now (see above). Balanced wear front-rear.
  4. Remodelled rear slip coefficients to make tank-slappers both more violent and yet more catchable at the same time. Has improved FFB a lot, but also made throttle control more delicate – you have to show this car some respect!
  5. Aero/drag completely revamped, there’s now a big trade off between “more wing-more drag” and “less wing-less drag”.
  6. Higher top speed, not so “asthmatic”.
  7. Slip angles reduced.
  8. Stability over kerbs improved.
  9. Pit times all reduced.
  10. Aligned all the suspension & aero scales with one-another.
  11. Changed default setup so it feels good without any adjustment.
  12. Raised underside collider so that it’s easier to steer on grass and get out of gravel.
  13. Modernised braking behaviour.

4. TyresFX Compounds

5. Tyre Management/Strategy

A bit more about the tyres as they need to be understood to get the most out of them.

  • Blistering & graining – these tyres are particularly sensitive to both. In simple terms, if you get them too hot they will blister and if you can’t get them up to temperature they will slide and grain, but If you keep the temperatures in range (see 1.1.2 above) the wear is actually pretty good – Supersofts can see you over half of race distance. However, keeping them in range over a full race is impossible on tracks like Barcelona or Mugello where the front left takes a hammering, but then it’s even more crucial that you find the best compound/pressure compromise to keep them close to their optimal working range. You tend to get understeer with front overheating, oversteer with rear overheating and a general lack of grip with graining.  In all cases of excessive graining or blistering it will mean an early trip to the pit lane.
  • High fuel versus low fuel – due to the high levels of fuel required at the start of a race (200+ litres), the pressure on blistering will be greatest on the first stint. Equally, to get the car to come alive towards the end of the race you will need to make sure the tyres remain hot enough when the tank empties. A simple rule of thumb is that higher pressures will work better at the start of the race and lower pressures will work better at the end (1 or 2 psi less). On high friction tracks, the 1st stint is always the killer stint, you are literally just seeing off the fuel sometimes.
  • Air/track temperatures – to stop people boring themselves to death practising-practising and more practising in perfect conditions for hour-upon-hour in-between races until they get their strategy perfect for the weekend, I’ve added a realistic temperature variation into the equation. All temperatures are plus or minus 4 degrees (air & surface). At Silverstone, for example, the air temperature is set to 20 degrees, which means it could be anywhere between 16 and 24. The perfect strategy at 16 degrees will not work well at 24, so be prepared to have a different strategy depending on the conditions (perhaps a 1-stop on a colder day, 2-stop on a warmer day – softer compounds in the cold, harder in the warm) and even be prepared to simply react to the tyres on the day. If you’ve practised hour-upon-hour and perfected a change on lap 15 and then in the race you get to lap 8 and feel the tyres are done, don’t kid yourself they will come good again unless you’ve factored it in. Make sure you check the temperatures on the day for both the sprint and the full race.
  • Why I have limited the pressure range from 14 to 18 psi – this is a weakness in AC’s tyre modelling. Basically, the loss of grip due to tyre pressures getting too high or too low is programmed in a linear fashion. There is no fall-off in other words, so the more you increase pressures, the worse the grip will get but only in a linear manner. Therefore I have simply created an artificial drop-off point by limiting the range as I feel it’s more realistic than allowing someone to have 3 tyres at say 16 degrees and the front left at 25 degrees to keep it cool, which would be disastrous in real life but not that bad at all in AC. The solution isn’t perfect.