How much pressure should I run in my 275/35-18 Hoosier A3S04s?

Following some great input, I mounted a set of 275/35-18 Hoosier A3S04s on some 18 X 8 wheels. They fit surprisingly fine on the wheels. Since the wheels have a 35mm offset, I've added some .25 inch spacers, no rubbing on the front suspension at all.

But I'm surprised at how much air pressure some of the local folks have been running in their Hoosiers. Scary high air pressures. But taking the advise of a local national level competitor, I put as much air in the front, as my 11 gallon bottle let me (53lbs) and balanced out the rears with 44lbs. The front really responded to the higher pressures... in fact, I'm thinking even more would be better. The rears never really lived up to my expectations. It was a cold morning... but the tires did not allow me to make much use of the Z's torque.

There were only 5 of us in the class, a father/son team in a Boxster placed 1/2... I trailed in 3rd place by .32... and a couple of S2000s behind me by .6+. So my finish wasn't too bad... looking at a total of 165 participants (all classes), I was 36th. I had plenty of opportunities to improve my driving performance. I just had a difficult time getting used to the difference the tires made to the car.

In my search for the optimal wheel/tire set-up... every step of the way, I faced resistance from people selling me the wheels and tires I wanted... I based my purchases on input from folks on this site... a BIG thanks to the membership! I was told by TireRack that the tires wouldn't fit... I really didn't get any expert advise from my sales representative. The web site I bought my wheels from removed all of their recommended fitments for the 350Z after I ordered my wheels... and slapped a disclaimer on my order saying the fitment was not recommended... after telling me the wheels would fit and saying the manufacturer had verified the fitment. My tire mounter was concerned as well... they called TireRack... who fueled their concern... but following my willingness to sign off responsibility... they were excited about putting their latest mounting machine to the test... and getting some hefty revenue off of it. So I called the wheel manufacturer... they all A/X Miatas and actually chuckled about all the liability disclaiming from TireRack and the tire mounter... they said they all run way more tire/wheel ratio than what I was proposing... and the wheels were a no brainer... they were right... the 275/35-18s fit on the 18 X 8 wheels without any real noticable "pinching". The tires look like they are meant to fit that narrow wheel. You'd have to see it to believe it.

I have to admit, I had moments were I was questioning the wisdom of following the input I received on this site; however, the experts here on this site were right on... everything worked fine. I didn't notice any wierd ABS problems during this first event on the tires... but that is probably related to my not making the most of my new found grip.

Oh, one last observation... I loaded all four in my car... along with my 11 Gallon air tank, flight bag, floor jack, folding chair... and tooled off to the event... no trailer required. Do I need a trailer? You bet! Has anyone come up with plausable hitch solution? Maybe L8Apex's design will work with my Stillen exhaust... I'll have to do more investigation... it looks promising. But until I get that sorted out... I can fit it all in my Z.

Adios,

Brian

 

Lateapex's design looks very simple and I like that. I doubt you'll find something better.

I ran 49psi front and 37 rear hot last weekend for my Toyo T1S. I liked 49 front but not sure what to do with rear. It still sliding easily... and I can't seem to go any lower judging the tire wear.

So how exactly did you fit it all in Z? I know I can put two wheels on passenger seat (very tight thought), and one in trunk... WHere the forth one go?

 

i fit 2 in the hatch.

pull the spare. put one under the strut bar. put one over the strut bar, resting against the seats and on that plastic peace where the 2 rear speakers are.

 

The 275/35-18s are about 10" wide... I don't know how that compares to 17 inch wheel/tire combos... but you can't get one to slide under the strut brace...

Wheel 1: In the spare tire cavity... elevates the mat a few inches.
Wheel 2: On top of the rear speakers, up against the back of the Driver's seat.
Wheel 3: Stuffed high and behind the passenger's seat.
Wheel 4: In the passenger's seat, on top of the air tank... like a crown.

I might leave the air tank at home from now on... once I get my tire pressures nailed.

Brian

 

Carter and I run 46f/43r on 275/40/17 S04's.

 

BACulter,

Nice post and an even better job at dispatching those S2K's.

The Force is strong with you. We will be watching your progress very closely.

 

Tomsn16,

Thanks for the information... have you heard of anyone running pressures in their 18s?

Brian

 

Drivesolo,

I'm hoping to get some practice in on Saturday... you'll have to take it for a spin. You'll freak on how much difference the Hoosiers make!

Brian

 

I went to 265's all around and am now having problems with the RE being very loose. Was told to toe in the rear 1/4", and toe out the front 1/4" to resolve the issue.
I ran 245 front and 275 rear before and the rear was not a problem. Also did a 5-6 # differential, toe out 1/4 up front and that worked well.

 

rktjhn,

Thanks for weighing in on this subject. Do I understand correctly, you went from 245/275 Hoosiers to 265/265 Kumhos? Are you thinking the staggered sizes were a better set-up? I'm very pleased with the grip in the front. I have my 350Evo bar set on the middle setting. The front tires stick well but have little tolerance for big input... must maintain smooth input. Out back, I'm at odds... I'm not able lay down the torque because the back tires just don't hook up.

Yesterday, I was able to put in 6 six runs on a very short course (less than 26 seconds), as a benefit on helping with a club driving school. I ran with 60 lbs up front, 54 lbs in back. I need a pyrometer!

I still haven't encountered any braking problems... I'm not getting the most out of the tires yet either. Nailing the brakes after the finish lights, the brakes generate massive amounts of stopping power... with the ABS barely working.

