Anyone read the project 350Z article in the new issue of Sport Compact Car? They recommended using the same size tires front and rear (i think it was 265's). They got 1g on the skid pad in both directions with out coilovers and without lowering, just using sways and same size tires front and rear. Any opinions?

 

It was a terrific article, one that all of us should read. I completely agree with the magazine that the stock suspension has nicely tuned shocks/springs, and just needs more rubber (equally wide front & rear) and adjustable swaybars to achieve big grip and neutral balance. They also played around with the diff, but I don't think that they regard this mod as essential for achieving 1g.

 

yeah they ended up getting the best handling after setting the kazz diff pretty soft and the hotchkis sways were set in the middle front and rear. They made some good points about hollow verses solid sway bars as well.

 

i have been running the same sive front and rear on my track ed. & it's amazing what it did for the car! it was a more dramatic change than going to cusco sways & s-tune shocks. the car is perfectly balanced now. i am running BFG-KD 245-40-18 btw.

 

Doesn't this mess up your TC/VDC? Or did you modify VDC so that it wouldn't freak out? If so, how?

Thanks.

 

Matt, are you using these on OEM track wheels? Which I think are 8" & 8 1/2".

This would mean (I think) softer front sidewalls than the rear. I'm confused as to if this is the BEST solution for my track use. Or, did you put your wider rear wheels on the front?


I WANT NEUTRALITY!!!!!

 

The ratio of widths between the front and rear wheels are 9" and 9.5" in the magazine, similar to the 8" and 8.5" ratio with the track wheels. So about the front softwall, I guess the Z in SCC has that characteristic as well.

About VDC, the one in the magazine is not equipped with this option so the required stagger in the rear is not required. Thus, all 4 tire sizes could be kept the same. However, there is a stagger that is maintained by the offsets. The rears are 25 and front is 30mm (42mm with 12mm spacer). This gives the rear a wider stance for better handling/stability.

 

Yes, but Matt G. has the track model WITH VDC. So how did he circumvent this issue?

 

IMO, running equal sized front and rear tires doesn't effect the VDC. I've run all winter with same sized front and rear tires, and trust me, I lived in VDC a lot. I believe that issues arrive when the front is taller than the rear though.

As for the Track rims, I've considered the same scenario (if I purchased a set), and IMO I'd go with the slightly wider rim up front for better turn-in precision. There's also less camber up front, so a more square sidewall (from a wider rim) will help prevent the tire rolling so easily under load. There was an old SCC article I rememebr reading where they drove a JDM EVO. The tuner had put a 9.5" front vs 8.5" rear (same sized rubber front and rear) to reduce understeer and increase steering precision.

As for the SCC article, it appears as though they only ran a 9" front b/c BBS couldn't supply them with a 9.5" with the proper offset.

 

Interesting. But doesn't this throw off your speedometer reading?

 

Only if you change the overall tire height will the speedo be affected.

 

VERY INTERESTING!

How does this set-up sound: 17" x 9" all around, with 255/40 F & 255/45 R? Or to make rotation easier, just use 255/40's all around.

 

you guys should watch some of the best motoring videos, some of the japanese tuners have been doing this for awhile (all 4 wheels the same size for track). The amuse setup seemed to work really well, i think it was 265 all around on 18" tires.

 

But aren't you doing this with the front by making all four tires the same height, thereby eliminating the stagger height difference?

 

This setup, 255/45 in the rear, is certain to play games with the vdc because now your tire height in the rear is less than the front.


All the tire sizes proposed here are very close to the stock tire height and will not have much of an effect on the speedo.

 

[QUOTE]Originally posted by jckolnturn
[B]This setup, 255/45 in the rear, is certain to play games with the vdc because now your tire height in the rear is less than the front.

Tim, #1, read my sig, I don't have VDC. TCS, but no VDC. #2, a 45 series tire is TALLER than a 40 series.

I'm still waiting for some black 9 1/2" lightweight 17's for my perceived hot set-up.

 

oopsy i mixed some of you guys up, somebody asked about VDC and i wasn't looking at your sig. Your tires would work fine, just disregard me LOL About your rims SCC magazine had a problem getting their BBS fronts in the right offset, they needed to use a spacer. I hope you can find some. But they said BBS would be making the correct offset in the near future.

 

Speedometer is read from the rears.. so the front being a different height wont matter anyway. You do want to maintain the same size diameter though when you swap out tires.

 

yes it dose make VDC react alot quicker with the same size tire all around but i turn it off everytime i get in the car! and my speedometer is off when it says im going around 140 its really about 132+/-. but this dose make the car perfectly neutral its better than my 3rd gen r-x7's which is saying alot. ABS dose come in quicker also but if you mainly drive on the track (like i do) its worth it because ABS dosent even come in to play when your going 130mph+ and nail the brakes only when you going aqround 20mph or less can you tell ABS is engaging quicker. hope this helps!

 

If you are keeping stock 18" rims, I would recommend 245/40-18 front, and 245/45-18 rear. You will keep the factory stagger, as the 245/40 is identical to the 225/45 and still have the same width all around.