Wet lines are simulated yes, but only if the race starts dry and then progressively gets wetter. Apart from the normal line being slipperier due to the rubber buildup, your tyre also picks up marbles off line and this sorta gives it more "grooves" to clear the water better.
However, if the track is wet from the start (i.e. it has been raining for a while), it's faster to stick to the usual line. At this point the rubber on the normal racing line and the marbles off line has been washed off completely, so just take the normal racing line as usual to open up the corners. No extra grip to be had driving funky lines. As proven in this wet Spa TT a few months back, all of the top laps drive normal lines.
Also, I reckon the gap between inters and wets in GT is too small under full wet conditions (either that, or the track never gets to fully flooded conditions where inters are useless). Even at the 2nd bar of wetness there's only like 1-2 secs difference between inters and wets. But as soon as the track starts to dry, the wets just loses multiple seconds to the inters and degrades quickly. Combined with the accelerated weather, the inters is just a more versatile tyre overall because you'll be okay driving it anywhere from 1/3-2/3 wetness. Whereas the wets are only slightly better at 80% plus wetness (which rarely happens).
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Moving on to another topic, I'm surprised no one noticed the physics has been slightly changed with the last update. Now if you mostly drive race cars with wings and slicks, it can be hard to detect. But I drive road cars on a daily basis on the Nordschleife on my route to tune every car in the game, so I noticed a few things has changed. Initially I thought it's just placebo effect but I have also been re-doing the Master Licenses recently and it's especially noticeable on the old cars with soft suspension and on dirt/snow. Last week's Daily A (MX5 at Willow Horse Thief) also shows quite a difference in car behaviour (I was rank 180 ish at the end so I spent quite some time here and can compare before/after update).
Summarising the changes:
- Weight transfer seems to have been toned down again.
- Tyre grip loss is more progressive e.g. blending between trail braking to cornering is less severe than before, and also on comfort/sport tyres when you oversteer it's easier to hold a nice 4 wheel drift.
- The Master License with Countach at last sector of Grand Valley is prime example of this (or any old car on undulating track). Pre update the heavy rear is very hard to tame and when you do breakaway it's very snappy. Now it's more progressive and you can maintain slides better. Still tricky to drive, but not manic and OTT like before.
- The MX5 at Willow is also obvious. The first turn with a dip at the apex can unsettle the car dramatically pre update, now it's less severe. Also coming out of all those 2nd gear hairpins it's very easy to induce oversteer before, now you can get away with a lot of throttle and if a slide does occur it's much smaller.
- A lot less understeer on snow/dirt. I suspected something changed when I did the Urus weekly challenge, but put it down to the SUV being exceptionally good offroad. Then I redid the snow license (Celica at last sector Lake Louise) and it's so easy to rotate the car now. No more terminal understeer, you can use scandi flicks to set up the car for corners as in real life. The car grips under acceleration and actually moves forward instead of just pinging off the rev limiter.
Now the bad part: I feel like the FFB has been toned down again. For reference I'm using T-GT, FFB Torque 3, FFB Sens 1. Road feel seems to be less detailed and there's a lot of centering spring feel. Tried increasing FFB Sens but it doesn't do much (seriously, I have never detected any difference with this setting between 1-10). It's not as numb as GT Sport, but pre update it was the best GT's FFB has gotten. Now it's kinda meh again. The cynic in me feels this is due to the new Fanatec GT DD Extreme's FullForce implementation and PD trying to get people to upgrade by nerfing FFB with other wheels. Or (more likely) the new more sedate suspension physics have muted the road feel. Either way, as people have said FFB is still miles behind titles such as AC/ACC. The new physics is a step in the right direction, but PD really need to get a leg up on FFB (and give us more adjustment sliders) in GT8.
Just my 2 cents. Maybe it's all just in my head but as a "road car specialist" some of the behaviour pre and post update are quite stark. I did drive a few Gr.3/4 and the GT-One TT (2 secs off top time, for reference), and the changes are much harder to detect with these stiffly sprung high grip cars. It's there, but only if you already know what to look for. If I only drive race cars (like a lot of people here) I probably would have missed the changes.