Mvez

For sure.

I watch my tire temps come up, and the rears always take longer to come in than the fronts. Even on Cup2, I sacrifice grip for cold temp support, and go out higher and run Cup2 at 35-38 hot rear. I don't start leaning on them until they get to 32-33. Although the RWS always loads them up, the majority of the wear comes early while the tire is still lower in pressure and rolls more. I've gotten closer to 5-6 days out of my tires this way, assuming about 4-5 heat cycles per day.

You cannot have your cake and eat it to with this car. Ultimate performance comes with sacrifice, unless RWS is removed and then you get more "traditional" tire wear.

I've run my rear original Cup2's at -2.8 to -3 their entire life, and I have some outside wear, but almost identical or more inside wear from driving 1:45 to and from the track. Fronts at -3.2 to -3.5 corded inside shoulder. I think the sweet spot for rear camber is somewhere in between -2.5 and -3. As much as my brain tells me not to because of understeer, I'm considering running -2.8 to -3 all around to see how it works on my new set of Trofeo-R.

orthojoe

yes

MaxLTV

Why would it do that? (toe scrub, that is)

Mvez

On track, at speed, the wheels are turning in the same direction as the front wheels (except in really slow corners less than 30mph), so they pre-load the rear tire, which is great for stability, but the loading up of the rear tire is constantly scrubbing the outside shoulder, no different than how the front tires scrub on turning. Add to that it's a rear engine platform with lots of weight on the rear, and you have a recipe for heavy tire shoulder wear.

Not to mention, the car also grabs a little inside rear brake on entry (PTV) which has the further small effect of loading the outside tire a bit more.

It all works pretty brilliantly, but at a price.

orthojoe

^yup. Exactly

Mvez

I also think this issue is more exaggerated with a non-RS because at lower speeds and with cold pressures the regular GT3 doesn't have the rake the RS does, which helps it turn a lot better (along with 265). When I run my DH, which have a 1" taller rear tire than front (similar to RS rake), the car turns much better. The GT3 inherently has more understeer.

At higher speeds the RS loads the rear tire more due to more downforce, so it in theory should pick up more rear scrub than the GT3 at higher speeds.

It's tricky.....tricky, tricky, tricky.....

TRAKCAR

^^^ Thanks guys ^^^

My theorie is that I can start higher, give up the laps where Dunlops are low PSI until they come up and only then lean on them because they will stay decent very hot.

MPSC you have to start much lower because they turn to snot above 34PSi and but they are slow after lap 4 no matter what.
So to get a hero lap out of them you have to make it happen on laps 2 or 3 on either too low PSI or they will be really completely undrivable the rest of the session.

Better would be to come in and bleed, but why wants to stop in a short session..

So by the theorie (I think correct) that most outer rear tire wear happens when you push on cold tires, then the Dunlops should last longer.

Mech33

Why does increased rake make it turn better?

TRAKCAR

More weight on the front, rear rotates easier.
Think Red Bull F1.

Yargk

Assuming the tires don't go too greasy at high pressure (RE-71R for GT4 or Dunlop), the other option for the first session is to start at a cold pressure that isn't calculated so that you'll hit your desired hot pressure at the end of the session. Many people seem to make a game out of "what cold pressure is perfect for the morning session to end up with the correct hot pressure." However, this means the first laps are at very low pressure. I'd think it would be preferable/safer to overshoot and have 1-2 pounds extra at the end of the first session, then bleed down so you're ready for session 2.

shizzle

Not exactly. More rake makes the underbody diffuser work better by accelerating the speed of the air under the car as it exits the rear. This creates more downforce.

mdrums

Yep you can just look at the Red Bull and see the rake.

signes

lol

0explorer

This is a true statement (no joke).

Mech33

But changes in rake should have a negligible effect on front to rear weight distribution...

I suspect you’re just changing the suspension geometry operating point when you raise the rear or lower the front, changing the dynamic behavior (e.g., camber change vs compression).