For the many fans of Formula 1, tires are one of the things that's discussed by the drivers, commentators, engineers, time principals etc during every race weekend. Drivers have to adapt their driving style to extract the best possible performance from the cars while ensuring that their tires perform according to what the team requires.
Two key words that's used regularly is wear and degradation. Both can result in a meaningful reduction in laptime but the reasons for this are very different. This article aims to explain the difference in very simple terms to better understand these concepts and to give a little insight on some of the things the drivers and engineers have to plan for during a race weekend.
This is the easy one. F1 tires are currently only manufactured by Pirelli. They are available in several different compounds and are typically referred to as Soft, Medium and Hard. The softest compounds have a temperature window of approximately 85°C to 105°C. This means that the driver must drive the car in such a way that the tires will warm up and reach this window and then they must ensure that the tires stay more or less withing this window.
F1 cars aren't stuck to road going around corners like they are on rails. They tend to slide a lot more than you think and what we see on TV doesn't convey how much of movement there actually is. This movement is essentially the driver sliding the car through corners to extract maximum performance out of the car (especially in qualifying) but this sliding causes the tire to have it's surface constantly being scraped off by the coarse tarmac of the road surface. This is tire wear and is a physical reduction of the total amount of rubber on the tire.
Since each track surface is different, the amount of rubber being scraped off will be different as well. Tracks with a very coarse surface will tend to cause the tires to wear much faster than tracks with smooth surfaces. This is generally not an issue and the tire will give a similar amount of performance until the rubber is almost completely gone. Once there's very little rubber left, the tire will lose grip mainly because there's too little rubber rubber left to hold the heat in to keep the tire within it's required temperature window. The driver will then notice a rapid reduction in grip and they must either pit for fresh tires or stand the risk of being overtaken.
If you have a brand new rubber band and left it outside in the rain/sun/cold, after a few days, you will notice that if you try to stretch the rubber band, it will most probably snap very easily. The rubber will show lots of fine cracks and won't feel as soft and pliable as when it was new. This is essentially tire degradation.
Sometimes, the tires available to a driver is too soft for the track temperature and becomes almost impossble to keep within the required window. The tires will then overheat and this causes the tires to change its phyical properties from the expected high grip levels to a level that's below par. This degradation can happen quite quickly and you will realise this is an issue for a driver when they pit far earlier than expected. Driving style and car setup can reduce this a lot which is why some drivers tend to get a lot more life out of their tires than others. This also why teams tend to favour the medium tires in the race and the softs for qualifying.
Tire wear is the tire being scraped by the road surface and tire degradation is the tire rubber changing it's physical properties due to changes in temperature. Both can generally be managed by the driver and their engineer but only up to a point. After that, a pit stop for fresh tires will be needed. Hopefully this helps you have a better understanding of how F1 tires work and what the drivers and engineers have to plan and manage during the course of a race weekend.