Wanting to see if its feasible to run 285/35/18 square without having to cut anything or run over fenders or a widebody. Spacers are fine if needed

Info:

Car currently - Lowered about 1 1/4 inches front and 1 inch rear on Koni Yellow Sports and Swift Spec R springs
Alignment - Not aligned yet but thinking of running -3 front and -2 rear
Wheels - Thinking of going with RPF1 18X10.5 +15
Tires - Deciding on a few different brands that offer either 285/35/18 or 285/30/18

Im fine with rolling my fenders if needed for this but if I need to do anything more than that I might just bump it down to a 275/35/18 and see if i can get by. Also curious for 275s if it would make more sense to go with 18X9.5 (same offset) or 18X10 +38

Thanks

 

Totally possible. I have 285/35r18 square on my 18x9.5 +27 and I really like the fitment. I have the rear rolled, but there is plenty of room and the front is rolled with a very slight pull and I have plenty of clearance, even hitting bumps with lots of steering angle. I should have some pics in my thread of it. But


I am running 1.8 front and .75 rear camber. Michelin PS4S.

 

Sweet. Was worried I was going to need to spend a bunch more money making things fit after buying wheels and tires. Is you car lowered at all?

Also my z is the same color!

 

Just a word of caution... 285s will fit but if you opt for +15 offset, likely will need to roll the rears. I ran 285s on "regular offsets" of 22 and above but as soon as I put on a set of 9.5 +15s with "only" modest 275s, scraped on speed bumps. Nothing major, just annoying. Rolled and sealed the rears, I now run 275s and 285s down at +8 with stock range alignment.

These are 10.5 +22 with 285s post roll & seal

 

yes, on KWs. I used to be super low, but got tired of that and am dropped about 1-1.25” now.

^This is important. The +15s will require more effort to fit and will have more contact. That is half an inch less clearance than I have with the +27. The +15 will be a tighter fitment for looks, but I drive my car like a sports car should be driven and I would have rubbing with a +15 if I did not pull the fenders more or run more camber.

 

Oh, one more thing, forgot to ask/mention…

Does your car have VDC? If so, you might want to re-think square setup due to the POSSIBILITY of false triggering due to the lack of front-rear speed bias which causes the ECM to think the rear’s stepping out.

No VDC, no issue. Possible minor issue with TCS but not likely. I never triggered it running 275 square.

 

That’s one of the tire combos I ran. It did require over -3 front camber , but it’s also needed to utilize them properly on track

next, look at the tires. One of the tires I ran, the 275/35 was actually wider than the 285/35 , doesn’t make sense (cheater tire ) and the 275 was a couple pounds lighter.

so yes it’s possible, just look at all options and look at specs.

 

Sorry for late reply. Yes my car does have VDC. I was a bit worried about it but I see people have mixed results with VDC so I'm kind of on the fence. Im mainly using my car for autox and would eventually like to work up to the track. No real street driving but maybe from time to time My logic was to fit something big to avoid going too small and wishing I had something larger. Though we'll see if that pans out. If there are better options for my application or suggestions I am all for hearing them. I am relatively new to all of this so while I do try and do as much research as I can before hand, opinions and knowledge from people who have been there and done that help a lot.

 

I do however have a big ol' VDC button I can press on and off. It pressing the button actually turns VDC all the way off and prevents this problem then I am okay making the wheels fit

 

275/35-18 is normally a better option, but always look at specs.

VDC does not disable the system all the way, disabling the yaw sensor will do that. Then some people do run into abs issues from going square

 

Seems a little wishy washy if these sensor issue will bite. Would you still recommend running square and just dealing with these issues if they come up?

 

OK, just my opinion here but NO, I would not. Disabling VDC entirely makes it difficult to put back to "safer mode" with VDC unless you're going to be installing switches and the like to the yaw sensor, which is acceptable but again IMO, I wouldn't.

