tungstenfoot

Hi all-

I bought my '03 Z in May and looking to upgrade my setup for dual purpose Street/AutoX next year. I have Bilstein sports and lowered slightly on stock bolts.

I want to maximize rubber width front & rear with NO rubbing w/ OEM 18" Speedlines, and keep speedo & Active handling happy w/tire diameter f/r difference: .5" to 1.5"max...Our tire choices are very limited...If I go 18" OEM Speedline's Front & rear, what is maximum front & rear width and ratio that works?

I like the BFG Goodrich Rival combo but not much increase in rubber (doesn't justify going to 10.5" width wheel in front either):
FRONT: 275/35/18 = 25.57" OD
REAR: 295/35/18 = 26.13" OD
Delta F/R = .56"

I want max streetable performance, not really concerned with wet performance. Any other suggestions? I'm hoping Rival's come out with more sizes this spring...i.e front: 295/35/18 and 315/35/18, would these widths rub with OEM speedlines?

Thanks for any feedback! Drive fast.

-Tfoot

Driver220

Ive seen people run 315s all around and be fine even with tcs. I just went to speedlines all around and will be doing pilot super sports in 285 35 18 in the spring.

directnosfogger

i'm on 315/35 in the rear and 295/35 in the front without any issues on my z. i just recently had a thread detailing this question. a bunch of guys posted up some awesome info about it.

Z06 rear wheels for front

tungstenfoot

Im real close to pulling the trigger on 4 295/35/18's but im a nervous nelly for 2 reasons: 1)excessive road following w such a wide front tire.
2)im not sure competition mode will still function properly...I could care less about traction control its hyperactive as is w stock setup.

Also im concerned about having to lower the front height too much to compensate for increase in front wheel height. I want 1/4-1/2" rake without hitting bumpstops ( plus i want rear slightly lower than stock)

mountainbiker2

If you want to run Rivals, I would go with 315/30/18 using rear Z06 wheels on all 4 corners. I run that setup, but with Hoosiers. Works great.

Steve

tungstenfoot

Cool, thanks for the link. You're on 18x 10.5" OEM front wheel? What brand front 295/35/18 did you go with and what camber are you running? sorry so many questions ...

tungstenfoot

hmm, what camber are you running with this setup? no rubbing? THe specs for Hoosier 315/30/18 and Rival 315/30/18 are real close, except for weight. My one worry is section width, since it doesn't include any tread block on sidewall, which the rival wraps treadblock over sidewall...so its really > 12.6", so rival is a wider tire in this size.

Tire------------Sect Width-----Tread Width---Weight----Overal dia
Rival 295/35/18---11.9------------11.1------------29#-------26.1
Rival 315/30/18---12.6------------12--------------30#-------25.5
A6 315/30/18------12.5-----------11.8-------------27#------25.6

mountainbiker2

My front camber is maxed out. Around 2.5 neg. The rear about 1 neg. I don't have any rubbing at all. Just go for it. Even if you had slight rubbing, it wouldn't hurt anything. Rubbing would not be my concern, but your paint might get more beat up. The tires stick out more. I'm not suggesting Hoosiers for DD. That's what I use when I go racing.

Steve

tungstenfoot

I gotcha, definitely not for DD. For me, tires are so expensive (and consumable) I just want to maximize performance per $ per year. I am considering maxing camber for autocross so no worries there, but I wouldn't mind keeping the square setup on for occasional street use too, with less aggressive camber (I dont want rub). So yeah, I'm looking for a true dual purpose setup (if I can), worst case I take off Square rival setup and use my staggered other set of stockers 17"/18" w/ DW conti's staggered.

For this reason I may just go with Rival 295/35/18 all around, this allows me max flexibility and performance for $...I can rotate the square Rival steup, hopefully no front rub with street alignment using 295/35. Then I can also can mix 17" DW conti front, with Rival rear, for when I want max traction (possible local 1/8 mile runs) this is nice because I know Competition mode functions as proper safety net for drags (maintains near stock overall diameter difference front to rear)

I just might pull the trigger on this unless some has experience with 315/30 rivals on front? anyone?
EDIT: 315/30/18 rear won't allow me the flexibility to run with dw 275/40/17 front AND keep proper OD difference, 315/30/18 is actually smaller OD than 275/40/17.

tungstenfoot

Whichever way I go, I'll report back here on the behavior of the active handling with square setup vs stock behavior. Maybe we can use this thread as a repository of informative posts on this..
As is, (completely stock tires right now, abeit admittedly old) the stock behavior is hyperactive to me (especially traction control).
Competition mode is decent stock, it has helped me a couple times I admit when horsing around. For AutoX, competition mode is slower than all OFF, I've proven it. its just too intrusive and hyperactive for me, it applies too much brake slowing momentum on Autox. I would like to better articulate to everyone here what (if any) active handling "issues" there are with running a totally square setup. It seems there is very little information other than just "you will have active handling issues". Others just turn everything off and report "no issues". That doesn't mean much to me...if you have a particular active handling experience or "issue" using a SQUARE SETUP that you can articulate, please post it up here- but lets keep this informative! please

For example:
1) Wheel & tire size:
2) Active handling setting: All systems active? or Competition Mode?
3) Conditions & what you experienced? Can you compare this situation to a stock setup, then please elaborate. (i.e. speed, conditions, what happened?)

directnosfogger

contenental extreme dw. couldn't tell you what camber as i didn't adjust the height (it's as low as it will go on stock bolts). you could easily run a 315 in the front as well.

tungstenfoot

The DW's are 12" section width on 10.5" wheel. Sweet!

ktlocklear

Here is mine on speedline 18x10.5's with 295/35 rear and 275/35 front Conti DW.






Track set up with 18x10.5 speedlines with 315/30 squared.....

tungstenfoot

^^nice thanks for the photographic evidence!! Can you run the 315/30 with mild camber and no rubbing in front?

ktlocklear

Define mild.....I've got -2.8 degrees on mine and they dont rub the fender at all

tungstenfoot

That is good reference point, but i would say -2.8 is aggressive camber. How much lower than stock height would you say ? Ever run those fronts at a more street friendly -1 degree of camber?

tungstenfoot

Also i'm assuming you have an alignment kit? I bought the hardbar alignment kit, which btw is the same kit sold by vansteel. My order from hardbar came in vansteel packaging.

ktlocklear

I ran the front 18.5's with the 275/35's with the stock alignment before I got the track alignment, and I had no rub issues....even the 315/30's. I'm lowered on aftermarket bolts currently as well. Only time I have rubbed the front fenders was on the track one time With the 315's and I wanted to try 5mm spacers.....so it must be close, because with no spacers, absolutely no rubbing. Also, I have no alignment kit......

oldvtr

Do you have extended brake cooling ducts installed for the front with this setup?

ktlocklear

yes...... LG spindle ducts and DRM brake duct kit