The Suzuki rider recovered from eleventh on the grid and started the race well under the top six, driving at a pace that threatened a podium finish.
But while teammate Alex Rins secured second place, Mir lost to ninth place at the checkered flag when he encountered a problem with his soft front tire.
As Quartararo wins dominantly, his championship lead over Mir is now 65 points with a preliminary six races in 2021 – which means that Mir is now defending his title is probably over.
“Yes. It is not finished before the checkered flag, that is clear. But yes, I am disappointed with today,” said Mir when asked by Autosport whether the championship was now out of reach.
Mir later asked how his title challenge ended in that position after taking just four podiums compared to Quartararo’s five wins in 2021, adding, “I honestly expected to be closer and in this one to be honest Can get more podium places this season.
“We got a couple of fourth places that couldn’t be podium places.
“But well, to be honest, I’m not really optimistic today because what happened is really strange and something that happened today is not clear to me.
“So we have to understand.”
Joan Mir, Team Suzuki MotoGP
Photo by: Gold and Goose / Motorsport Images
Before the 20 lap race at Silverstone, Mir made a late change of the soft front tire on the grid as the cooler conditions forced a number of drivers to do the same.
But the Suzuki rider doesn’t think his front tire problems have anything to do with the softer rubber, as Quartararo won the race with the same option.
“Well, to be honest, the feelings were really good in the first few laps,” he explained.
“I was able to drive well and at the end of the race I was in the position I wanted.
“But I had a problem with the front tire. This problem caused me to lose two or three seconds in the last five laps and quite a bit from 10 laps to the end, or 12.
“I had this problem that I didn’t have before and we need to understand it.
“I went with the switch.
“Well, I’m not sure it’s a tire choice issue because the winner used this tire and I was able to work a lot on this tire and nothing like this has ever happened to me. So we have to understand. “