Make a wheelホイールを作る

In the car's looks file assets/mypack/vehicles/<car>.json, set the model and texture under wheel, and write the radius you built at as designWheelRadius (outside wheel, at the top level):

{
  "body":  { "model": "mypack:models/entity/my_car.obj",
             "texture": "mypack:textures/entity/my_car.png" },
  "wheel": { "model": "mypack:models/entity/my_wheel.obj",
             "texture": "mypack:textures/entity/my_wheel.png" },
  "designWheelRadius": 0.45
}

The rest of this file is in chapter 6 of the Car guide.

Any size is fine. Write the radius you built at (in m) as designWheelRadius when fitting it to a car, or as designRadius when making it a part (chapter 2). The game scales the mesh by the ratio between this value and the car's tyre radius.

Change the tyre radius in the in-game tuning screen and the model follows: the tyres stay on the ground and the body rises (a lift-up).

Build only the rim and KurumaMod's own tyre is fitted automatically. To borrow the whole wheel, use kurumamod:models/entity/wheel.obj as the model and kurumamod:textures/entity/wheel.png as the texture (chapter 6 of the Car guide).

When a tyre (chapter 3) is picked in the parts screen, the game hides any object whose name starts with tire (in any case) and draws the picked tyre on the rim instead.

• With no tyre picked (Normal), your own tyre is drawn as it is
• Without the name, your tyre stays part of the wheel and shows through the picked one
• With shader packs, only the tyre casts a shadow, so no spoke pattern appears on the ground

• Wheels too big or too small — designWheelRadius (or designRadius for a part) is not the radius you built at
• Wobbles as it spins, sinks into the ground, or floats — the origin is not at the axle centre. Check it is not at the bottom of the tyre
• Rolls on its side — the spin axis does not run left–right (X). Rotate with R Y 9 0
• The right-hand wheels face inward — the face is not towards +X. Rebuild it as the left-hand wheel (the mod mirrors it for the right)
• Two tyres drawn in one place — you modelled both sides. Keep only the left-hand one
• Your tyre shows through the picked one — the tyre object's name does not start with tire
• Everything is white — no .mtl, or no material. Harmless if the shape is right (colouring is in chapter 4 of the Car guide)

Write them under wheel in the looks file assets/mypack/car_parts/my_wheel.json. They become where the parts-screen sliders start, and "R" returns to them.

{
  "wheel": {
    "model": "mypack:models/entity/my_wheel.obj",
    "texture": "mypack:textures/entity/my_wheel.png",
    "designRadius": 0.45,
    "offset": [0.02, 0.0, 0.0],
    "scale": [1.3, 1.0, 1.0],
    "camber": -4.0
  }
}

• offset — only X is used: how far out to push the wheel [m] (−0.05 to 0.10)
• scale — only X is used: width multiplier (0.5 to 2.5). Leave Y and Z at 1.0 (changing them breaks ground contact)
• camber — camber in degrees. Negative leans the top inward (−30 to 10)
• Values outside the range are clamped to the nearest end
• Anything you leave out takes the car's own wheel value

Leave out model and texture; the car's own wheel is kept and only the values you write change. The example pack's deep_dish works this way. assets/mypack/car_parts/deep_dish.json:

{
  "wheel": {
    "scale": [1.6, 1.0, 1.0],
    "camber": -12.0
  }
}

This only names something players can already make with the sliders, so usually you would build a wheel with its own mesh.

List car ids in cars in data/mypack/car_parts/my_wheel.json. The part then appears only in those cars' parts screen. Cars from other packs are fine (kurumamod:car is KurumaMod's default car).

{
  "slot": "wheel",
  "cars": ["mypack:kei", "mypack:kei_van"]
}

Add order to data/mypack/car_parts/my_wheel.json. Smaller numbers sit further left (100 if left out).

{
  "slot": "wheel",
  "order": 10
}

Not possible yet. All four wheels wear the same part.

• Not in the parts screen — the data/ file is missing, or has no slot (the log says so). If you use cars, check the car you are in is listed
• Listed, but the looks do not change — the assets/ file name differs from the data/ one, or a key inside "wheel": { ... } is misspelt
• The name shows as my_wheel — the lang key is not part.<pack>.<part>
• Too big or too small — designRadius is not the radius you built at
• Driving does not change — wheels are looks only. To change grip, make a tyre (chapter 3)

These are all the keys. Every number is a ratio to the Normal tyre, and anything left out is 1.

{
  "slot": "tire",
  "tire": {
    "stiffness": 0.85,
    "grip":    { "paved": 0.88, "dirt": 1.20, "gravel": 1.25, "sand": 1.10, "snow": 1.10 },
    "rolling": { "paved": 1.15 }
  }
}

• grip — grip on that surface
• rolling — rolling resistance on that surface. Bigger means harder to keep moving
• stiffness — how sharply force builds once you steer. Lower it for chunky tread
• Surface names: paved, dirt (dirt and grass), gravel, sand, snow, ice
• Ratios are clamped to 0.3–3.0

The shipped tyres, and what they do on the default car, for reference:

Please don't make a tyre that wins everywhere. A tyre that is good somewhere should be worse somewhere else; that is what makes the choice matter.

1. Model the tyre alone in Blender. Origin, spin axis and outer face are the same as a wheel (chapter 1). Any size will do
2. Put the OBJ and texture in your pack: assets/mypack/models/entity/my_tire.obj and assets/mypack/textures/entity/my_tire.png
3. Add the looks file assets/mypack/car_parts/my_tire.json (same file name as the part). Always write it inside "tire":

   {
     "tire": {
       "model": "mypack:models/entity/my_tire.obj",
       "texture": "mypack:textures/entity/my_tire.png"
     }
   }

The inner and outer radii are measured from the mesh, so you need not write them. The picked tyre is stretched so its inner edge sits on the wheel's rim and its outer edge at the car's tyre radius; bigger rims get thinner sidewalls. The parts screen's Width slider acts on the wheel and tyre together.

The radius where the tyre's inner edge (bead) sits is chosen in this order:

1. rimRadius in the wheel's looks file, if written (mesh units, m)
2. otherwise, the inner edge of the tyre you modelled on the wheel (Tire)
3. otherwise, 95% of the rim's outermost radius

If tyres sit wrong, add rimRadius under wheel in the wheel's looks file assets/mypack/car_parts/my_wheel.json:

{
  "wheel": {
    "model": "mypack:models/entity/my_wheel.obj",
    "texture": "mypack:textures/entity/my_wheel.png",
    "designRadius": 0.45,
    "rimRadius": 0.33
  }
}

As with wheels, cars and order go in data/mypack/car_parts/my_tire.json (chapter 2).

{
  "slot": "tire",
  "order": 30,
  "cars": ["mypack:kei"],
  "tire": { "grip": { "paved": 0.90, "gravel": 1.20 } }
}

• Listed, but drives like Normal — "tire": { ... } is missing (the log says so)
• Only some surfaces have no effect — a surface name is misspelt. Unknown names are logged and ignored
• Still looks like KurumaMod's standard tyre — the looks file is not written inside "tire": { ... }, or the assets/ file name differs from the data/ one
• The picked tyre and the wheel's own tyre overlap — the wheel's tyre object name does not start with tire (chapter 1)
• Sidewalls too thick or too thin — see "Fix where tyres sit on my own wheel" above. If that is not enough, write innerRadius / outerRadius (the mesh tyre's inner and outer radius [m]) inside the tyre's "tire"