INTIMAZY

iTrader: (15)

I picked up a set of 18x9/18x10 Advan RS wheels.
The tires I was looking at were the Kumho V710 or Toyo RA1.
I wanted to run 285/30/18s up front and 305/30/18s in the back with the V710s. I know BS (guess now CS) 350Zs have run 275's on 8 inch wide wheels since a wider tire > optimal fitment in stock classes.
My first question is...
Will a 285 V710 be fine on a 9" wheel? Should I look for a wider front wheel? Should I just stick with RA1s in 275/35/18 for the front?

I know its splitting hairs over 10mm, but I don't wanna ruin the v710s any quicker than they will already wear.

guitarist

iTrader: (1)

I've run 295 V710s on a 10" wide wheel and it looked and felt great. The 315s on the rear (also 10" wide wheels) were slightly pinched and probably not giving much if any more actual contact patch, but also totally doable.

I'd run 295s all the way around. The slightly wider tire is also a little taller, getting you a couple more mph in second. The price differential between 275 and 295 is tiny (like less than $10 usually) and the 295s should be responsive enough even up front. The more rubber the better, really, in my opinion.

Whatever size you get, if it's for autocross, I say get the V710. The RA1s will be well off the pace.

INTIMAZY

iTrader: (15)

Thanks for the input! Yea, its for autox. I was leaning towards the v710s myself. I'm just wondering how well the 285s will fit on a 18x9.

The 18x10 in the rear is within Kumho's specs for a 305 so that's fine. The front 285 prefers a 9.5 according to Kumho. Thats my biggest concern. I've never owned Kumhos so I don't know how they look or behave when crammed onto a rim like that.

I don't see a 295 listed for the 18" Did you run 17"s?

What are your thoughts on a 285/30 front 315/35 rear setup?
I personally prefer a staggered setup. I'm not good enough yet to pull off consistent runs on a square setup. (borrowed a square setup off a mustang for a bit to see how it worked)

PDX_Racer

iTrader: (2)

Ignore the "suggested specs" for DOT-R tires, at least for autocross. If you can get them mounted, then give them a shot.

In my experience:

Do 285/30R18s V710s fit on an 8" rim? They do. Do they work? They do -- at least on the 350Z (a friend tried that size on his RX-8 and he was less than happy with them).

INTIMAZY

iTrader: (15)

Good enough for me. Thanks guys!

racerbob4

iTrader: (8)

We have raced on the Kumho 710's 285/30x18 for the last 5 years. Our front wheels are 9" and rears 10" and they work just fine. I will let you in on a little secret.......don't tell anyone. We found out that the most optimal pressures were 22 in hot weather and 23 in cooler temperatures for the first laps were best. We usually ended up after 20 mintues of qualifying with pressures in low to mid 30's. Don't tell anyone about this please.

INTIMAZY

iTrader: (15)

I'll make sure nobody finds out, thanks! Seems kind of low compared to what I was told over the last two seasons in SCCA but I'll try it out in the spring.

DriveI65

Racerbob4 is road racing not autocrossing. He has time to warm the tires up to temp. You won't.

guitarist

iTrader: (1)

I ran between 32 and 36psi front and 24 and 28psi rear on 275/295 V710s for autocross. Any softer up front didn't seem to help grip, and I was rolling to the edge of the tread surface.

Like said above, you won't have time to bring the pressures up.

I ran those pressures above cold and hot (bled down as the tires heated up). Worked pretty well. You could probably go a bit lower on the fronts if you have a ton of static camber, but if you're in stock class, those are probably pretty good base lines. Also, larger widths on larger wheels seem to like slightly lower pressures than the skinnier tires on smaller wheels.

scotts300

iTrader: (46)

I run 275/40/17s all around, and like to keep the fronts at 29psi hot and the rears at 24psi. I've never tried a delta of 8psi from the front to the back, but you were running staggered and I don't. Maybe that's why.

guitarist

iTrader: (1)

When I was running 275s all the way around, the magic number was typically around 32-36 front, and 30-32 rear. I was on skinny Enthusiast rims (7.5/8"), which might also influence those pressures a bit.

Stillen Z

iTrader: (2)

I have a 2004 Z and I don't see how people get 295s (and even wider, some claim) to fit on the rear without rubbing. I had 295s that rubbed on the inside. I have rolled fender lips and the tire just cleared on the outside, but rubbed a bit on the inside. It couldn't have been an offset problem because I had almost no clearance to the outside. If I had more offset (or is it less?) to move the tire away from the inside of the fender for more clearance there, I would have rubbed on the outside.

I fixed the problem with 285s, but how do you people get 295s and wider to fit under the fenders?

Also, will 265s or 275s fit on the front without rubbing at full compression or full lock?

Stillen Z

iTrader: (2)

Since your fronts and rears were the same size, the OE front/rear diameter difference was eliminated. Did that cause you any problems with the VDC or ABS?

And yes, I realize that in my previous post I asked if 275s will fit under the front fenders. Your posts seem to say that yes, they will. Still, I'm wondering if you had any rubbing issues at full lock or compression. Also, please let me know if you were running the 275s with stock ride height or if your cars were lowered. Thanks.

scotts300

iTrader: (46)

Absolutely. I have run 285s up front on 18x9s with no rubbing as well. I did not specifically test "full lock" though, since I don't need that ability.

VDC does not like the 275s all around - I run with it off. ABS has only given me a problem in tight-turned autoxs while diving hard into a turn and braking. It took me many years to ever experience an ABS issue in autox, I've never had an issue with open tracking ABS (minus braking too hard before the brakes and tires were warmed up fully). My car is lowered quite a bit. I think it's 25.5" from the ground to the top of the driver's tire, but I can check. There is a LOT of room left in the rear for more rubber, but I don't know/don't think I can fit a 295 up front on the 17x10s as it's very close right now.

My track set-up is 17x10 +25s all-around with 275/40 Hoosier R5s that run wide and have a very square shoulder. They just rub under high compression on the outer shoulder. I would need a shorter tire, like a 285-295/30/18 in the front with a gentler shoulder to avoid rubbing with the larger tire, but I think it's doable.

My autox set-up is 17x9.5 +30s all-around with 275/40 V710s. They do not rub at all. I quickly found and copied these pictures - even in them you can see the room in the rear and how low the car is currently.

z33sm2

iTrader: (13)

I have run a 315/30/18 hoosier on an 11 inch wheel with a strong pull of the fender so a 285/30/18 on a 9 inch wide wheel with a proper offset should fit no problem.

A couple years ago I had a 315 on an 18x10 on the back and a 295 on an 18x9.5 on the front with just a fender roll.

scotts300

iTrader: (46)

Do you remember the size and offset of the wheels by chance? And what brand of tires?

z33sm2

iTrader: (13)

The wheels were Kosei K3

The front was 18x9.5 +30 with a 10mm spacer. 295/30/18 hoosier A6
The wheel cleared without the spacer but the buldge of the tire rubbed.
Rolled fender with a very slight pull. -2.9 camber. Ride height was about 2.5 inches lower than stock

The rear was 18x10 +20. 315/30/18 hoosier A6
Rolled fender with -1.7 camber