have decided these are the wheels I will be going with. My biggest reason is that I had a 1000 dollar gift from PCA for a rookie award from a bit back and I wanted to use it towards the wheels. Using this I would be at 2314 for the whole set which is half the price of the BBS wheels ! Forgeline asked me what offset to use so I wanted to ask you experts about that before I ordered the wheels. Also should I do the silver or gunmetal center on a black car, or maybe even a polished wheel? Thanks to all of you for your help. I am sorry for all the newbie questions. I just want to end up doing this right

 

That's a nice choice for a wheel man, i would def. go with a Gunmetal center, as for offset's i dont know which would be best for track use and the most aggressive! Goodluck man

 

boyracer...I saw you on that 'other' forum...backspacing depends on the width of the wheel...forgeline measures it as front spacing (the distance from the outside of the rim to the back of the wheel center that fits against the rotor) and back spacing (the distance from the inside of the rim to the back of the wheel center that fits against the rotor) see the attached pdf from forgeline and you will see those are dimensions 1 and 2 on the drawing...if you are using stock GT3 wheel sizes 18x8.5 front and 18x11 rear then the offsets are 40mm front and 63mm rear...that would mean for the front wheels, dimension 1 is 40 mm less than dimension 2 with 1+2 being equal to 8.5 inches...for the rear wheels, dimension 1 is 63mm less than dimension 2 with 1+2 being equal to 11 inches...btw 40mm is 1.5748 inches...63mm is 2.48031 inches...for the front stock wheels 1 is equal to 2.6752" and 2 is equal to 5.8248". for the stock rear wheels 1 is equal to 3.01969" and 2 is equal to 7.98031". To have the wheels fit perfect you need to check all of those measurements requested on the form...you probably can get some help from their tech department as they have most likely made wheels for a GT3 before...tell them if you have steel or pccb brakes...nice choice...should look great...choose center color to suit yourself...
http://www.forgeline.com/wheels/fitment.pdf

 

What VSE said.

 

Here's what I got from Forgeline when I asked about the SX3-Rs that I have on my car (and the tire info for what I have on the car now):

Wheel Information
Size: 18 inches
Front Wheel Width: 9 inches
Rear Wheel Width: 11 inches
Wheel Finish: Gunmetal
Bolt pattern: 5 X 130 / 5 X 5.12
Front Wheel Offset: +49
Rear Wheel Offset: +64

Tire Information
Hoosier Grand Am Cup
Front Tire Dimension: 245 / 40 / 18
Rear Tire Dimension: 305 / 30 / 18

 

The offset you size and offset you want is as follows:

18x9 +50 & 18x11 +63 the difference of a couple of mm either way is no problem as there is alot of room under the front and rear fenders, The rear fenders are rolled by the factory so there will be no rubbing issues.

As for the tires: Michelin is best for driving to the event using the car and driving home. They run a little bigger than the other brands especially if you want to run 315 rears, the better fit is the 295 with no issues.

The Hoosiers are very sticky and great if you trailer the car to the track use it and put it back on the trailer.

Yokohama is a nice tire as well but I understand they are in high demand and short supply check with your local dealer.

Pirelli runs alot smaller in the 315 so if you want to try this size it is a safe bet they will work without rubbing.

Good Luck and have fun that is what is most important.

 

Tire size: 235/40/18 front
295/30/18 rear or 315/30/18

 

Rennworx, why would you want to go up to a 9" wheel in front and then still run a 235mm tire?

 

Because it is the only tire size offered by Michelin,Pirelli,Yokohama that will work. The next size in Michelin is 265/35/18 and Pirelli 255/35/18 niether size is ideal. As well the bigger sizes are heaiver any weight savings in the wheel and tire significantly reduce the momment of inertia this saves a considerable amount of power in turning the wheel thus allows for lighter,sharper steering.

 

In addition the section width on a 235/40/18 is 9.5 and the section width on a 245/40/18 is 9.6 not much gain for that much more weight as well they do not offer this size only Hoosier.

 

I understand...but the stock wheel is 8.5 with 40mm offset and 235 tire...going to a 9" wheel isn't necessary to run a 235 tire unless they fit better...are there any bumpsteer issues with the larger wheel and additional offset running the same size tire? Not flaming...just curious...

 

It spreads the tire better on the 9 and the offset is adjusted to +50mm to compensate. If you check most of the GT3 RS guys in Europe run this combination as well in the POC for the GT3.

No problem with bumpsteer.

I am just passing along what I run and have had success with it is just a suggestion and 8.5 will work as well but the tire guides will show a 235 to fit on a rim range of 8.0-9.5 and the section width is based on a 8.5 rim so naturally you get more section width out of a 9.0 width rim.

 

thanks...appreciate the info

 

thanks for the info guys. I am going to be running these on the street and my stockers on the track. I am going to be using MSPCs for DEs and Hoosiers for races. So I will be putting the stock PS2s on the Forgelines. Should I still go 18x9 and 18x11? If I do go 18x8.5 what should the offset in front be? Thanks again for all of your help?

 

Of course the differences can be quite easily calculated by yourself but here's a calculator for that, http://marksink.com/tire_wheel_offset/offset.htm

With the above link it's easy to compare to your stock wheels and it helps deciding what you want...I suggest a bit more agressive setup