Choose my wheel + tire setup...because I cannot.
 

The Z is a weekend car and sees the race track 3-4 times/year.

I have a track weekend in 2 weeks and am stuck deciding on what wheels and tires to use.

I've reached the point of analysis paralysis from searching the forum and am confusing myself at this point...would love your input.

I've previously run the stock Rays on PS4S and the car does understeer and when the tires get too hot, they get slippery fast. They started to chunk on my last weekend, so those tires are shot.

I really wanted to run a square-ish setup with Hankook Ventus RS4s (or another 200TW tire), but that seems tricky.

Wheel Set 1 - Stock Rays

Wheel Set 2 - Forgestar F14s w/ new PS4S

Front: 19x9.5 20mm offset, with 255/35/19
Rear: 19x11 15mm offset with 305/30/19

Car is lowered on Eibach Pros: 0.9" front / 0.8" rear. The rest of suspension is stock, except for Whiteline front sway.

Here's what I *THINK* my options are:

1) Run the Forgestars, as is. Expect more understeer since the tires that are on it are 255f/305r. (But maybe more grip overall since the tires are new vs. the old worn ones I was using?)

2) Run the Forgestars, but swap the 255 fronts for 275/35s PS4S. This should, in theory, reduce understeer and be more neutral. I think 275s is the max width tire for a 9.5in wheel.

3) Take off the PS4S, put them on the Rays (if they fit). Get 200TW set for the Forgestars, but TireRack/Discount only has 275/35s in stock for the RS4s. No 305s. So I need another 200TW option.

4) Run the Stock Rays, and run 275/35s RS4's all around. (But I couldn't find a definitive answer if 275s fit on the front Rays, and if I'd need to also get a spacer).


I think option #2 probably makes the most sense, I just know even Michelin says the PS4S isn't a track tire and since I have two sets of wheels, I might as well see if I can make a decent track setup out of one, and keep a good set of PS4S's for the street.

Definitely overthinking this now....what do you guys think?

Choose my wheel + tire setup...because I cannot.
 

I propose option #5: find 2 more rear stock rays for a square set and run 275 square RS4s. Shouldn’t be too hard to find someone selling stock rays and this would be cheaper than buying another square set of track wheels.

Otherwise I’d say option #4. Changing to 275 square RS4 will be a more noticeable increase in grip, compared to upping the width on the forgestars. Usually compound > width. And For reference, I run 285/35 PS4S on 9.5in wide front wheels and honestly they fit perfect. They could be wider and still fit, but the RS4s might be a different story. You’d probably want a 15mm front spacer if you go with this option since the stock front rays have a conservative offset

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So -- to clarify, for option #4, this will work?:
- Stock Rays
- 275s all around will fit
- 15mm spacer up front for clearance

Ah -- but just realized if I put on a 15mm spacer, I'd need to put on extended studs too. Then I'd need to remove the spacer and studs to put the Forgestars back on. 5mm doesn't need extended studs though...

Choose my wheel + tire setup...because I cannot.
 

Yes it will work. The front tires might have a slight “bulge” to them but it won’t be a problem.

You probably don’t even NEED a spacer, so I’m sure 5mm is sufficient. Or instead… get larger spacers, use extended studs and get open ended lug nuts, but that’s more work. I’d stick with 5mm spacer and avoid the headache.


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Appreciate the info. I just pulled the trigger on this, will get them mounted up next week and see how it feels. thank you!

I am running 275/35R19 RE71-RS square on the stock staggered Rays with no clearance problems and no spacers.

Huge difference running 275s all around last weekend at Eagles Canyon Raceway.

The car was much more neutral with a tad bit of oversteer, but predictable. Enough that I felt comfortable turning off TC and VSC and still punishing it 9/10ths.

And the Hankook RS4s were a night and day difference over running PS4s and could take a lot more heat before they started feeling slippery.


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