There's another reason to consider... if you're autocrossing, you *MIGHT* be able to get the tire temps up to optimal range but 285s take a while to heat up so if your region/sanctioning body doesn't do back-to-back running, tires are going to cool down between runs. Put this way, even in long time/distance hill runs, my 245/275 setup never even reached 140 no matter how hard I pushed them, barely enough to give them adequate bite. They still worked well but could be better. Pyrometer doesn't lie. Maybe in track use you'll see the needed 160+ but street/autocross, strongly doubt it. Just a thought to consider.

I also don't care much for what square does to steering response (street tires that is). Maybe if you're running DOT gumballs like a RE71R or 888, they'll be better but I've found that the large contact patch up front dulls the response and I have a strong preference for steering input response at the possible expense of ultimate grip. But again, that's my preference only. FTR, I run my cars with stock alignment range (down near max camber), 38/34 air pressures F-R, and bars biased to stiffer rear (hole 1 front, hole 2 rear) to promote a tad bit of oversteer. Just matches my driving style better. YMMV.

And that brings me to another point. You will need big sway bars and a fairly aggressive alignment to keep those 285s where you want them. As terrasmak mentioned, he runs a fair bit of camber - believe on his track car - to keep them under and stopping rollover. You'll want to consider the hardware necessary to allow for that type of alignment setting and final tuning through bars and/or spring rates.

 

Yeah and that was another concern of mine. Actually heating the tires. After sleeping on it, I think it might just be best to use my stock wheels for now or maybe see if I can find a set of the OEM Rays and run staggered sizes closer to what you posted above. Would take out a bit of the hassle and not to mention at least some of the cost away from trying to run big wheels and tires. A sway bar is on the list but not something im planning on doing now. And dialing in spring rates is not a rabbit hole I want to go down at this time. This type of thing might just need to wait until I decide to take things a bit more seriously and track the car.

I might just run the next season's autox events and then make a more informed decision about what I need. IE decide whether I want to go whole hog on this 20 y/o car

Thanks for the input everyone!

 

Mic makes some great points here. I have found a very overlooked aspect of the vdc issues is the wheel offset. When I was running spacers, and when I had my wider front track width with the lcas I had vdc issues. With out them I do not have any vdc issues unless I am on track and in those situations my yaw box is on a switch to fully disable it. The heat thing is an interesting point. I could get mine so hot I was having to spray the tires between rounds, but I am in the gulf coast and we would regularly have asphalt temps in the 110s+.

I run a stiff front bar and loose rear bar. A stiff front helps keep the front at ideal geometry, and the soft rear helps with corner exit. Its been so long that my car had stock suspension, diff, or bars that I don't completely remember what is was like.

I do second the number feeling up front with the wide square setup. Its a bit hamfisted, but these cars are front heavy and I think you will find autocrossing that you are eventually going to want to shove as much front tire as you can. A pyrometer will confirm that though and you can make an informed decision tracking temps and behavior with any setup and using that to pick your next set of wheels and tires.

 

And thats the dilemma I was having. Wanting to buy once, cry once as they say rather and spend the money on smaller sizes, regret it down the line, and have to spend X amount more to go wider. Wheels im looking at are +15 and i do not plan on running spacers unless its needed which I dont expect from what ive found

I am in the midwest so temps in the summer can get HOT but during the start or end of the season temps are much milder. Ive been to a few events with the car already and with my second car and noticed what some of the other guys are running. Lots of guys running 300+ section tires so clearly there must be some merit to it (most of those are the older guys who have been around. SCCA sanctioned events btw).

The VDC issue is my real sticking point as it seems like it is really hit or miss. I guess one way to find out. If I need to set up a switch to disable the sensor then so be it.

 

Well, if all of this is too be believed, then the setup I want should satisfy VDC after checking things with a size calculator. Though this is just a forum post from years ago.

https://my350z.com/forum/wheels-and-...read-here.html