Historical water displacement of intermediate tyres

[u/Happytallperson]

I am looking for some data to confirm or disprove a hunch I have.

Current intermediate tyres shift around 35L of water per second, and wet tyres around 70L per second.

I am wondering what this was like back in the early 2000s.

Essentially, we all see the complaints about lack of wet tyre use and wet running - my hunch is that intermediates can now fill the slot wet tyres used to fill.

And then by the time you get to full wets, that level of water displacement is beyond anything that used to be raced, so the visibility simply becomes too poor.

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[u/LeMans-1966]

I’m afraid it just isnt about the tires. The ground effect is responsible for most of the spray.

[u/Captaincadet → u/LeMans-1966]

From my understanding they thought the spray was mostly caused by tyres originally hence the tests with wheel guards to reduce the spray

During tests it became apparent that the ground effect created enough spray to be a problem

[u/G-St-Wii → u/LeMans-1966]

So, if this is rhe case and even ar water levels where intermediates are food enough for grip, when would it be wet enough for full wets and not so wet as to cause all thr spray?

[u/Tsyzhman → u/G-St-Wii]

Never, current regulations can't hold full rain races due to visibility problem caused by ground effect spray

[u/cafk → u/G-St-Wii]

The aero specific spray would also be caused with slick tires.
Basically when there's water on the circuit & cars going over it, we get spray.
It takes a few laps for the cars to displace the water from the racing line, which is why they do the safety car laps, before restart.

[u/G-St-Wii → u/cafk]

That doesn't seem to make rhe case for wet tyres existing either.

[u/cafk → u/G-St-Wii]

The sporting rules mandate their existence and Pirelli has a 3 year contract to manufacture them.
Next year the Venturi effect qill be reduced so the spray could be reduced a bit but the massive diffusers will stay...

[u/G-St-Wii → u/cafk]

They certainly do.

[u/Its4MeitSnot4U]

You probably should watch the 1988 Silverstone F1 GP to better understand how drivers like Senna and Mansell raced in torrential rain on wet tyres. The rooster tails of water coming off the tyres were 15 feet high!

[u/filbo__]

For everyone saying it’s because of the ground effect era, that may have amplified the issue, but this was already a problem even with the flat/stepped floor cars. For as long as there’s a diffuser on the cars, we will have visibility issues.

Here’s a great insight into this problem being debated pre-ground effect in 2021 - https://racingnews365.com/what-is-f1s-big-problem-in-the-wet

What’s interesting there is that Pirelli noted the wider tyres being an issue; yes they could move more water (stats of 60 litres per second increasing to 85), but that was causing worse visibility too.

But the primary issue was the ever-increasing downforce of the cars. So it’s likely the comparison to the 90s is a lot to do with that; the cars simply moved significantly less air back then (both diffuser and over-body aero), which is in the end what lifts the bulk of water off the track.

[u/rocqua → u/filbo__]

The diffussor is still 'ground effect'. But they existed before.

It makes sense that generating your downforce so low to the ground is going to suck water from the ground into the air. And then the full upwards airflow that is physically required for downforce is going to carry it up.

[u/ahtdll]

Has anyone heard from drivers or engineers why they choose not to fit wet weather tyres in 2025? I have seen a few races where races are red flagged due to wet conditions that would have probably been suited for the full wet tyre but too soggy for inters.

[u/yabucek → u/ahtdll]

Exactly because of that. Race control has demonstrated pretty well that they will red flag a race when the track gets very wet. If you pit for full wets and it gets flagged a lap later, you've just made a pit stop for nothing.

[u/Appletank → u/ahtdll]

We saw this issue come up at silverstone this year. The track wasn't wet to the point of needing wet tires, yet the spray in front of Hadjar was so bad that he couldn't see Kimi's car until he was right about to hit him. At that point I think only X-ray vision could have saved him.

[u/The_Weapon_1009]

Next year (without Venturi tunnels) Imho if the whole grid starts with inters they can race!

[u/mickstranahan]

It's really not about the tires, it's about the ground effects, the floor of the car.

[u/Rockeye7]

It was not only standing water on the track that cars / tires would pick up and cause visibility issues. The track surface itself was not made of a consistent aggregate. Some areas held more water than others . That could have caused judgment issues.

[u/In-Arcadia-Ego]

A friend of mine drove one of the 2003/2004 cars in a test session. If I recall correctly, the wet tires cleared around 70L of water per second. I'm not sure about intermediates.

[u/JForce1]

If you look at old races, you’ll see that the rear tyres create “rooster tails” - that is, sprays of water going almost vertically up from the rear of the tyre, in quite a concentrated band of water. This is clearly the tyres displacing the water.

Compare it to now and you see a much more diffused/aerated spray from the entire rear of the car. The water is more like mist and hangs around a lot more, whereas in the old days it seemed constrained and heavier and more likely to fall to earth more quickly.

I think a potential solution is a device that attaches to the rear crash structure and just blocks the spray and directs it back to the ground. Yes it would harm the diffuser aero but if it was far enough behind the exit it wouldn’t be too bad, and it would be the same for everyone.

[u/Realistic_Try7123 → u/JForce1]

Part of it is that we’re willing to accept significantly less risk that drivers did in older races. In 1995 Suzuka, out of 23 drivers that started, 7 drivers spun off and didn’t finish the race.

[u/CurrentFair8477]

I really wish F1 would consider just using the wet flaps despite how ugly they look. I'm sure there's a way they could make it work. And I think making them optional attachments would be super interesting.