ExMB

I believe that only a few will go with Hoosiers. Looking at Bob Woodman or The Tirerack sites I cannot find the 295/40-18 nor the equivalent front in 18" listed. I did find that rear size listing on the Hoosier direct site, but not the front.

There will be enough HPDE track rats that don't, that will look for other options and those are virtually non existing.


$0.02

ExMB

I'm confused by your rollout numbers. I use pi * dia which I equate to your rollout. That formula matches with your front, but not your rear.
I did the same with the Hoosier.

What am I missing on the OEM rear since I come up with 84.7" instead of 88"?

ExMB

OK, using that the Hoosier has a 1.02" bigger rollout/circumference than stock OEM

Now if only Nitto would get on the ball and make NT01s available in the proper -1 or -2 sizes

BGB Motorsports

No, you're right. I had the wrong sidewall profile on the rear the entire time. The rollouts are now equal and the math has obviously been reprogrammed in the ABS so i went and deleted all of that information i just posted.

Sorry if I wasted anyone's time or sent anyone off on a tangent but my simple mistake of 295/35/20 vs 295/30/20 led to essentially an hour of wasted effort. If they're the same size stock, matching the FR and R to be 84" will be way easier than finding rears that are 5% taller than the fronts.

Feel free to pick and choose your R7s from here and best of luck.

http://hoosiertire.com/rrtire.htm

Drjimh

The GT4 wheels and off sets are the following:
Fronts 8X20 offset 61
Rears 11X20 offset 50

The two problems here are the off set and the tire diameter. I am not sure other than maybe Hoosier that there is anything out there that will give you the correct diameters. I am not sure that cost savings are going to be all the significant to go to the trouble of changing tire and wheel size. Porsche seems to have locked those of us who track our cars and want a GT4 into a bit of a pickle for now. I think maybe in a year we have more options. I for one am planning on staying with 20 and getting a set of HRE RC103 made. Looks like about 5K for the wheels. That is about double what I paid for my track wheels for the R. Good luck. If anyone gets something to work please post. I am waiting until the car is delivered in Oct before I order wheels, but plan stands for now.

BGB Motorsports

Sorry...I think that I mistakenly painted a much worse picture than it really is. I had the wrong profile in the rear. Right now, from the factory you have an 84" front tire and an 84.7" rear tire. Therefore, all you have to do is keep that relationship constant which is much easier than it was when you needed to run a 5% taller rear tire than front.

NOW we are looking for a taller front tire because if you go with the 295/30/18 at 79.5" in the rear only the 245/40/18 at 79.8" matches; the 295/40/18 is 85.6" but the taller rear will not exacerbate the situation like being too short so you could get away with the taller 40 series rear profile tire. You guys might not like the look of the "short" 18" tires that are less than 80" and will definitely create some gap in the wheel well that you guys may not like.

Since this was beginning to even give me a headache i called Forgeline because now i am not in love with what's available for you folks on 18" rubber. If you want 18", you want a 9" FRONT and an 11" REAR and you want to run a 295 in the back and 235 - 265 up front. The only thing that comes close to matching that rear tire though is a 275/35/18 at 80.2" matched to a 295/30/18. 245/40/18 would match well to a 315/30/18 as they're both at or near 80".

For those of you that want 19s, Forgeline's offering is a 9" FR and an 11" REAR. The ultimate grippy setup would be a 265/35/19 at 82.3" and a 315/30/19 at 82.2". If you wanted to run slightly less rubber, you could try the 235/35/19 at 80.2" and in the rear the 295/30/19 at 82".

Sorry for the mistakes earlier and the long winded reply. Good luck! Let us know how we can help.

CMS

Thank you for all the feedback. Forgeline should have a set of GA1R 19" for our GT4 ready in a couple weeks. We are going to try the 265/35/19 R7 front and 315/30/19 R7 rear on our car. Both are within 1/2" of oem diameter. Once we are happy with fitment we will host a group buy with RL member pricing on a set of wheels, tires, and tpms.
CMS

usctrojanGT3

Nice, keep us posted.

Rovman

^^ Sweet, by all means, keep us posted.

Rovman

Thanks for the info, much appreciated. Yeah I am sure a few 19" tire/wheel package solutions will surface eventually. I am sure I will be content with the stock package at first but like always, will start to want to mod and tweak things here and there.

Mvez

This headache is just another reason mine won't be hitting the track anytime soon. Hell, I plan to downsize to 19" for the street. Michelin makes some PSS 245-40-19 and 295-35-19 sizes, which will look a lot better and ride even smoother.

I can't stand the ultra-low profile look, even for street cars. Drives me crazy.

Hopefully the aftermarket will mature quickly for these cars with options. For 19"
s, that is the size I would be asking people to make, it's identical to stock rolling diameters.

I'd still love to see a brake caliper that clears 18's, along with some 245-45-18 and 295-40-18 size NT01's....... I smell PMNA parts coming......

Mvez

The rear toe link seems to be very close for a 19x11" wheel with stock-ish offsets. I'm sure if you shim it enough for max camber (along with a cup/aftermarket toe link), it will give more clearance, but for those not wanting to run extreme camber, this may be an issue. My shop has already test fitted a rear 19" wheel.

Hopefully Forgeline is on top of this.

Hoosier already makes a 295-35-19, which is the exact same diameter of stock rear, so if they would just make a 245-40-19, it would be ideal for any 19" wheel combination, IMO. You keep handling balance, and more importantly, ride height the same.

ExMB

Details on that wheel please: brand, model, offset, etc?

zmon

interested! also know from my little bit of experience with the R7 on my E36 race car that they run very wide even compared to the R6...

Mvez

A 19x11" ET49 BBS CH-R was test fitted, which is basically identical to stock, and it hits the rear toe link, in stock camber trim.

So to make it fit, a combination of a spacer, and/or shims, will be needed, along with Cup toe links are needed to make a 19x11" wheel work with ~50ET/offset.

Forgeline is testing fitting some wheels at my shop tomorrow morning, and I'll be there.

I've said this again, after doing some math, it seems a no-nonsense fitment for any alignment, using stock toe links will be something like 19x10.5" ET44 (which gives 12mm more inner clearance, and identical outer clearance. A 295 tire fits ideally on a 10.5" wheel, no compromise made using this wheel size.

We will play with a 19x11" and see what it takes to make it work with stock toe links, if that is possible.

Instead of trying to stuff huge, low profile 265/315 tires under this car, I think the ideal will be:

245-40-19 on 8.5" - 9" front (offset TBD, but should be close to stock, 63)
295-35-19 on 10.5" rear (offset of about 50)

This keeps ride height the same, rolling diameter identical to stock. Start asking Hoosier and Tire rack for them to make the R7 in a 245-40-19 size now. They already stock the 295-35-19.