Question number one in the aftermath of the British Grand Prix is: Can the Pirelli tyres that have been used so far this year be raced on again? The answer is no.
The problem was something that has happened to most people in the world - the tyres were getting punctures. But the effect of them was to cause the tyres to disintegrate. At more than 100mph, that's a serious problem.
The current tyres are too critical and something needs to be done.
The tyres were changed slightly for Silverstone, with Pirelli introducing a stronger bonding process between the tread and the carcass in an attempt to prevent the tyre failures that had already happened at several races this season.
It would be easy to assume that the stronger bonding has changed the mode of failure - ie, that the same failures were happening in the tyre, but because there was a better bond between the tread and the carcass, the whole tyre came apart rather than the tread stripping off the tyre.
That might be the case, but I don't think it was. I don't see why the glue would make the tyre puncture. The tyres were tearing themselves apart because they were deflating. It went flat and then shredded. Previously, the tyres were not being punctured - with the exception of one failure on Felipe Massa's Ferrari in Bahrain, they stayed inflated.
So I believe what was happening was a different problem to before. Which is just as concerning.
There were seven races before Silverstone and we did not see this specific problem. But at a lot of races this season we have seen delaminations, where a cut in the rubber leads to the tread being thrown off.
So it seems the focus on changing the glue was necessary - but now they have a different problem.
In my view, the problems earlier in the season were safety issues, even though Pirelli said they were not.
Having the tyre deflate is not a nice thing for a driver, but having the left rear corner torn apart by the tyre delaminating - as happened to Lewis Hamilton in Bahrain - is not good either.
So there has always been a safety issue this year. There has been a problem with this tyre all year in one way or another. And it needs to be fixed.
WHAT IS THE SOLUTION?
An F1 tyre's sidewall and shoulder - between the vertical sidewall and the horizontal tread - have to do a huge amount of flexing.
If you saw a film of what a tyre does through a corner, you would walk away from the picture it is so alarming. The outside is pulled horrendously tight and the inside is bent like a double S-shape.
There is clearly a problem with the tyre that needs solving, but the solution to this issue also involves circuit design.
After the race, I went out to Aintree corner - the flat-out kink before the straight on which Hamilton's tyre failed in the grand prix - to look at the inside kerbs, which the drivers run over.
The kerb's top surface is fine, but if the driver cuts the corner a tiny bit more than usual, the inside shoulder of the tyre will go over the edge of the kerb and that is about 30-40mm high and at a 90-degree edge with a radius of 2-3mm. At F1 speeds, that is a sharp edge.
Those corners are kinks, so the inside wheel will be slipping and spinning. The inside shoulder will be pulled tight and under great stress, so the kerb edge is acting like a knife on that shoulder. It may not cut it through, but it will certainly damage it.
A Pirelli engineer went out to look at both that corner and Chapel, the one on to the Hangar Straight, where Jean-Eric Vergne and Sergio Perez had their failures, and saw a similar issue.
The tyre should be strong enough to withstand that but clearly these Pirellis are not, so something has to be done - both with the tyre and the kerb.
It will be very difficult for a tyre manufacturer to recover this by Germany at the weekend. But they may have a big batch of last year's tyres sitting there. They may also have a batch of the tyre they wanted to introduce for Silverstone and which was briefly tested in Canada - which is basically last year's construction with this year's compounds.
If there aren't enough for a full allocation, then they just have to give the teams what they've got and say "do the best you can".
In addition, the FIA should go to Germany and look at all the apex kerbs. If they identify similar ones to Silverstone, they can chamfer them to 45 degrees (remove the sharp edge), which would immediately alleviate the problem.
Going forward, the specification of those kerbs is defined by the FIA - and that spec should change, without doubt, because that would alleviate the problem for any tyre.
THE RULES ARE A PROBLEM
There were none of these problems last year. Earlier this year, after the delaminations in Bahrain, Pirelli wanted to reintroduce last year's tyre, which had a tougher sidewall, and a Kevlar rather than steel belt - the material that runs around the circumference of the tyre under the tread.
But it was not allowed because of the rule that says the tyre specification can only be changed during the season if there is a safety issue.
Understandably, Pirelli did not want to say publicly that there was a safety issue - that's bad for its marketing. But it tried to do the right thing in the best way it could, by running tests to try to come up with a new design.
A huge issue blew up about the 'secret' Mercedes test with the 2013 car and so on, and people lost focus of the fact that the tyres were still a problem.
Engines are certified and fixed, but manufacturers are allowed to change them to solve reliability problems. Why shouldn't the same apply to Pirelli?
This is a safety issue but it's also a reliability issue. Pirelli should be able to say that and get something done.
TOO MUCH TALKING, NOT ENOUGH ACTION
There is so much hot air in the paddock, from all the teams. They talk and talk and nothing happens.
But they need to react to this situation and simplify the rules. I have been involved in this sport for 41 years and I am fed up of listening to pure waffle from a bunch of people who are supposed to be intelligent.
I see McLaren team principal Martin Whitmarsh has said there is a "danger" of a boycott of the German Grand Prix this weekend. This is the sort of thing I'm talking about.
The best thing Whitmarsh can do is go and hide. Silverstone was another terrible race for McLaren and it's in their interests to get the rest of the season cancelled so they stop embarrassing themselves.
What is the point in saying that? It's ridiculous.
In 2005, Michelin had to pull out of the US Grand Prix because of a tyre issue. That could have been avoided if certain people in power had made different decisions - among them the current FIA president, Jean Todt, who was then team boss of Ferrari, and the then-president of the FIA, Max Mosley.
If there had been 10 tyre failures at Silverstone on Friday morning, would we have not had the grand prix? I would certainly hope not. I would have thought people would get their heads together and sort it out.
There has to be a grand prix. And there will be. Pirelli will take the best tyres they have for the situation and if some of the teams don't like them they can sit in the garage.
Pirelli's F1 engineers need to clear their heads, do what they can for Germany and Hungary, and put a big plan in place for the Belgian Grand Prix at the end of August. Spa-Francorchamps is even more critical for tyres than Silverstone. They need a new tyre, with new construction, revising it in whatever way they want.
Meanwhile, the FIA needs to chamfer the kerbs so the tyres are not as under stress as they are now. That will eliminate the problem - and if they think that's not possible I have some mates who can come and do it for them in a few minutes.