Assetto Corsa Tyre Types

http://www.assettocorsa.net/forum/index.php?faq/what-are-the-differences-between-tyres-compounds.15/

Road Legal Tyres

Street and semi slicks are road legal compounds, used on the road. They wear out slightly. Their main problem is overheating, but after you have overheat them you can wait and start again, they can give similar grip even after lots of km’s. In the end they will wear and lose grip totally.

Street Tyres

Optimum temp: 75°C – 85°C but “easy” under and over those temps. Very easy to overheat after some laps on a circuit, especially on fast corners.

Semi Slicks

75°C – 100°C but a bit less grip under that and overheat quite faster over that. They have more grip of course and can resist more fast laps, but do not like much abuse and drifting. They wear gradually and lose grip km after km.

GT2 Slicks

The main difference of the GT2 cars is that manufacturers are actively developing tyres during the season and bring different compounds on the various tracks. We cannot of course simulate specific compounds for specific tracks, but we offer 5 different compounds:

• SuperSoft: 90-105°C Don’t like to be driven under or over that range. They wear out very fast

• Soft: 90-105°C as supersofts. they wear out fast

• Medium: 85°C-105°C as supersofts over their range. They wear out in a linear gradual way

• Hard: 80-100°C a tiny bit easier than supersoft outside their range but nothing too radical. They wear just a tiny bit after the initial laps and then stay quite stable for a long time until they start to lose lot’s of grip

• SuperHard: 80-100°C as hards. They wear a tiny bit and stay stable for lot’s of laps until they let go.

GT3 Slicks

The biggest difference between GT2 and GT3 cars are their tyres. GT3 tyres are fixed for the whole season and the organization decides what tyres the car have to use. We provide 3 compounds that are not equivalent to their GT2 counterparts (worse):

• Softs: 80-110°C . Wear VERY fast. We’ve been told that they were actually used only for a couple of times in qualifying.

• Mediums: 75-105°C Wear linearly and predictably. all around tyre

• Hard: 70-100°C Wear a tiny bit after a couple of laps and stay stable for a long sting. Not great grip but they are predictable and can be used in a wide variety of tracks and temperatures. Often “forced” by regulations on cars.

Hypercars Slicks

(Zonda R and 599XX) are a bit worse parents of the GT3 tires. Let’s say a generation behind. Rest of their characteristics is very similar to the GT3 tires.

Vintage F1 67 Tyres

We provide just one compound for such tyres, although we learned there were actually different compounds. As a matter of fact, there is documentation reporting that Jim Clark choose the tyre that permit him to slide more for the race at Monza. Unfortunately there is not enough documentation for the compounds so for now we stick with just one compound. If anybody has more info regarding the matter, I’d be happy to discuss with it. Optimum range 50-90°C. The tyres are good at low temps, and can withstand overheating pretty well. The tyre wear is gradual, you can expect to do a full race without problems, except if you overdrive and overheat them too much.

The tire ranges are not perfect ranges but a min max range that you might not be able to understand a difference in tire grip. Temperatures are also vary quite widely from straight to inside a turn, so optimally you need a tire that stays at the lower end of the optimum temperature just before the braking zone and at the higher end of the optimum temperature at the exit of the turn. Not so easy to obtain.

In AC going outside the optimum range, doesn’t mean the car will become undriveable. This characteristic is a double sword. You might think the car is good, but you’re not driving on the optimum grip, so you’ll lose time without understanding it. There’s depth to be found and explored within the AC tire model.

Another hint for tyre temperatures, as in real life, use more camber to heat faster a part of the tyre tread and then this dissipate to the rest of the tyre. More camber, more heat, less camber, less heat.

Slicks

High surface temp + low carcass temp = graining
Low surface temp + high carcass temp = blistering

You want both the carcass and tread to be equally up to temperature.

Tire temps rise up rapidly as you impose a slip angle, and fall down even more rapidly as soon as you remove the slip angle.

In general, the more heat cycles you put the tire through, the more you "cure" the compound (making it harder), which decreases grip and is what's commonly called "degradation". The intensity of heat cycles is also a considerable variable here. For example, pumping 40kJ of heat into your tires over a single lap will result in more degradation compared to 10kJ over 4 laps.

In F1 you use the brakes to pump heat directly into the tire carcass. Go to a track with small brake ducts and improper suspension setup, you'll see blisters in just a couple of laps.

Reason being, as you enter the braking zone, the brakes begin heating the carcass, but until you steer you don't develop a slip angle which means you don't develop tread temperature. This time delay between you steeping on the brakes and steering the wheels is most of the times enough to end up blistering an improperly set up car.

Even though the tire does lose mass as it's run through a stint (mechanical wear), mathematically this fraction isn't significant. Often it's hardly a few percentage points of the tire's total thermal mass. If anything, the change in rolling radius would theoretically be a stronger influence, but really I'm yet to see a tire where mechanical wear was a significant factor in thermal behavior.

Almost every time it's just the alteration in the tire's chemical composition as it undergoes heat cycling that dominates tire performance.

Underlying cause of blistering is too much shear load on the tread (which generates the temperature in the first place).

This may either be caused due to an increase in lateral slip, arising due to:

• Improper toe/Ackermann setup
• Lack of downforce (dirty air/damage) causing the car to require higher slip angles for the same lateral accelerations.
• Improper weight distribution leading to high chassis sideslip angles.

... or this may be caused due to sub optimal control of wheel loads arising due to:

• Overly stiffly sprung suspension for aerodynamic reasons

Changing any of these will influence the tires' graining tendencies.

https://www.reddit.com/r/F1Technical/comments/ozwi56/effects_of_tire_surface_vs_carcass_temp/