[t-ray]

Tomorrow I'm autocrossing my 1LE for the first time. I never had a chance to autox my '18. This is my first autox in since 2012 (2011 Mustang GT), and the last time before that was in 2006 I think (2005 G35). I'm used to rwd cars, but this car is bigger than my others, slightly heavier, and make much more torque.

I don't know what class I'll be in. The previous owner put in an aftermarket airbox, but that's the only mod that I know. So I think that puts me in STU? Regardless, I won't be in a stock class. The car has inferior aftermarket tires (stock size), so I'm not going to be competitive no matter what.

It's going to be warmish, but likely wet. This group usually has some high speed, less technical courses. Can someone recommend some starting air pressures for a fully stock suspension/stock alignment car?

Other than tire pressures, anything else I should think about before tomorrow?

[Xyebo]

I do 30 PSI if its cool outside and 28 PSI if the tarmac is warm. Just be aware that Goodyear Supercar 3 tires will take at least one run to warm up, so be prepared to throw your first course time out.

[t-ray]

Yeah some of my tires on my old cars were that way. My current tires are nitto NT555 G2's, and they are far inferior to the SC3's just on the street.

[Scargoes]

When I had Conti ECS on the stock wheels and just the GM performance alignment, I ran 32-34psi in the front and 30-32psi in the rear. I would bleed off pressure between runs. It seemed to work pretty well for the asphalt surface I was running on.

[Msquared]

Honestly, if the airbox is your only mod, I'd ask if you can just run F Street. I would never protest someone for just that, even at a national event (it's worth anywhere from 0-1hp). Eventually, just put a stock airbox back on it if you decide to keep autocrossing. STU is not going to be your friend if there are any serious builds in there, and CAM-C (where most modded pony cars gravitate) is wide open and will cost you lots of cash (but it's fun). So I'd try to stay in F Street for now, at least.

The Nittos are bad tires, yeah. For those tires (not the OE Goodyears or a good autocross tire), I would suggest more like 33psi if it's wet and 35psi dry. I think they will need all the help they can get from the higher load capacities that higher pressures create.

[AZIROC]

On my SC3s, id air down to around 22 cold(ish). When I was done with a session (and if possible during the session using the info center) id check the psi. I try to keep it right around 30-32 psi hot. usually by the end of the 2nd session I have it dialed in.



As for as nitto, I couldn't tell you but id guess around the same 30psi. Maybe 35? Hot.

[joelster]

F-street or CAM-C, F-street will be better for you. I run 31 front 30 rear for pressures. I'm running competitive tw200 autocross tires. Road race tires will likely want different pressures. I have no experience with them for autocross runs.

[t-ray]

Ok, they kept me in FS. I started with tire pressures at ~32psi, and monitored them but they never got north of 34psi in the front. Rears stayed fairly cool because they never really moved.

I don't have a ton of experience; I attended maybe 6 events between 2005 and 2007 (g35), and once more in 2012 (mustang). So they put me in novice? Regardless, I'm disappointed in myself and in the tires. The front just pushed all day. I was stunned by the lack of front end grip. I'm sure that's just as much my driving as it was the tires; I know I was being stingy and braking too late. I have to re-learn to brake earlier and harder.

But it was super fun. I'm seriously considering buying a set of oem tires and getting a track alignment just for next month's event.

[Msquared]

Originally Posted by t-ray

But it was super fun. I'm seriously considering buying a set of oem tires and getting a track alignment just for next month's event.

To do it truly right, you need true autocross-focused tires. The stock SC3s are great track tires and okay autocross tires, but a proper set of Falken RT660s is worth at least 1/2-second off the Goodyears, and Bridgestone RE71RSs are worth at least another 1/2-second (and I think I'm being conservative). You need 19" wheels to get the better tire selections here.

You also need more than the track alignment in the manual. You need all the camber the stock front and rear suspensions will give you. Zero the toe in front and run a teeny bit (1/16") in back. In back, that toe setting will be the limit on how much camber you can get. You should be able to get around -2.7 up front and -1.9 rear.

[t-ray]

Thank you for the advice. I do not plan on competing regularly, and I want to stay in f-street, and plan to stay stock for a long time. So that means sticking with the stock wheels, and I think the SC3's are probably my best overall autox+street tire option there.

[Msquared]

First, let say what I forgot to add to my last reply: it's great that you got back out there and I'm glad you had fun!

Originally Posted by t-ray

Thank you for the advice. I do not plan on competing regularly, and I want to stay in f-street, and plan to stay stock for a long time. So that means sticking with the stock wheels, and I think the SC3's are probably my best overall autox+street tire option there.

SCCA rules allow all Street classes to change wheel diameter (but not width) by 1" up or down. So a 6th-gen SS 1LE can legally run 19x10s in front and 19x11s in back, which helps with tire selection a lot. This is what almost every serious FS competitor does if they drive a 1LE. Also important: you can deviate from stock offset by up to 7mm in either direction, which helps with wheel selection a lot.

That said, if you are truly constrained to running the same tires on the street as you use for autocross, and you drive significant street miles, that does change the calculus for tire selection. The Goodyears will last longer on the street than an RT660, RE71RS, Nankang CRS, or Yokohama A052 (these are all the fast autocross tires right now). IME, they don't actually last longer when autocrossing them. But if you run, say, three events per year then they may be a good choice. And they sure will be a crap ton faster/better than those Nittos (they are truly bad tires, really). And the Yoks are the only other fast that comes in decent sizes for your stock wheels, and you definitely don't want those if you want tires that last.

Before you commit to this plan in any material way, make sure you can actually get those Goodyears. The rears at least may be backordered right now.

[clyde]

Originally Posted by t-ray

Thank you for the advice. I do not plan on competing regularly, and I want to stay in f-street, and plan to stay stock for a long time. So that means sticking with the stock wheels, and I think the SC3's are probably my best overall autox+street tire option there.

If you're just going to dabble, the SC3s on your stock wheels should be fine and it's probably not worth spending extra money for an extra set of wheels and tires.

If you change your mind and might run with some regularity and want to get competitive, be aware that Street-class rules allow going up or down 1" in diameter from stock. Nearly everyone competing nationally in FS is on 19" wheels (maybe everyone? I didn't look this year).

[ariZona28]

You might want to stay in Novice for a bit untill you're feeling comfortable and more competitive.
Another good dual purpose tire to consider is the Michelin Pilot Sport 4S. I have those on my Z/28 and they worked great during my feeble attempt at Auto X. I started them at 29 psi ( it's REALLY HOT here) and kept them around 30 or so if I recall correctly. You can do the old school crayon trick (my C5 Z06 is pictured) to check the sidewall/tread wear mark. Wearing to the top of the triangle is a good starting point. Not an exact science but helps get your tire pressures in the ballpark. Depending on how much you drive it on the street you may want to leave the alignment alone until you really go all in.

[Msquared]

Originally Posted by ariZona28

Another good dual purpose tire to consider is the Michelin Pilot Sport 4S. I have those on my Z/28 and they worked great during my feeble attempt at Auto X.

These are a definite step slower than the OE Goodyears. However, they have the advantage of being world-class rain tires and work well in cool temps (at least down to freezing, probably lower). They also will last longer and be quieter and better riding than the SC3s. So this comes down to a tradeoff between outright performance on a warm/hot day (SC3) vs a much better very-high-performance street tire (PS4S).