Il CP

I've seen two 992's set up with 265 fronts. Whether they fit or not, has to do with offset. They definitely fit on stock wheels. What is the offset of your fronts? Going to a 335 rear without widening the fronts, will definitely promote understeer. Personally if I were to maximise grip, I'd stick to 20/21 and see if it was humanly possible to squeeze a 275/35R20 in there with 325/30R21 rears. The TTS does not need a ton more rear bite, it needs more front end grip if anything.

CanAutM3

Just going with the generic tires dimensions does tell much about how much rubber is actually on the road as tire construction can vary greatly between tire specs for the same nominal dimensions. TireRack provide a very useful tread width measurement in their spec tables to better compare tires between them. Further, running wider tires without using appropriately sized rims can actually be detrimental to handling.

I run the 991.2 GT3RS PSC2 N2 tires in 265/35R20 and 325/30R21 sizes and these tires offer significantly wider contact patches than the stock PZ4 NA1 I originally had on the car (a whopping 1.6" in the rear for only 1cm increase in nominal size). I specifically specced the Exclusive Design wheels because they are 0.5” wider in the rear and thus better suited for the N2 PSC2. Further, the stiffer carcass and grippier compound also noticeably improved the responsiveness of the chassis and overall handling dynamics, albeit with a little some in comfort and road noise.

Il CP

I get all of that. I run N1 spec GT3 Cup 2 shoes on my Pista for that reason.

I have the MPS4S K1 on my 812, and I know from personal experience that they are wide for a 275, hence why I mentioned that size. Not all are looking for Cup 2 shoes, and in the MPS4S range, the K1 275 offers more tread. Also, increased diameter also adds tread patch, it is not just the width.

I play around with tyre size a lot, and like to try different things. I'm well aware that the number stamped on the side is quite arbitrary, and only puts the tyre in a class of size if you will. Another great example of this is the K1 Cup 2 for the SF90. They actually run narrower than the N1 Cup 2 for the 991 GT3.

As for how rim width can affect handling, depends on a lot of things. Car setup and side wall stiffness play a big part. Some tyres are greatly affected, such as the Trofeo R, while the Cup 2 R generally does not seem to care much as long as you are within the specified rim width. I have tried the MPS4S 991 GT3 on a few 458's and 488's with rims ranging from 8.5" to 9.5" and there was little to no difference. Some tyres get a lot more darty and quick on a wider rim, the MPS4S has in my experience to been prone to that in a big way.

So again, if I were to mess with a TTS, my first order of business would be to find more front end grip. For this I would start by looking into either 275/35R20 or 285/30R20. The latter is actually very close to stock diameter, and it works well on a 9.5" wide wheel. The 599 GTO is a good example of this combination, so regardless of my previous post, that might well be where I would start. Will it fit? No idea, but I would definitely try to see if it was possible. 285/30R20 and 325/30R21 would be an interesting combo if it works.

If I were to play it safe for fun street use, I'd just go with the 265/35R20 MO1 and 315/30R21 MO1. MPS4S combo. Great balanced set for sure.

There are many ways to skin a cat.

Pad Bender

100%. I could not believe how much the PSC2 tires improved the handling dynamics. Cup 2s are meaty but work great with stock offsets of ED wheels.

If it was a pure vanity setup, 21/22 could look sweet with the right wheel, but I daily and prefer the taller sidewall of the 20/21 setup.

ER911S

I saw on another one of your post that you already have 15 track days. Congrats, you are my hero. I just did my first one and will probably never get to 15 but I am kinda addicted (will post about it tomorrow) but can you please advise what tires you recommend for the track? I am going to use my OEM Turbo S wheels for the track and getting a custom set for the streets (20/21) with probably PS4 in 325s in rear..

CanAutM3

In my case, I've been a long time track addict, hence why so many track days on my TT. I actually bought the TT as a multi-use car: it's my 4-season daily driver as well as my track toy. I love the concept of one car that does it all.

I had M3/4 for the previous 20-years, and with those cars I could easily shlep my track wheel-tire setup in the car. Not the case with the 992. So, I went for a hybrid setup, one that I can daily and track at the same time. Hence why I went with the PSC2. They are decent enough on track and can handle the daily duty just fine. I came to appreciate how fun it is to simply arrive and drive, without having to do anything to the car (save adjust pressures) before jumping on track. I am still working the fine tuning of alignment and pressure to optimize tire longevity on track, and so far I'm managing 7~8 days with the tires plus the daily use (my car already has 10k km on it), not too bad...

ER911S

Thanks for the quick reply. I DD my TTS as well and love the concept of one car being the jack of all trades. Since I am splurging on custom wheels, is there a better track tire that you would recommend over the PSC2? I thought I saw someone post Brigestone RE71 but maybe I am wrong as their website does not show our size available. I also noticed that there is a PSC2 for Mercedes that has stickier compound and is $100 cheaper?

CanAutM3

There's a lot of engineering work that goes in the development of manufacturer spec tires, I therefore prefer to stick with those. Hence why I went with the N2 spec PSC2 because they are designed for a 911 with the engine overhanging the rear axle. Further, as I posted previously, it is also more optimal to use rim width that are as close as possible to the spec rim the tire was developed for. The Dunlop Sport Maxx Race 2 in N1 spec could be another option.

As for stickier tires, there's always the PSC2-R or Goodyear F1-SSR options that are both available in 911 spec. Otherwise, you could always go with the Trofeo-R in generic spec. Here's a comparo review of these 3:

ER911S

Thanks for sharing your thoughts and the video. At $900 for the SC2R, it does not make sense for a non track guy like me. I will never enjoy the benefits of that tire.
The SCP2 at $600 seems to be the best bet as the Trofeo R is $750. The Dunlop is an option as well but with a tread wear of half the SCP2, for someone who drives his car to the track, the Michelin seems to be the winning ticket. No wonder why everyone is running it.
I apologize to the OP for derailing this thread.

Il CP

Try the Goodyear Eagle F1 Supersport R.
265/35R20 and 325/30R21. Very similar to Cup 2 R's but much cheaper. Have tried it on both the GT3RS and Merc GTR. Great shoe.