Eli5 – F1 cars have smooth tyres for grip yet on a normal car this would be certain death. Why do smooth tyres give F1 cars more grip yet normal cars less grip?
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All tires are engineered down to the chemical level in modern vehicles. F1 tires are probably the most expensive on a per-tire basis because that’s where the cutting edge is in tires.
The example I’ll use is top fuel dragsters. If you don’t know about them, [watch this video](https://youtu.be/8HsCB8gdV3c) to learn more about their tires. To summarize, they require a tire with a high contact patch to hold the grip and get off the line. At the same time, they basically have no gearbox, instead the drive shaft turns so fast that the tire wall gets folded over itself, which causes tire diameter to shrink. Thus, the contact patch increases dramatically right when you need the most grip. After the, well you can’t really call it a car, gets moving, the need for grip is marginal compared to what you required for a launch. The tire wall catches up with itself and causes tire diameter to increase, which reduces the size of the contact patch once you’re moving, and reducing friction. Trust me, watch the video.
When an F1 car puts all that power to the ground with its featherweight body to hold it down, it needs a big contact patch to prevent wheelspin. If you compare F1 cars of the past decade with those of the 1950s, you’ll see that a modern rear tire is probably 4-5 times wider than what they started on. Meanwhile, the front tires are relatively skinny, because you don’t need such a huge contact patch. Of course, a lot of grip in F1 is generated by aerodynamics and down force, which is required to have enough grip to go around a corner at the limit.
While an F1 car puts up laps, the rubber in the tire is slowly rubbed off and starts to cover the track surface in a layer of rubber. This layer allows even more grip, which is an additional reason why the cars drive near the turn apex: there’s already rubber to provide grip. The tires are designed to shed material at a steady rate at specific conditions. There’s also the three tire choices per race, but that’s not what your question was about.
In wet conditions, there’s a layer of water between the tire and the surface. Friction disappears, and the water also prevents tires from getting up to safe operating temperatures. Rain tires increase the contact patch by getting rid of the slick design, and instead cut grooves for water to flow unimpeded which lets the rubber actually contact the surface without hydroplaning (basically surfing over the water, contact area is zero). On wet tracks, drivers take corners further from the apex, because that rubber layer gets very slick.
To summarize, on dry tracks F1 tires are slick to increase to contact patch with the asphalt. On wet tires they cut grooves, also for the reason of increasing the contact patch. Each tire is optimal for the conditions it is designed for.
Road tires are the same. There is no reason to use slicks on the road. If you did, you’d have to change your tires to drive in the rain. Road conditions are also not the same as tracks. Occasionally you hit that brand new patch of tarmac on the highway and it feels so smooth, that’s every inch of a controlled race track. Roads are expected to have snow and slush in winter, potholes after winter ends, rain and puddles throughout the year, manhole covers, sewage drains, etc. If a slick hit a square metal drain straight on I’d expect there to be a noticeable mark. And dirt or gravel roads wouldn’t be too fun with slicks.
In Canada everyone is recommended to have two sets of tires: all-season, and winter/snow tires. All seasons are basically a summer tire that is engineered to operate at lower temperatures. A summer tire might work great at 30C but it’s not as good as 0-10C. Winter and snow tires are noticable the moment you put them on because the road noise is much louder, but they’re designed to maximize grip on densly packed snow and on very cold road surfaces (-30 to 0). If you use summer tires, they’ll be great on a garage-kept convertible, but could really get you in trouble in the off-season. For every application and every environmental condition, there is a tire for you.
Then there’s tires for equipment besides passenger vehicles. Truck tires have to withstand max 80k lbs across all tires, so they have very different materials and construction techniques than car or F1 tires. A farm tractor needs to be able to move in loose soil, so the tires have grooves that dig in deeper to the surface than a pickup tire could. A forklift has to be able to lift pallets, so kind of like a semi tire, but it cannot damage floors inside warehouses and factories, so they often have slicker tires than you’d expect.
There is one category of road cars I can think of that do use slicks: drifters. Maybe I should say road cars. Drift machines will use slick tires on the rear wheels to ensure that they can break the wheel lock and spin them up. For this they tend to use very worn road tires, since those have low grip and they’re going to burn the rubber off until they pop anyway. I presume a competition drift car would have specialized tires, it’s a pretty well established motorsport at this point.
Tl;dr: different characteristics can accomplish the same goal, depending on conditions. Some tires are designed for carrying huge loads at extreme temperatures, while some are designed for maximum grip in perfectly controlled environments. It’s like evolution with tires, the best designs win out (especially since the bad designs wrap you around a tree)
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