85Gold

So I am researching going to 19" for track tires steel brakes car and I have a ?? about tire sizes. For the stock 265/35 20" 325/30 21" the rears are 1.7" bigger overall diameter than the fronts. If I go 19" front and rear 265/35 19" 325/30 19" the the rears overall diameter is only .4" taller vs the OEM 1.7" taller. I am concerned that this little difference is going to potentially cause issues with ABS and Stability Control running the 19's. What sayeth the RL brain trust and would like input from anybody who has actually done this not just armchair warriors please. Yes I'm sure this has already been covered but this old Boomer search skills are severely lacking

TIA

Peter

monochrom3

Good thread here: https://rennlist.com/forums/991-gt3-...019-gt3rs.html

Here are the sizes I've found that others use. I've not gone to 19" yet personally (car has PCCB currently)
265/35/19 325/30/19
295/30/19 345/30/19 (preferred)
275/345/19 325/705/19

phoneyman

Here are two resources I used when buying 19" wheels all around. I have not run them yet so no personal experience.
Apex Wheel Fitment Guide
Rennlist/Apex thread with chart for brake clearance

RE: your question about ABS/ESC/TC, I cant find the thread I've read before but IIRC the gist was "it might or might not affect the systems. Run with TC/ESC off on the track, etc. etc." I'll be testing this stuff for myself but realistically not til next year.

TRAKCAR

-Why 19"? I also always did, but I had no reason on the 991.2RS.
-PCCB and ST fit under 19" Forgelines. Scratches the top of the calipers lightly. I already sold mine, if you want to run Ferrari take-offs I guess but I don't recommend it.
-As opposed to the 991.1RS we could not make it go faster on smaller diameter tires, softer springs, etc.
-Only verified on 991.1RS, but I assume like all else it got better in the 991.2RS; Even if TC/SC aren't happy and the car is undrivable (SC turns on, just turning the wheel slightly on the straights) The car learns for 3 laps, then its drivable and just keep going after a day it never comes on again.
-Id go ST before I'd go 19".

85Gold

Need a good wet tire option for 1Lap, and Michelins suck in Nspec, Conti makes a great 19" size.

Peter

ParadiseGT3

200 tw? and one tire for everything in 1 lap, yeah? Nankang CR-S, what you gain overall in (presumably) majority dry conditions will be > than a more wet oriented 200 tw imo.

Fit the RS OE 20's. It's what I run. They're not bad in the wet, especially if just wet pavement, no depth.

85Gold

Yeah Kangs in the wet and cold which is common on 1Lap are a non starter. Also in 2024 the Kangs weren't on the approved list I guess they didn't opt in.

Ran 71RS in 2024 but on the GT4 which worked great but no big rear sizes.

Peter

e34nication

I’m running SC3R’s in 265/35/19 / 325/30/19. No issues with any systems. Mine is a 991.1 RS.

85Gold

That's the kind of feedback I need whether it works or doesn't. 👍

Peter