Originally Posted by mooty

^ very helpful

i have ran mpsc2 255/35/19 & 295/30/19

i think 265/285 may be a bit too frisky in the rear (i am just guessing here). will 265/295 work. i think if that works in terms of diameter relative to OE, this could be THE size.

Originally Posted by Mvez

Here's the deal guys, 18's can fit, but they require specific offsets and widths.

For example, Finspeed's F14 wheel will fit. He has already confirmed the 18" front wheel clears the 991 GT3 brakes, so they will clear ours.

The rear will fit easily, but requires a 18x10.5" wheel, ET44, if you want to avoid using alot of rear camber to clear the toe-link. The problem is tire sizes, there are currently not any 18" tires with more ideal sizes, which need to be:

245-45-18 and 295-40-18 (or 285-40-18).....these will keep rolling diameters the similar and keep your TC/PSM happy if you keep it on.

I would start asking Nitto and/or Hoosier to make these sizes. It will likely take a year or so, but would be well worth the effort.

For anybody who thinks its too tall of a tire, or the "sidewall is too big"...that's total hogwash. I run 245-40-18 and 275-40-18's on my 987, and they are perfect. I never get any "ice mode" or ABS problems, compared to the fairly regular complaints of those running the 275-35-18 rear. Those sizes provide a much better load rating as well.

285/295-40-18 on the GT4 would be great.

Originally Posted by orthojoe

Is anyone planning on going this 18" route? If you'd wanted nt01 with this setup, it would be 245-40-18 and 305-35-18

I test fitted my old te37 off my spyder on a gt4 last week, and the wheel would mount to the hub, but the barrel as waaay too close to the caliper

Originally Posted by mooty

i want to thank ExMB, TAG and Mvez. we now have some real informative data on wheel fitment. i am waiting new season to try stuff out....

Originally Posted by ShakeNBake

I've got a nice little xmas present on the way from Forgeline, with a 265/295 R7 setup mounted.

Originally Posted by STALKER99

Specs? Which wheel did you go with?

Originally Posted by paradocs98

Just an update and reminder--BGB has arranged a Forgeline rennlist group buy with significant discounts on the GA3R (3-piece) and GA1R (monoblock). I'm going with the GA3R in 19x9 and 19x11. This will be my third set of Forgelines--great wheels. I asked about the possibility of a 19x9.5 up front to better accommodate 265 front tires, but John at BGB and Steve at Forgeline had significant concerns about fitment with that wide of a front wheel. I don't want to put 265 section tires on a 9" wide wheel, because that wheel width is the narrowest recommended for that tire size. Seems like it would be sidewall rollover city up front doing that. There's a reason why race teams put the widest wheel possible on any given tire width...
And John at BGB thinks the 305 Michelin SC2 will be too fat in the rear, so looks like I'll do just as mooty suggests above: 255/35-19 and 295/30-19. Both sizes available in Michelin SC2 and Yokohama AD08R. They have same outer diameter measurement, so no significant change in rake of car. The wider front will hopefully dial out some understeer. And the 1" reduction in outer diameter will be like running a shorter gear set on track...

Originally Posted by usctrojanGT3

I can confirm that there's no issues at all with running a 305/30/19 Dunlop Race Maxx on a 19x11 wheel with a 5mm spacer.

Originally Posted by TAGMotorsports

HRE does make a 19" fitment that works on the GT3 and GT4 without a problem.

There is not a bolt to flip on the GT4. It's not the same issue as the GT3. You can run the 19 it just has to be either very aggressive for an 11 or down size to a 10.5" wide wheel.

The next question is tire size & availability:

Now with the 19's, We you can basically go with a 9" or 9.5" FRONT wheel and run a 265/35/19 - the tire's OD will go down about .5" but the good news is that you have options on tires - The Pirelli Trofeo R, Michelin Cup2's etc.... They are all available in the 265/35/19. Moving to the rear, you run the 295/30/19 which is basically .9" shorter in the rear that factory. The other option is to run the 285/35/19 which is available in the Trofeo R or the Cup2. That size will put you at about .1" shorter OD as factory 20".

To recap - Factory sizes:
20x8.5 - 245/35/20
20x11 - 295/30/20

If you want to go with a 19" Setup - Your options are the following (based off our research form us and our neighbors across the street at HRE Wheels)
19x9 or 19x9.5 - 265/35/19 (.5" shorter OD from factory) (Trofeo R & Cup2 Tires available)
19x10.5 - 285/35/19 (.1" shorter OD from factory) (Trofeo R & Cup2 Tires available)

Now moving on to those who are looking to stick with a 20" option just want something else other than the Michelin, - currently we are working with Pirelli on getting the 295/30/20 Trofeo R's here from Europe - HOWEVER we do not have an ETA. I would say 4-8 weeks at least. (PM ME to get on the wait list for that). We are owned by a large chain of retail tire stores in Southern California so we are trying to muscle our way into getting what you guys need haha

In the meantime - if anyone has any questions at all - feel free to contact me. We can custom make you a set of HRE RC1 series for track use for those who are wanting to go down to 19's without a problem and with the sizes shown there - you might be able to dial back some of the understeer issues as well.

Hope this helps!

Originally Posted by James-GMG

Going to keep it basic for our GT4:
BBS CH-R
19x8.5" ET51
19x11" ET56 plus 12mm spacer
Hoosier R7 in 235/35-19, and 295/35-19

I plan to track this setup with our headers and exhaust with our harness bar.


Attachment 997575

Attachment 997576

Originally Posted by usctrojanGT3

I can confirm that there's no issues at all with running a 305/30/19 Dunlop Race Maxx on a 19x11 wheel with a 5mm spacer.

Originally Posted by Yargk

What was the offset on the 19X11? Do you think 19x11.5 would work (or 19x12)? (obviously with 305s still)

Originally Posted by Yargk

With a 265/35-19 tire, will 19X10s fit on the front?