How low profile and wide tires would go if rules allowed it?

[g-force_addict]

I remember a Top Gear episode where low profile tires actually made the car slower.
So how low would tire profiles go if rules allowed everything?
I guess you need certain sidewall height for deflection to increase contact patch.

Now about tires
Wider tires mean more grip, but, up to a point? Is there a limit when wider tires actually decrease mechanical grip?
Would we see road roller tire width?
Of course wider tires hinder aerodynamics and may create more rolling resistance.

[Jersey Tom]

They would go until it would slow the car down. Impossible for me to even speculate at what point that would be - both with width (particularly as you mention for creating drag and lift) and with wheel size.

[Tim.Wright]

I have always suspected, but never done the maths prove, that wider tyres will generally give more grip but at the expense of response because your yaw damping would also increase.

Tim

[Greg Locock]

In F1 you'd probably see sidewall heights reduce, perhaps even to the extent that the springs become important again. I doubt you'd go anywhere near as ludicrous as current road tires.

The tradeoff of width/'mu'/life/aero is quite interesting, and with the exception of life a directly relevant study could be done in Lapsim. So why don't you do that?

[Tim.Wright]

You are talking about Bosch lapsim? How does the tyre model take width into account? The rrason I ask is for my own project car. I have chosen tyre sizes based on statistics from other sports cars, so Im interested to hear if there is a more objective way to do it given I have no tyre data available.

Tim

[Jersey Tom]

I have chosen tyre sizes based on statistics from other sports cars, so Im interested to hear if there is a more objective way to do it given I have no tyre data available.

Two tires of the same size can be night and day different in and of themselves. I'd say good luck!

There has been work done in the past regarding some studies into tire construction parameters and effects though. Might give a very coarse idea of what's doing what.

E.g SAE Paper 760732. Gotta dig in the crates for these things sometimes.

[Greg Locock]

If you measure enough tires, and spend a lot of time, you can draw broad trends. At work I have a physics based spreadsheet that claims to estimate the effect of small changes in dimension and large changes in air pressure on the Pacejka model, and has been refined against Flattrac data for 200 different tires.

Alternatively you can look at the effect of fitting say 2 identical tires on each corner, see the effect on 'mu', ie max Fy/Fz at the Fz's of interest, and draw a straight line to give a relationship between tire and mu and so on. That would be my first course of action. If you can think of a good way of estimating the performance of a 150% width tire then you might be on to something very worthwhile.

You'll also need to build an aero model for F1 modelling, mine has 5 components, body, front wheels, rear wheels, front wing rear wing. Each has CdA, and ClA on each axle.

[The FOZ]

The greater the volume for air inside a tire, the greater the pressure changes as a result of temperature variation, and the slower the tire pressure is to react to temperature changes.

Low profile tires would reduce volume, ostensibly making tire management easier and more predictable for drivers and teams.

Something to be keen for, given this season's tire lottery.

[piast9]

The greater the volume for air inside a tire, the greater the pressure changes as a result of temperature variation

Could you elaborate on this? It contradicts the ideal gas law which is met by most gases at about atmospheric pressure.

Edit:
OK, I think I got it. In low profile tyre the pressure rises the same but it causes less deformation of the tyre as smaller increase in diameter is enough to compensate for gas pressure change.

[Tommy Cookers]

lately my TV has reminded me that 20-30 years ago F1 cars had very wide (hence low profile) tyres, and looked like toads

wasn't this increase in contact area to lower the stresses (to allow very grippy compounds that were relatively weak)
presumably this would still apply today, but for the 'road-relevant' F1 rules ?

too low a profile (some road cars) dangerously shortens contact patch and has misunderstood F1 ?
(but keeps the brake designer happy)

if F1 tyres went wider would compounds generally soften, ie would today's option compound become tomorrow's prime etc ?

[Greg Locock]

Yes, in a kinda sorta sense, the wider the tire the softer the compound and the greater the 'mu', for a given life, for a given OD.

[riff_raff]

GTP sports car tires are a good example. With their liberal regulations, they have gotten very large in diameter and wide, with very low sidewall heights. F1 tires look the way they do because of regulations.

Without limits, F1 tires would have large diameters, wide widths, and low profiles. But at some point, the drag penalty from the large tires and an open wheel chassis would limit tire size.

[n smikle]

But lets say the sizes were the same.... would the overall wheel be heavier or lighter?

[Pierce89]

GTP sports car tires are a good example. With their liberal regulations, they have gotten very large in diameter and wide, with very low sidewall heights. F1 tires look the way they do because of regulations.

Without limits, F1 tires would have large diameters, wide widths, and low profiles. But at some point, the drag penalty from the large tires and an open wheel chassis would limit tire size.

I think you mean LMP. GTP was the class the Bentley raced in the early 2000's. They were essentially closed top LMPs with narrower tires(because they had evolved from GT1 which had narrower tires than prototypes)

[thisisatest]

if the regulations were VERY open, and racing teams could work with the tire manufacturers in designing what they really want, who's to say aero wouldn't trump all as it's done in every other aspect of f1? i imagine a cross-sectional view similar to a football (american), but with the ends flattened out some for the tread. the sidewalls, coupled with the wheels, would basically form an ellipse, again truncated by the tread. there could even be small ribs or other things molded into the sidewall to help control the airflow.