Reuster86

iTrader: (1)

'06 350Z Enthusiast prepping to run C-Street autocross. I've got Enkei RPF-1's on the car in the stock size 18x8 front and 18x8.5 rear.

I've basically decided on the Bridgestone RE-71R's, but trying to choose the best size.

Here's what I'm looking at:

245/40/18 front
255/40/18 rear

OR

255/40/18 front
265/45/18 rear

I'm kinda limited by the sizes available. See link:

https://www.tirerack.com/tires/tires...Potenza+RE-71R

I'll also do a few track days, and probably put 5k regular driving miles on it this year. Any thoughts? Anyone run similar sizes?

KRyn

Honestly I would run a square setup. With a Street Class Z you are not able to get any additional camber up front. You are going to destroy your front tires outside, side wall. Running a square setup will allow you to rotate inside, outside, front and rear.

I am running my 2007 Grand Touring in CS this year. I will be running a 285/30/18 RE71R front and rear on my 9" and 10" wheels. As such, I would suggest you run a 275/35/18 or 265/35/18 squared.

CK_32

iTrader: (1)

I had 255r/245f on my z when I got it in the stock wheels. Was actually pretty decent in the canyons.

I’ve moved onto 255 square off brands off my
old car I sold since I had them laying around for commuting. My track wheels are 275 square RE’s as welll. Haven’t seen a track event so I can’t really say how I like the square 275/10.5 set up yet.

Reuster86

iTrader: (1)

Thanks for the feedback. I assumed I was already pushing the limits considering a 255 on the front 8" wheel. Didn't realize 265 or 275 were even an option.

I've been running square. When I first got the car, I wanted to try a square setup so I split the difference between the recommended factory sizes, and put on some Hankook RS-3's 235/40/18 front and 235/45/18 rear. With that setup I could at least dismount and rotate the tires side to side, but I never got to the point they needed it.

I learned quick that 235's on the car were just too small. I thought not going to wide on the tires would stiffen the sidewalls, and I'd prefer it. Definitely not enough rubber, and grip is noticeably lacking at autox. Didn't much trouble with understeer, but the rear would come around quicker than I could catch it sometimes. I should mention I also have a reaally stiff front bar on the front from Stranoparts.

So this time, I'm aiming at more rubber on the front and rear, and possibly re-introducing a little bit of stagger, if only to compensate for my lack of driving skill.

CK_32

iTrader: (1)

My 275’s are on 10.5” wheels. My 255’s are on a 9”

KRyn

A guy in my club with a Civic Type R managed to have a 285/35/19 put on an 8.5" rim.

How many events (runs) did you do last year? I am guessing once I get around 100 runs on my new tires I will be looking to rotate them to maximize life and grip.

I can't stand understeer, it is the absolute worst. Since you plan to run the staggered setup perhaps dial in some toe out up front to help the car turn in a little better.

Reuster86

iTrader: (1)

I've had those tires on for 3 seasons. Maybe 12 autocross events at about 6 runs a piece, and 3 1hr track days. Of course, with age they probably got hard and wore slower.

Wow! 285 on a 8.5". I know I've seen 275/40/18 on the stock 8.5" rear of the 350Z, but of course can't get anywhere near that on the front 8". Good thinking on the alignment.

I'm close to pulling the trigger on one of these sets, but reading about TCS so long now I'm cross-eyed.

The 245/40 front and 255/40 rear I've seen from at least one other forum member, with pictures. So I know it works. That setup results in the rear being about 1.2% taller than the front.

The one I'd like to run is the 255/40 front and 265/45 rear. Making the rear 5.1% taller. (If the RE-71R was available in a 265/40 I'd do that for the rear, but not an option)

Factory is about 3% taller in the rear, and from what I've read, it sounds like + or - 3% from the factory will not create problems for TCS, but I'd hate to get them installed and find out otherwise. Also don't want it to look like an SUV in the back. Having a hard time visualizing it.

JMII

I run a 245/45-18 F and 265/45-18 rear to get around the 265/40-18 not being available with the RE-71R. VDC is happy with this setup. The tires are taller but I think they fill up the wheel wells better that way. Pictures here:
https://my350z.com/forum/wheels-and-...l#post10941589

plaight

iTrader: (1)

You could always go down to 17s and run the 255 40. You'll benefit from the lower gearing and should still be able to get to 61-62ish mph on the limiter. Lighter wheels too