Better Tyre Sidewall Comfort Calculations

Good Morning Devs! I wanted to suggest a better calculation to use for tyre comfort ratings. I see that you guys made a tyre aspect of 40 as the cutoff for comfort. This starts to become a problem when we get to wider tyres because we need to make the sidewall comically large to not get any penalties, and even more problematic for asymmetric tyre sizes (235 front 285 rear). I wanted to suggest a better calculation based on actual tyre sidewall size. Maybe something like a double asymptotic calculation:

Tyre Sidewall Actual = Tyre Width * (Aspect Ratio/100)

Tyre Sidewall Actual = x

y = -(0.4/(0.45+1.15^(x-108)))+0.5

y = Comfort Multiplier

This function will give penalties for tyre sizes below 101mm (asymptote on -0.389) and advantages above 101mm (asymptote on +0.5). I will give some real life examples:

Rolls Royce Phantom (285/45 R21)

  • Tyre Sidewall Actual = 128
  • Comfort multiplier = 0.476

Porsche Cayman (235/40 R19)

  • Tyre Sidewall Actual = 94
  • Comfort Multiplier = -0.176

Mazda 2 (185/60 R16)

  • Tyre Sidewall Actual = 112
  • Comfort Multiplier = 0.318

BMW M6 (265/40 R19 Front, 295/35 R19 Rear)

  • Tyre Sidewall Actual: 106 (107F, 104R)
  • Comfort Multiplier = 0.168

Lamborghini Aventador (255/35 R19)

  • Tyre Sidewall Actual: 89
  • Comfort Multiplier = -0.269

For asymmetric tyre sizes I would take the average of the two numbers. But because we are using Tyre Sidewall Actual, it shouldn’t be too different.

I know you guys are busy with the 4.2 update. But it may be something that could be worth considering if you have some spare time.


May I ask what do you mean by comfort factor?