running 4 same-sized wheels+tires on the track?
07-02-2007, 05:22 PM
#21
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Originally Posted by scotts300
2nd. I run 17x9.5 with 275/40/17s as well. Yum.
Thank you.
07-04-2007, 10:32 PM
#24
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Proper fitment aside (which I'll address when I get the full specs on the wheels we run in Auto-x, which I can't recall right now) let's think about this problem. The Z is a car that, while it rotates extremely well under constant radius turning using throttle steer, suffers very badly from understeer in a road race/auto-x setting. So why go with a staggered set-up where you have bigger tires in the rear? Exept in a drag race setting where traction in the rear is paramount, this makes no sense.
To solve understeer the most direct solution is the even out the contact patches in the front and rear, so the car is more prone towards oversteer. So, the answer is YES, you can fit the same sizes front and rear (we run 245's front and rear for auto-x in the stock class without spacers or aftermarket rims) and YES, this will make the Z handle better in this setting, and probably on the street as well.
To solve understeer the most direct solution is the even out the contact patches in the front and rear, so the car is more prone towards oversteer. So, the answer is YES, you can fit the same sizes front and rear (we run 245's front and rear for auto-x in the stock class without spacers or aftermarket rims) and YES, this will make the Z handle better in this setting, and probably on the street as well.
07-05-2007, 02:21 PM
#25
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Here is a question then what is the necessary offset that you need to get in order for you to be able to rotate back to front and so fourth? Right now I have 235F and 285R so you can image the kind of understeer that I have (this is my crusin rims and they are 19's). I am in dire need of an auto-x setup and need to figure out what kind of offsets are needed to be able to run 275 tires all around.
Thanks all
Thanks all
07-05-2007, 02:31 PM
#26
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On my 17x9 fn01rc's they are +35 and I use a 3mm spacer up front to clear the stoptechs and the upright arm, so effectively +32.
On my 17x9.5 ProRacer GN+'s I use +38's with the same 3mm spacer so effectively +35.
These are not ideal offsets on the 350z as the wheels are tucked in a bit too far but they do work - they clear the suspension fine and they clear the fenders fine. These wheels fit my Z32 also though so that's why I run this particular setup. I think a more ideal setup would be +20 to +25.
I'm sure more guys can chime in though with their exact offsets.
On my 17x9.5 ProRacer GN+'s I use +38's with the same 3mm spacer so effectively +35.
These are not ideal offsets on the 350z as the wheels are tucked in a bit too far but they do work - they clear the suspension fine and they clear the fenders fine. These wheels fit my Z32 also though so that's why I run this particular setup. I think a more ideal setup would be +20 to +25.
I'm sure more guys can chime in though with their exact offsets.
07-09-2007, 01:55 AM
#30
I can confirm now that it works - I have my 4x LMGT4 18x9.5s with Bridgestone Potenza RE050a Pole Positions on the car / put about 20 street miles on it. SLIGHT rub on parking-lot-speed near-full-lock turns but I think it's the intake hose for my turbo kit (which is coming off in a few weeks anyway).
07-09-2007, 04:40 AM
#31
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I'm running 275/40/17 on stock 17x8 autocross rims on all four corners (5mm spacers in front & 25mm in rear). I had to roll the rear fenders due to the 25mm spacers. My Z is also lowered over 1" but no rubbing issues. Here is a pic of my 17" autocross setup from yesterday's autocross:
07-12-2007, 02:58 AM
#33
So far I love the way it drives.
Unfortunately, I'm lacking fender-liners right now (long story) and managed to snag/tear an aftermarket wire for my HID high-beams, grrrrr.... I knew I should have routed / zip-tied / secured that better. Wasn't really an issue with 245s lol. I had to pull the power to the relays for my high-beams until I can get a chance to replace it, it's a high-voltage line from the ballast to the bulb and that would be downright scary to energize while just "hanging out" down there.
On the flip side, no rubbing / no issues with clearance on the a-arms, wheel wells, fenders, etc.
I've got some suspension goodies on their way shortly so we'll see how it does a bit lower / with more camber
Unfortunately, I'm lacking fender-liners right now (long story) and managed to snag/tear an aftermarket wire for my HID high-beams, grrrrr.... I knew I should have routed / zip-tied / secured that better. Wasn't really an issue with 245s lol. I had to pull the power to the relays for my high-beams until I can get a chance to replace it, it's a high-voltage line from the ballast to the bulb and that would be downright scary to energize while just "hanging out" down there.
On the flip side, no rubbing / no issues with clearance on the a-arms, wheel wells, fenders, etc.
I've got some suspension goodies on their way shortly so we'll see how it does a bit lower / with more camber
07-12-2007, 06:26 PM
#34
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Ive been running 275/35 all around too. Handles alright atm now. Still need adjust alot of other setting.
also, i dont wider is always better unless you have the power to back it up. I suggest not running anything wider then 275 if u are NA since you lose alot of speed in acceleration in such with wider tires.
also, i dont wider is always better unless you have the power to back it up. I suggest not running anything wider then 275 if u are NA since you lose alot of speed in acceleration in such with wider tires.
07-13-2007, 07:41 AM
#35
also, i dont wider is always better unless you have the power to back it up. I suggest not running anything wider then 275 if u are NA since you lose alot of speed in acceleration in such with wider tires.
07-13-2007, 09:30 AM
#36
Originally Posted by mikhe
also, i dont wider is always better unless you have the power to back it up. I suggest not running anything wider then 275 if u are NA since you lose alot of speed in acceleration in such with wider tires.
can I see your math for how 275 vs 285 affects contact patch and rolling resistance enough to slow me down?
I wouldn't be running 275s up front if I was drag racing / only cared about straight-line speed anyway........
07-13-2007, 12:01 PM
#37
I'd say there is probably a point of diminishing returns. At that point you would start having slower lap times because you can't accellerate the tires or decellerate them as quickly. I'm NOT, however, saying that 275's is that point because I truely don't know.
07-13-2007, 12:41 PM
#39
If you exit a corner 2.5 mph faster on 285 width tires as compared with 275 width tires you now have a 2.5 mph head start down the next straight. The aerodynamic, MOI, and rolling resistance diference between the two tires won't make up that difference.
On a 3,000+ lb., 300hp race car, you can't have tires that are too wide. On a 1,500 lb., 120hp race car, tires too wide can be a problem.
On a 3,000+ lb., 300hp race car, you can't have tires that are too wide. On a 1,500 lb., 120hp race car, tires too wide can be a problem.