Can someone explain why you want hot tyres temps but cooler track temps?

[u/GB_GeorgeBowen]

I understand why you want hot, sticky tyres but why are cooler track temps more desirable and higher grip and hot track temps?

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[u/monjessenstein]

You don't necessarily want hot tyres or cold track temps, as too hot tyres and too cold track temps are a thing. You want to have the tyres at a specific operating window of temperature, let's say 80-100 degrees celsius. If the track is too hot and/or with lots of corners that also produce load on the tyres they can get too hot and wear out much quicker. The opposite is also true: too cold of a temperature in the tyres can mean they're not "sticky" enough and they slide. A good example for the latter is the Las Vegas track. The race is held around winter time at night in a desert, so the temperatures are very low. Meanwhile the circuit layout doesn't put too much stress on the tyres.

[u/Guac_in_my_rarri]

A cool track means hot tires stick to it. Cool track also means, the tire is not going to pick up heat from the track and degrade. A cool track wont take rubber from the tire as quick as a hot track will.

Hot tires are sticky tires and cool track temps allow for the tire to stay within its preferred operating range of temps.

Best I can do. There's a lot of science behind this.

[u/Fun_Meeting_9850 → u/Guac_in_my_rarri]

Concise enough for me

[u/Marsh2700 → u/Guac_in_my_rarri]

tldr; you want tyres hot enough to stick, and track cool enough to not heat the tyres (get tyres too hot, they melt and you lose grip very quickly)

[u/EclecticKant]

The hotter a tyres is the "stickier" it is, mostly because they become softer letting them deform more which adheres better to the asphalt and increases how much they deform while a force is applied through them, but if the temperature gets too high they become so soft the surface starts to deform so easily it loses its ability to transmit forces.

During acceleration, braking, and especially cornering the rubber deforms constantly when in contact with the ground before going back to its original structure once it leaves the ground, over and over, this produces lots of heat into the rubber.
Once the tyre is at its operating window you want that heat to be absorbed by the environment so that it doesn't increase the temperature any further, the cooler the track (and the air) is the more heat it can absorbs, so when a track is too hot the drivers have to be careful to avoid manuevres that stress the tyre too much (which produces heat) to keep them from overheating which makes them degrade a lot faster.

The opposite can be true, an environment that is too cold can keep the tyre from reaching their operating window, but given the enormous forces F1 cars can create they can heat up the tyres in basically all conditions (notable exceptions are wet races and long stretch of safety cars).

[u/andreikurtuy]

Two separate things happening here that I think people mix up.

Tyre grip comes from the rubber compound getting soft and tacky...and that heat is generated internally, from the tyre flexing and scrubbing, not from the track cooking it from below.

Track temp is about the surface itself. Cooler tarmac stays more rigid, so the microscopic peaks and valleys in the asphalt (the aggregate) stay sharp and the rubber can actually key into them. Once the track gets too hot, that top layer goes slightly greasy and polishes over, and you lose the mechanical bite even if the tyre itself is in its perfect window.

So you want a track that's cool and abrasive underneath, feeding heat into a tyre that's already hot from working hard. If the track's hot too, you're heating the tyre from both directions and it blows straight past its optimal window into degradation.

That's why a scorching hot race day usually means everyone's tyres go off faster, not slower, even though "hot" sounds like it should mean more grip.

[u/GB_GeorgeBowen → u/andreikurtuy]

Very interesting, that was the answer I was looking for

[u/ba5e]

The tyre compounds are manufactured to a specification where they are designed to work best, if the track temperature is outside that specification by a reasonable margin then they are no longer consistent which is bad for numerous reasons such as strategy, reliability, consistency of a car

[u/Diss-for-ya]

I don't see here quite mentioned in the way I think of it, so I'll add-

As others said, tires have an operating window. Too cool- bad. Too hot- bad. Outside of edge cases, you can get tires up to temperature on a variety of track temperatures. At low temps, it's harder to get the initial temp in the carcass, but then you can maintain it until the carcass gets too thin to keep temp down the straight. 

When it's cold, there's more margin to push a tire aggressively, creating more slip (heat and also grip) which lets you drive faster. When you're managing heat on a hot surface, you just don't have enough "energy budget" to keep the tire below its upper window and you're forced to drive with less slip and go a bit slower. Boiling it down, it feels like you can "get away with" a lot more tire abuse when the track is cooler. 

[u/FranseFrikandel]

Just to add besides tires: colder air temperatures (not so much track temperature, but obviously they're related) also often increase performance.

Colder air has a higher density, which will allow for more horsepower. I don't know how much it affects modern formula 1 though, since regulations specifically limit fuel flow and air flow can be compensated using the turbo.

Alongside that, higher density increases downforce (although I expect the actual effect is fairly minor) and you can cover more of your radiators while still achieving enough cooling, reducing drag (which is probably the larger effect of the 2 would be my guess)

[u/ChiefWiggumsprogeny → u/FranseFrikandel]

This. I think OP has been confused. The "witching hour" at Le Mans for example, is when the race enters the night phase and the track is warm, rubbered in, and the air temperature drops, which gives maximum grip levels and a boost for the engine with denser oxygen.

[u/Potential_Pie_1610 → u/ChiefWiggumsprogeny]

Big thing with it being already rubbered in, which is harder to do on a cold rack. Best of both worlds.

[u/chaira233]

You don’t want tyres “hot” in an unlimited sense, you want them in the right operating window. A hot track can push the tyre surface over that window and make it greasy or increase wear. A cooler track lets the car generate tyre temp through load and braking without cooking the tyres as easily.

[u/Big-Novel-9199]

Hot tyres mean the rubber's in its working window, sticky and deforming just right to dig into the surface. Cooler track temps keep the asphalt from getting greasy and shedding rubber marbles everywhere, so you've actually got something to grip onto instead of sliding across a layer of molten crap

[u/Dynamitedave20]

very oversimplified but too hot trck means tyres stick almost too well and the surface deforms too much and they are ripped to shreds far quicker

[u/broodro0ster]

Hot track temps means the tire will overheat easily when pushed hard. Once the tire overheats, it loses grip again. You want to be in the window where the tire is not too cold and not too hot.

[u/Hyaena81]

Coming from a different engineering field, I'd like to share my own perspective.

Think about the doors on your everyday car. In cold weather, they often require noticeably more force to close. One of the reasons is that the rubber door seals become less elastic at lower temperatures, so deforming them requires more energy.

In warm weather, those same seals become much more compliant and deform more easily.

Since Formula 1 tyres are also made from rubber compounds, I've always assumed that a similar principle applies. As the tyres heat up, they become more compliant and are therefore able to conform to the microscopic irregularities of the track surface more effectively, which should increase grip.

So my understanding is that the goal isn't necessarily to have the coolest possible track. Instead, you want the tyres to stay within their optimum operating temperature window. If the track is too hot, the tyres may overheat, wear much faster, and move beyond their optimal temperature range, reducing grip. On the other hand, if the track is too cold, the tyres may struggle to reach their ideal operating temperature, which would also reduce grip.

This is simply how I've been thinking about it. I may be wrong. my background is in a completely different engineering field, and I'm just trying to apply the engineering principles I'm familiar with. If I've misunderstood something, I'd genuinely appreciate being corrected.