electron mike

Mine are 19" 265/35/19 F and 305/30/19 R on Forgeline wheels. I have camber plates and toes links with -3.0 F and -2.5 R camber to provide clearance.

jwr9152

Nice, I run 265/305 also. It really works well. I got the Dundon 1600 wing towards the end of the season last year and haven't really messed with AOA. Going to try some different settings this year and see how it does.

LZRD GRN

Please let us know how the wing works out....

Have been looking at it...

Cheers!!

jwr9152

I ran it at Road Atlanta and I was 2 seconds quicker. Lost 5 mph on the back straight, but I was running 10 degrees AOA. 7 would probably be more reasonable, but the car felt good and I was in the middle of a Time Trial so didn't want to change too much at the time.

LZRD GRN

Thanks for the info, WOW!!

Did you also add the Dundon dive planes??

Cheers!

jwr9152

Yes and I have the GT4RS underbody aero. Well all except the very center front pieces which I just added yesterday.

enduro

Guess I'll pick up the dive planes next time Dundon has a sale. I need to attach my splitter and crank my AOA a little and see what it does for the GT4 on my track. (have DBJ 1600mm swan neck)

lovetoturn

The 265/305 set up on 19 inch wheels is the way go. More grip overall and shifted more to the front where it is needed. Then you don't need to be making major sway bar changes to fix the inherent under steer characteristics of the car. A softer front sway bar softens up the front and makes it less precise, while a harder rear bar makes the car less compliant off the corners. So being more in the M/M range on the bars is a better place to be. On 19 inch tires and wheels, you are also 9mm lower to the ground, which also improves downforce in both the front and rear of the car.

With more relative front grip from the 20mm wider tires, only 10mm in the rear, you can add more rear downforce with a wing and not be as susceptible to aero induced understeer. Of course adding the 4RS front aero guides with any major wing upgrade is a safe and logical upgrade.

Question: Aren't the DBJ and Dundon parts the same or nearly so?

jwr9152

Yeah, don't know if you remember but you measured it for me, because I was going to get that one also, but they were sold out for ever so I went with the Dundon bolt on. Did you get the DBJ splitter? I've been looking at that also

enduro

Yep, remember measuring it. Bummer he sold out, I like the fit and finish of the piece. And yep, bought the splitter at the same time, but haven't gotten around to fitting it. Just run the wing at a fairly low AOA; makes more downforce than OEM, but haven't cranked it up yet.
Wing looks very similar in cross section, but my DBJ is on swan neck mounts. Just got my 265 35, 305 30 19 RT660 fitted. They look quite a bit bigger than the same nominal size Cup2 I currently have on the rear.

If the built Miata engine doesn't show up soon, I'll be running them on the GT4 @ ECR in March. Will prob see you there.

lovetoturn

Interesting.

Looking forward to it.

alwaysdriving

Lovetoturn,
why didn't you go for the 18 inch? i'm wondering since we are replacing the brakes we could go 18s which will be perfect same as the clubsport GT4s. please correct me as i'm tempted to go either 18s or if not 19s for a track setup

jdmporscheguy

Do you know if this wing will fit RSNV risers? If so, Jacob is about to get a new order.....although says it's sold out on website atm

jwr9152

Verus makes the two for Dundon and they do have a swan neck like DBJ, but I have the direct bolt on one.

lovetoturn

An 18 inch wheel will not fit over the OEM brakes. If you spent like about $13K on the PFC brake kit, then you could fit an 18 inch wheel like on the Clubsport. The 265/305-19 set up is the best IMHO.

1. The tires are wider and the stagger changes reduce understeer by providing more front grip.
2. Your ride height goes down some but not crazy low like the Clubsports.
3. Your gearing is shortened by about 2.5 percent, which is great for acceleration on a car that is said to have gearing that is too tall.
4. Plenty of available tires to chose from...when they are in stock.
5. The ride height on both the front and rear tires is identical keeping PSM happy.
6. Car still looks good. The 20s look the best, the 19s are ok, and the 18s are a little too small for my tastes.
7. They fit over the stock brake calipers without any modifications or spacers needed.
8. They fit the wheel wells with minimal modifications, which mods are things that we all will do anyways to prep our cars for the track to have a good -3.0 of camber up front. I am up to -3.2 now.