I'm waiting for the Koni's to arrive (been waiting for quite a while), to have the alignment set. The 1/4" in front sounds like a plan... Did you try the 1/4" toe in rear?

Thanks again,

Brian

 

What tires were they on?

Bringing A3S04's to local events is usually like bringing a gun to a knife fight... or something

 

ellisnc,

Up here, anything other than local events entails a major road trip... Seattle to San Fran (10 hour drive) or further. Our local events usually draw 175+ entrants. The local BS competition is at least equally armed with Hoosiers and Kumhos... not to mention a couple of extra years of set-up development. At the NWR SCCA Solo II events, CS/BS/ES run as a class called "S2"... a PAX factor makes winning the class that much more difficult. So I'm bringing a gun to a gun fight. None the Zs up here even have a set of shocks yet.

We're still experimenting with the Z set-up for A/X. We are fortunate enough to have some local nationally competitive drivers to use as sounding boards. Joe Goeke runs his S2000 in the Pro class and he's way faster than all of us running in BS. I think we're making reasonable progress with setting up our Zs, and we'll do reasonably well.

Brian

 

Good on ya then

edit:
Wish I had some nationally competitive drivers that ran in my classes in my region to compare myself to. S2000-BS and WRX-SM.

Closest guys we have are Danny Popp in ASP (who is freaking out of his mind btw if you've seen him drive ), Jason Tipple, Todd Meade, Jeff Robinson, Alex Schipkov (sp)

 

ellisnc,

I think I remember Danny Popp being a hot FS driver years and years ago. I also watch other national level drivers in our region and PAX 'em out to try to judge where I'm at. Do you have any 350Zs running with you in BS?

Brian

 

No, there were a couple that have been out but they weren't serious. Again... I don't like PAX locally when everyone isn't prepared to 1" of the rules for their class and aren't on equal tires.

I have been running SM in the WRX because there's more competition locally. A couple times last year, I ran BS in the S2k and beat a couple others on race tires. Either I'm fast or they're not... probably the latter.

I guess the whole conversation started by someone being happy you beat a couple S2000's locally. I've seen HS Civic's and Foci beat B-stock 350's with drivers that didn't know what they were doing in the Z's. In my mind, locally, doesn't mean a whole lot for the reasons I've stated unless you say who the drivers are. If you say you beat a couple with good drivers who brought their equipment that day - good on ya In my experience and from what I've read about the S2k, unless you're running against a guy with Penske, JRZ, Moton or some other damper like that, the stock suspension is fine. Throw a front bar on if you need one and some tires, alignment and let the driving do the talking. Everything else is just the last 5% which locally, the better driver can easily make up for. Doesn't take long to fine tune that setup - minus some trick dampers... can't imagine the Z would be too much different due to the nature of the Stock class rules. IMO somewhat - the Z has been out for a couple years now right which should be enough time to show it's potential. Goodness knows enough people have them.

I hope a Z does place in the top 3-5 this year in B-stock... maybe that way the S2k won't get the boot

anyway, back to the tire pressure thread

 

I hope the Z does better nationally as well... but not quite for the same reasons as you! Take care.

 

Guys, thanks for the input on the pressures.

I've been running my Kumho Ecsta V700 (265/35-18 all around) with 37 in front and back. I've been rolling the edges on the front pretty good, so I'll go add another 5 psi to see how that does. A while ago when I asked a similar question about pressures, someone was telling me that he was running in the high 20's, but I don't see how that's possible. Anyhow, thanks again for the point of reference.

-D'oh!

 

D'oh,

I'm thinking there are two ways to get our tires pressures correct: 1) Use a pyrometer (requires spending money and finding a victim... strike that... crew member to check temps) 2) Ask around. Obviously asking around seemed to be the path of least resistance. Besides, what do you do with a pyrometer after you get your pressures dialed in? Other than give it to the neighbor kids for rodent control purposes.

I've gathered an appreciation for just how different one brand of tires can be from another. With my stock RE040s, I ran 35/28 FT/RR, the Kumho guys sound like they run 47/41 FT/RR, Toyo T1-S is 45/39 and my Hoosier S04s seems to love more air pressure period... I'm afraid to go beyond what one of our local Pros said he runs in his S04s (he's driving a BMW 330). I'm holding at 60/54 FT/RR. The fronts love this pressure... the backs feel like they're just along for the ride. They are behaving well in terms of balance to the front... but they don't appreciate liberal doses of gas pedal being pushed at them. They just break loose.

I'm going to have to find a pyrometer and some kind person to take the readings for me.

Brian

 

Seems like we have a bunch of people with experience in this thread!!

WOuld someone mind giving me a little pointer on a starting pressure for the Nitto 555RII (I wanted to try something different). I havent run them yet, and they are also my first pair of R-compound tires, any idea where to start on a G with hotchkis sway bars set at full stiff (58% stiffer) front and full loose (64% stiffer) rear bars?

I am thinking of just starting at 35 psi all around and adjusting from there. Does that seem like a good starting point?

 

Well, it would seem that pumping up the pressure a bit over stock is a good bet, just to help stiffen things up a bit. Maybe go 40 in front and 35 in back and see how that does. You have pretty wide tires, which would typically mean you could run lower pressures, but since they are mounted on a somewhat narrow rim you may want to keep the pressures up a bit for starters and see how the edges wear.

-D'oh!