So, full disclosure, I posted this exact same content over at RaceDepartment (see here for full thread: Tire pressure questions), but I figured I might get more Automobilista-minded eyeballs on it over here. Here is the post: I have had great success with the old "load the car in time trial; go to the track; hit Esc as soon as AI hands over control; check temps in garage" trick across multiple cars, but I've run into some questions regarding the F-Vintage pressures. Taking the F-Trainer Novice as an example, using the time trial trick above, I come up with ideal pressures of 20.3 psi in all four tires. I've got a pretty good Brands Hatch Indy setup dialed in. I hit the track in this setup, turn a good number of consistent quick laps, then return to garage and check the pressures - I'm satisfied to see that all four tires are right in the 20.3 psi ballpark (+/- a tenth of a psi here and there). Also, wouldn't you know it but all four tires also have really nice heat distribution (hottest on the inner, coolest on the outer, middle right smack in the middle - and not too much temperature differential between hottest and coolest). My confusion comes in now on the F-Vintage. Using the time trial trick on the two different '67 models, I get the following "ideal" readings: '67 V8 - 29.5 Front, 30.3 Rear '67 V12 - 28.6 Front, 29.5 Rear It seems very plausible that the 2 different models would have different ideal pressures. The difference between front and rear pressures isn't really surprising to me either, as I don't think this is particularly unusual. So, I set to work creating setups for both cars at Johannesburg and, without too much trouble, I come up with a setup for each car that gets me in the ballpark of these pressures. But now a bit of confusion sets in - going back to the F-Trainer Novice example, hot lapping with default pressures vs hot lapping with track-specific ideal pressures was like flipping a switch. I was instantly laying down significantly faster laptimes and noticing all sorts of desirable behaviors (e.g. going flat out where I previously needed to lift, etc). I have had very like experiences across numerous other cars (like the Boxer and F-Retro). But with the F-Vintage '67 models, it feels like I'm all over the place - in some ways, they seem to actually feel/perform *worse* with the ideal pressures than the defaults. My suspicion is further enhanced by checking the pressures in the garage after a good number of consistent laps - the tire pressures are right in the ballparks of the ideals, but the temps seem to be all over the place. There doesn't really seem to be a consistent pattern across all four tires, but in a lot of cases I'm seeing the middle temps being the hottest (which would seem to indicate over-inflation...at least in a modern tire, it would). Two theories: (1) The "ideals" for these F-Vintage '67's as obtained via the time trial trick are off and I need to be a big boy and figure out some tire pressures via some old-fashioned trial and error experimentation. (2) 60's ply bias tires are different beasts and shouldn't be expected to exhibit the predictable temp profiles I've come to rely on for modern tires. The observed inconsistencies in laptimes are a function of these being some of the trickiest (if not *the* trickiest) cars in the sim and me being a terrible driver.
