Tyre wear in ACC is real, but it is slower than most people think. If your car falls apart 12 minutes into a 20 minute race, the tyres are not worn out. They are too hot.
So this page does two jobs. It shows you how wear works and how to measure it, and it helps you tell wear from overheating. The fix is different for each.
It sits under the ACC setup guide, which covers the rest of the setup screen.
How tyre wear works in ACC
ACC does not give you a percentage. It gives you tread depth in millimetres, for the inside, middle and outside of each tyre. You find it on the tyre page of the setup screen after you come back to the pits.
A new slick has 3 mm of tread. Here is what happens from there:
- Laps 1 and 2: a new tyre is not at its best yet. It needs a lap or two to scrub in and reach full grip.
- The first laps after that: peak grip. This is your qualifying tyre.
- The rest of the stint: grip falls slowly and steadily as the tread goes down.
- Low tread: once you are well under 2 mm, the car slides more, which wears the tyre faster. It feeds itself.
There is no magic lap where the tyre dies. It is a slope. How steep depends on the car, the track and mostly on you.
How to measure your own tyre wear
You do not need to drive a full stint to know how the tyres will finish it.
- Load race fuel and set the track and air temperature you expect in the race.
- Drive 4 or 5 clean laps at race pace. Not qualifying pace.
- Come into the pits and open the tyre page in the setup screen.
- Write down the tread for each tyre. Subtract it from 3 mm.
- Multiply by the number of laps in your stint, divided by the laps you just did.
A worked example. After 4 laps your rear tyres are at 2.83 mm. That is 0.17 mm gone. Over a 40 lap stint that is ten times as much: 1.7 mm of wear, so you finish at about 1.3 mm. That is a tyre close to its limit. If the fronts lost only 0.13 mm in the same run, they finish at 1.7 mm, and you know the rear axle is your problem.
Real wear is not perfectly linear, because a sliding tyre wears faster. Treat the number as the best case.
Wear or overheating?
They feel the same: the car slides and the lap times drop. But they are not the same.
- Overheating comes on in a few laps and goes away again if you back off for a lap. The tyre widget shows temperatures over about 90°C and pressures above 27 psi.
- Wear comes on slowly over many laps and never comes back.
If the car goes off in the first 10 or 15 minutes, look at pressures and temperatures first. The target is 26.0 to 27.0 psi hot and 80 to 90°C. The ACC tyre pressure guide shows how to get there, and track temperature moves all of it.
Reading the wear pattern
The three numbers per tyre tell you more than how long it will last. They tell you what is wrong.
| What you see after the run | What it means | What I would change |
|---|---|---|
| Fronts worn more than rears | The car understeers and you are scrubbing the fronts | Softer front anti roll bar, less front toe out, less steering lock mid corner |
| Rears worn more than fronts | Wheelspin or a sliding rear on exit | One more click of TC1, softer rear anti roll bar, a calmer throttle |
| Inside edge worn most | Too much negative camber, or too much toe | Reduce camber a step at that axle |
| Outside edge worn most | Not enough camber. The tyre rolls onto its shoulder | Add camber a step at that axle |
| Middle worn most | Pressure too high | Lower the cold pressure |
| Both edges worn, middle fine | Pressure too low | Raise the cold pressure |
| One front much worse | The track loads that corner, for example a long right hander | Normal. Check the pressure on that tyre is in the window |
Change one thing, then repeat the same 4 or 5 lap run and compare. If you want to see where on the lap the tyre is working hardest, the ACC MoTeC guide shows how to log tyre temperatures.
What wears the tyres, and what saves them
Driving
A tyre wears when it slides across the road instead of rolling on it. Everything else follows from that.
- Exit wheelspin is the big one for the rears. Squeeze the throttle. If the TC is cutting in on every exit, the rear tyres are paying for it.
- Too much steering is the big one for the fronts. When the car pushes mid corner, more lock only drags the tyre sideways. Unwind and wait.
- Lockups flat spot the tyre. You feel it as a vibration, and it stays until you change the set.
- The first laps on a new set matter. Bring the tyres in over two laps instead of attacking from the pit exit.
In a real race car it is the same. The drivers who are fast at the end of a stint are the ones who looked slow at the start of it.
Setup
- Pressures in the window, always. A tyre outside it wears unevenly and overheats.
- Toe drags the tyre a little all the way down every straight. If one axle wears too fast, take some toe out there.
- Camber should come from the temperature spread across the tyre, not from a feeling. Too much and the inside edge goes first.
- Anti roll bars: soften the end that is wearing. It also helps the balance, which I cover in how to fix understeer and oversteer in ACC.
- TC1 one click higher costs very little time and saves the rears over a stint.
Tyre wear by race length
| Race length | What tyre wear means for you |
|---|---|
| 20 to 30 minute sprint | Wear will not decide it. Heat will. Keep the tyres in the temperature window |
| 60 minute race, one stop | You change tyres at the stop. Look after the rears for the last 15 minutes of each stint |
| Endurance, full fuel stints | Now it matters. The balance moves through the stint, so set the car up for the middle of it |
| Endurance, limited tyre sets | You may have to double stint a set. Find out in practice what the car is like on old tyres |
For anything longer than a sprint, the tyre choice is part of the pit stop. You can pick the set and the pressures from the MFD before you come in. The ACC pit stop guide has the steps, and the bigger picture is in ACC race strategy tips.
One more thing about sets. ACC remembers the wear on each set across a race weekend. The set you used in qualifying is not new when the race starts. Check which set you are starting on.
FAQ
How long do tyres last in ACC?
A set of slicks will do a full fuel stint of about an hour in most GT3 cars if you look after it. It gets slower through the stint, but it does not fall off a cliff unless you overheat it.
How do I check tyre wear in ACC?
Go back to the pits and open the tyre page of the setup screen. It shows the tread depth in millimetres for the inside, middle and outside of each tyre.
How much tread does a new ACC tyre have?
3 mm. The game shows wear as the tread that is left, so a tyre reading 2.50 mm has lost half a millimetre.
Why do my tyres go off after 10 minutes in ACC?
That is heat, not wear. Check that the hot pressures are 26.0 to 27.0 psi and the temperatures are under about 90°C. Sliding the car in the first laps is the usual cause.
Do new tyres have the most grip in ACC?
Not on the very first lap. A new set needs a lap or two to scrub in. After that it is at its best.
Does tyre wear carry over between sessions in ACC?
Yes. Each tyre set keeps its wear across the weekend. If you qualify on set 1 and start the race on it, it is already used.
Which setup changes reduce tyre wear in ACC?
Pressures in the window first. Then less toe and a softer anti roll bar at the axle that wears fastest, camber set from tyre temperatures and one more click of TC1.