M1Cruiser

I've looked into this and it seems like people on this forum run the 315's but Hoosier says the 295's will work a little better because the wheel is pulling the sidewall in on the 315's and that decreases the contact area. Has anyone tried both in autoX? Need to run stock wheel size for the class I want to run. Opinions please.

RDnomorecobra

That's a 9.5" wide wheel correct? If so I agree with them, 315 is too wide. 295 might even be a little wide for that wheel.

M1Cruiser

18" x 9.5" is the stock front wheel size.

Datawiz

I run 315's on my stock front rims ALL of the time. Occasionally, there is a VERY slight rub on the brake duct, but other than that, the wider rubber has yielded much better lap times for me. I stiffened my front shocks and they don't rub. I run between 20-25 events per year in my car.

If you zoom in on the picture, you can see how much they stick out from the rim.

FWIW, this is an autocross setup.

SLandstra_Z06

I have 3 sets of track wheels:

• Stock set
• CCW 9.5 inch
• CCW 11 inch

I have tried the P315/30ZR18 Hoosier R6 and A6 on the stock 9.5 inch and the 9.5 inch CCW wheels. The 315 is too wide and is pinched in substantially.

The 315 is perfect on the 11 inch CCW.

Go with the 295's on your stock width, 9.5 inch, wide wheels.



Steve

Datawiz

Steve,

I hope you can make it back to Fort Myers sometime to run my car with me. Would kinda make the memory of Frank all that more special. I'm pretty sure you and I would go 1-2 in my car, just like you and he did before.

SLandstra_Z06

That would be fun. I'm going to be in Naples from November 19-26. Flying in on the 19th at 10:00 (Ft. Lauderdale) and out on the 26th at 5:20 PM from Ft. Lauderdale. Anything scheduled in Ft. Meyers on Nov. 20?

Steve

Everett Ogilvie

I run the 315s on 11" rims (have never tried them on a narrower rim). There's "optimal" and "acceptable" if you know what I mean. Hoosier recommends 11-12" for this tire, but that would be the optimal category I suppose.

Datawiz

Fort Myers is the weekend before and Dec 4/5.

I'll see if I can find something for the 20th, maybe on the East Coast.

Craig

Kubs

I have 4 front wheels I use as my track setup with 275/35s on them. Honestly I think the 275 is the widest that will work well on the wheel. A 295 might be ok, but the width you gain in going from 275 to 295 will get lost if the sidewall is pinched and rounds the corner of the tire.

Here is a picture of the 275 when I was test fitting it on my camaro:







You can see in the last two pictures the 275 is already wider than the wheel itself.

exracer28

Are you autocrossing or road racing? Autocross might do OK with the 315 but with road racing I would stay with 275, 285 or 295 depending on your setup. I am using that ssame wheel with my 305 rain tire.

Datawiz

Makes a HUGE difference. OP said AutoX.

I've seen more and more of the National Tour guys using 315's up front lately.

Everett Ogilvie

Just for my own learning when you guys say it makes a huge difference; specifically, are you each saying one should not use the 315 for the road course? Just asking, because I think a lot of guys are. Or, are you more referring to that size tire on a narrow wheel? Thanks.

RDnomorecobra

I was referring to that size tire on that narrow of a wheel. Hoosier recommends 11-12" wheel width for the 315/30. Generally I see people go one step outside a recommendation but not further. Meaning putting that tire on a 10.5" or 12.5" wheel. 9.5" seems a little outside the window if you know what I mean. I dont autocross so I cant speak to whether that makes a difference or not. I do road course HPDE and I wouldnt put that tire on a 9.5" wheel. No lack of differing opinions on this one ...

95jersey

Try a 285 Hoosier. If you look at the specs, it is wider than the 295 and will work better on the 9.5" rim than the 315.

drivinhard

275 on a 9.5" wheel

Aardwolf

I have a few events now on A6 295/30/18 and they work well. Fitment is fine on the 9.5" C5 rims that I use. I can take a pic if you want.

joenationwide

Exactly.

To answer this question you need to talk to Sam Strano, since he is going to win SS in 2012 in a Grand Sport.
Autoxers running in Super Stock (SS) have much different restrictions that road racers/TTers.

SS forces you to run stock wheel sizes, with no restriction on tire size. You will see a lot of National level people running retarded size tires on skinny wheels (I think DS Integra ITRs run a 275/35/15 A6 on 15x6.5" wheels!!).

You do not want to run such large tires on skinny wheels on track. But for autox, sometimes it has been proven to be a faster setup.

Kubs

Im thinking maybe the sharper/ more harsh transitions in an atuox environment may benefit from more rounded shoulders (from putting a wide tire on a skinny rim). In RR you do not want to round the shoulders at all as that reduces contact patch and overall grip.

Datawiz

My focus is autocross. 315's vs. 295's equal about 1/2 second for me on a .45 mile test-n-tune course.