First off, I want to start by saying how much I am enjoying the GT1 Ford since the tire update, it has become my go to car for single player racing lately. And at the same time, the tire update seems to have caused a problem for the AI, in that they are underestimating the tire wear for the race at X3 tire wear in a 30 min race with a mandatory pitstop. Right off the top of my head on Mid-Ohio raceway, I was in 4th battling for first and the other three cars pitted on the last lap, when they could have finished 1st, 2nd and 3rd in front of me. And just now, on Raceroom raceway national, 17 cars of a 22 car grid pitted twice, p1 and p2 on the 3rd to last and 2nd to last laps respectively. I am running the AI at 94%. Otherwise the AI are outstanding, battling for position and respectful at the same time, and making all the normal mistakes I see in the FIA and IMSA vids all the time, great fun, I love it. Just thought you should know, and yes it is somewhat annoying but not race ruining.
I thought GT1s are still on old tyres (v1 according to the list)? Strange pitting behaviour seems to be a more general problem with the AI, would indeed be great to get that fixed.
Thought I'd add this to the post. I just finished a race at Hungaro ring, and as much a really enjoyed the challenge of the race with the same setting as above, I had three flats on the front right tire. So, I was constantly battling for position, I went from 9th to last after a fender fight got me my first flat on the second lap just past the pit entrance. 17 minutes into the race I got my second flat. luckily it was near the end of the lap, and I was planning to pit then anyway, the tires were near 50%, and my last flat happened at t1 on the cool down lap, and my tires were around 78%. I know Hungaro is an old rough track, but more than half the AI pitted 3 times, seems a bit extreme. Like I said, it was a fun race. When you realize everything is going wrong, and the only thing you can do is enjoy the battles for position and finish the race. All in all, I finished in p6 because the ai kept pitting. Probably with flat tires