What I mean by "bad" is that the tires are the weakest link, bad relative to the rest of the car. I could call them good, but the rest of the car excellent -- it makes no difference. My feeling, supported by nothing but Tesla's history, is that they are likely trying to improve the parts of the car that are weakest. Most of the attention up to now has been on improving the battery and range (which involved the tires a bit). Some has gone to improving quickness (which has also involved tires). But I think at this point that the way that the vehicle interacts with the driving surface is the greatest opportunity for improvement of the vehicle, so my guess is that Tesla is trying hard to do something about it, most likely something amazing that existing tire manufacturers would never do.
My guess is that it will involve active reconfiguration of the tire structure at some level, perhaps piezoelectric bands to dynamically change the tread. Also possibly new materials -- various composites and carbon fiber seem to me to be likely candidates, but I really know nothing about that sort of thing. However I do know that Tesla likes to think big, and it doesn't count on others to solve its core problems.
Tesla and SpaceX only gets involved in making their own when there is some sort of tech that Elon has determined is physically possible, but nobody is doing it, or they can't find a supplier to make what they want. Most of the automotive business is very complacent and slow to change, but that's not the case with tires. There is a lot of ongoing research by most tire makers to find the best tire formula.
About 15 years ago someone wrote a book about why Europe emerged as the dominant culture on the planet and why it wasn't someone else. He concluded that Europe had just enough competition between neighboring kingdoms to spur technological development without too much competition so there was not enough stability.
He used the example of China as a kingdom that could have dominated the world, but failed. Before the Europeans began exploring aggressively, the Chinese became the world's dominant naval power. They explored the coast of East Africa and there is some evidence a few ships made it all the way across the Pacific (stone anchors found off California).
The Rim of Fire didn't end up populated by the children of Chinese sailors because they crewed their ships with eunuchs. And just as their explorers were about the round Cape Horn and make their way towards Europe, a new emperor came into power who hated ships and scrapped the whole program, having everyone involved put to death.
When an empire is large, one idiot can kill a potentially great technology on a whim.
On the other side was India which had lots of small competing states. The borders of these states were so fluid nobody knew from year to year which monarch they were going to be beholden to next. That instability didn't allow new tech and innovation to develop.
In Europe, there was constant conflict between neighbors and the borders of Eastern European countries changed quite frequently. However, the balance between stability and competition was just right for new tech to flourish and not be lost. If an idiot monarch decided he didn't like some new tech, losing the next war would convince him of his folly.
The car business is not competitive enough. In the case of cars, there is a lot of brand loyalty and they pretty much offer the same tech on most cars. A Toyota Corolla is going to have pretty much the same feature set as other cars by other makers in the same price and size range. One may have more cup holders, but overall there isn't much difference from brand to brand.
Because of this stability and reluctance of customers to move, the pace of innovation is relatively slow and things are pretty stable. On the other hand, tires are the one area of the car business where there is a lot of competition. There are many players but a large enough market that each can make a good income selling tires to new car makers as well as replacement tires to consumers.
Tires are also one thing that can have noticeable variation and every car owner needs to buy them. Other aftermarket car items either make little difference like the brand of motor oil (again there is a lot of brand loyalty here, but there is little difference between one brand and another, looking at the same type of oil, synthetic vs natural is a different thing) or they are optional like seat covers. Tires are something everyone needs and they can vary a fair bit.
So tire makers aren't complacent. They spend a fair bit on R&D working on better tire tech. Whoever comes up with superior tech has an advantage in the marketplace for a few years until everyone else catches up.
If Tesla came up with a new idea for tires that was a tech advancement, they would find an interested and willing audience in almost any tire maker they approached. They don't want to be like the European king who passes on a new technology only to find out their neighbor has it the next time they fight one another.
As a result if Tesla has any new ideas about tires, they don't need to expend the effort to learn how to make tires, they just need to partner with a tire maker to make what they want to make.
Here is another vote for Hankook tires ... excellent performance and value
My SO's ex-husband (who is still a friend) put Hankooks on both his cars. They were the cheapest and he didn't have a lot of money, but he was very impressed with the performance. He's a bit of a motorhead (built custom motorcycles, had a classic Mercedes for a while, etc.) so if he's impressed they are definitely worth a second look.
