Mvez

We need a correct 19" downsize from 20", which is 245-40-19 and 305-35-19. It provides perfect rolling diameters, better ground clearance for street driving, more alignment/rake tuning options, and ideal handling/stock balance. NT01's run big anyway, so you don't need to stuff massive tire size to make this car work, it works fine with stock widths, but we need more appropriate rolling diameters so we can drive on the street without crazy low ride heights, or ugly wheel well gap to avoid overly low ride heights. This also allows for use of 9" and 12" wheels without extreme offsets or camber needed.

Sure, there are some 265-35-19 and 325-30-19 tires available, but they still drop the car pretty low, and I'd rather have better ride height than 20mm more tire width. I'll say this again, this car really needs a 35 rear aspect ratio tire, especially if you like your diffuser.

So we did this back in the day for the 997 GT3/RS, and Nitto obliged (within about 1 season), but only because lots of Rennlisters got on their website and requested the size. Back then we need an 18" downsize from the stock 19", which was 245-40-18 and 305-35-18, and provided the same benefits. Today, it is THE go to size for any 997 track car. Let's make this happen for the 991 GT3.

Click on this link and request the 245-40-19 and 305-35-19 if you want some NT01's for the 991 GT3. Nitto listens.

https://www.nittotire.com/find-a-tir...t-a-tire-size/

ExMB

Wasn't that done for the .1 as well?

Jnosol

If you're going to request a custom size, why not 255/40/19 front and 315/35/19 rear? It's only 8mm larger OD front and 6mm larger OD rear. Wider treads and best of both worlds.

You're correct on 265/35/19 and 325/30/19 rear. The OD alone lowers the car by 10mm and requires lowering 10mm + camber to clear. So that puts the car heigh 20mm lower than stock. I just now thought of this, might change my mind on ordering 19" wheels now.

Mvez

I agree, but from both a manufacturer's recommended size (think legalities, similar to why Tire Rack always asks what car you are buying tires for), and business case justification standpoint for Nitto, it always seems easier to start with the same size that comes on the stock car. This means when Nitto looks at this, they can see that this size will better fit ALL 991 applications, including GT3, instead of a super-narrow fitment for just a single car, like an RS fitment. Start with the size that is most likely to get made, then go for additional ones. The 245/305 size would work much easier for virtually every 991, narrow and widebody fitments.

As soon as the 305-35-18 got offered, a big portion of all 997 owners moved away from the 315-30-18. You don't typically see aftermarket offering tire sizes with larger rolling diameters than stock for a "minus one" size, even if it is very close.

Wind911

mdrums

Mr. Turtles

I know some guys who ran these sizes all last season (Hoosier R7) with no issues. Depending on rims you may need to adjust camber/caster but nothing ridiculous and easily handled by a decent alignment shop. From what I heard the 265's up front provide lots of grip and with the 325's in back the car is well balanced and sticks like crazy.

Tay101

I like where you are going with this Mvez. I think those sizes would be perfect.

That being said, I think we should request for the new Toyo R888R in those sizes. Its basically an updated version of the NT01. It is nothing like the original R888 which were horrible. I have upgraded from the NT01 to the new R888R on my GTR and I do feel that it is much better than the NT01 and the NT01 is a great tire.

By the way, the R888R does come in a 20" size that would work with the stock wheels, 255/35/20 and 315/30/20.

https://www.toyotires.com/tire/patte...petition-tires

Mvez

Done, just sent a formal request for 19". I agree, we should request the same size from both vendors, maybe it will speed up the whole process.

There are a lot of guys who want to drive to the track on the same 19" tires they use on the street.....like a SC2, Trofeo-R, Nittos, etc......if you want Hoosiers, Cup2, or Trofeos, you already have those 265/325 sizes available. What isn't available are correct diameter/size 19" tires for people who don't want to lower their cars, constant alignments, or swap track wheels and street wheels. I have 2 other track cars that I tow to race track, I can run slammed ride heights or extreme tire sizes for ultimate grip. I want the GT3 for driving to the track, then driving home, but on 19" wheels and tires. I hate how 20" wheels look, and I am not alone on this. Michelin and Pirelli are too big to listen and make it happen fast, Nitto listens and can make things happen faster. There is a reason they have a link specifically to request a tire size.

orthojoe

Even though 305 is OEM width and NT01 run wide, they might not be wide enough still. If you look at the rim width recommendation for the 305 NT01s it is ideal for a 11" wheel and not wider than 11.5" Our OEM rear wheels are 12"
In my .1 I ran 19" RE71R that came in 305 on 19x12 wheels, but the tires looked stretched and the inner/outer edges would wear prematurely as a result.
I came to realize/learn that N spec 305 tires are special because they run an entire inch WIDER than non Nspec tires per the tire rack website.
I would want to run 325 NT01 tires on 12" wheels.

Tay101

I agree orthojoe.

What if we request a 255/40/19 and 315/35/19 or even a 265/35/19 and 325/35/19?

Wind911

It's Interesting to know that N-spec 305 tires run wider, how about the N-spec fronts?
The NT01 is available in 325/30-19 but no suitable front tire choice. A 265/35-19 would be nice.

orthojoe

Hmmm... I'm looking at the tire rack website right now and a few things I notice:

1) the 245 N0 is 9.6" tread with, but the N1 spec is 8.8" and the standard spec is 8.9" tread width and K1 (ferrari) shows 7.6"
2) the 305 N0 tread with is no longer listed and the new N1 spec is listed as 11.6", the K1 (ferrari) at 11.7", and R01 (audi) 11.2"

I wonder if tire rack's data is wrong or their measuring methods are incorrect/inconsistent. There is no way that the k1 ferrari 245s have 2" less tread width than N0 spec

I assumed they were right based on my RE71R 305s looking stretched on 12" rims and wearing quickly on the outer and inner edges, but maybe not?

ExMB

Tirerack tread width

Interestingly those tires carry the same section width but based on tread width some seem to have a more rounded shoulder

maspirito