Rotating an object around it's centre in OpenGL

I'm writing small 3d viewer of models from .obj file.
I have a car and I want to rotate car's wheels. I found a lot of good examples but I still have a problem: wheel rotates around point at the it's border, not around center. You can see it on the gif.
Below part of code without code for material and lighting. I find coordinates of wheel's center.

GL.PushMatrix();

// Rotate the car
GL.Translate(x, y, z); //x=0, y=0, z=0
GL.Rotate(ori, 0, 1, 0); // ori=90

// ...
// Material and lighting code 
// ...

foreach (var group in file.G)
{
    GL.PushMatrix();
    if (group.name == "wheel_rf")
    {
        float xTmp, yTmp, zTmp;
        xTmp = yTmp = zTmp = 0;
        int count = 0;
        // read group's faces
        foreach (var f in group.F)
        {
            // read face's vertices
            foreach (var v in f.V)
            {
                yTmp += v.Y;
                zTmp += v.Z;
                xTmp += v.X;
                count++;
            }
        }
        yTmp /= count;
        zTmp /= count;
        xTmp /= count;
        GL.Translate(xTmp, yTmp, zTmp);
        GL.Rotate(this.wheelAngle, 1, 0, 0);
        GL.Translate(-xTmp, -yTmp, -zTmp);
    }

    // draw faces for each group
    GL.Begin(file.PrimitiveType);
    foreach (var face in group.F)
    {
        GL.TexCoord2(face.VT[0]);
        GL.Normal3(face.VN[0]);
        GL.Vertex3(face.V[0]);

        GL.TexCoord2(face.VT[1]);
        GL.Normal3(face.VN[1]);
        GL.Vertex3(face.V[1]);

        GL.TexCoord2(face.VT[2]);
        GL.Normal3(face.VN[2]);
        GL.Vertex3(face.V[2]);
    }
    GL.End();
    GL.PopMatrix();
}
GL.PopMatrix();

Note! In first time I rotate all car on 90 degrees otherwise I would have seen the car back. I can't find reason of problem. Maybe trouble in the car model, but whole car is drawn fine.

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