Fab_vr6

I ran on brand new RA1 275/40/17 all way around yesterdat for my track day, but I felt the car was underpower with this set up comparing to last year when I had 245 all around, I am thinking they might be too wide for track days. Are they too wide for track use?

Being unshaved and brand new, they were slippery too... At the last session, I set cold pressure to 32 (In the begining when I set it to 36 cold, the pressure went up to 46-7 after the heat), is that a correct pressure?

Fab

tmak26b

Run 32-34psi on the Toyo, thats what i used. What size rims do you have anyway?

techcontrol

iTrader: (4)

I run PS2s 245/40/18 275/40/18 with Hotchkis TVS. I keep the pressures at 35. After a 20 minute session the pressures are at 39/40 and the car is remarkable

commasense

I sure hope not, because that's my exact setup for this year! I'll let you know after my first track day this Thursday. How long have you been tracking the car, and how many track days have you done?

Yes, start around 32 and get to around 40-41 hot.

John

iTrader: (17)

275s aren't too wide, that just means you're not moving fast enough. Wider tires can be slower if you don't drive them right - so overdoing your steering input will scrub off speed much faster with your larger contact patch.

Where you able to put a good heat cycle into the tires before you used them? If not, then your tires will likely heat cycle out prematurely.

Your cold pressures will vary, but I usually started around 29-31 depending on the ambient temp (if it was 30 degrees, then I'd start around 31-32). You ideal hot tire temp should be 39-41psi on the RA1s...

Fab_vr6

Thanks for your info John and sorry to hear your mishap...

I think you are right, I am not moving fast enuf, I still take corners at the same speed as when I had narrower tires. I guess I am not taking corners fast enough. By driving them right, do you mean by this?

Fab_vr6

17"

Fab_vr6

I've done 7 track days last 3 years, including 2 @ PIR. This year I'll probably run 3 more times there...

John

iTrader: (17)

Well, that's sort of what I meant... wider tires can benefit you greatly, but unless you use them right, they can also really slow your car down as well. You'll really be able to use them in the braking zone and scrubbing off speed on turn in - however, you need to get on the gas with them sooner otherwise the additional friction you're getting is only going to slow you down.

first350

iTrader: (24)

I usually ran 32 psi cold...they would be around 40 psi hot. (weather was usually around 70-80F)

the goal was always 40psi hot...

Kolia

iTrader: (2)

28 Front -29 Rear psi morning cold is it's going to be 70-80F. Less if warmer. It goes down to ~40psi by the time I get to the pits.

I run 255/40R17 front and 275/40R17 rear.

first350

iTrader: (24)

I run the same sizes...when I was first looking to buy these tires, lots of track guys were saying to run staggered tires b/c they prefered to have a bit of understeer (rather than oversteer); but for autoX guys, they all run the same size for all 4 wheels (less high speed turns, and more need for quick turn in response/drip)

-Peter

sakred

iTrader: (4)

275's all around are perfect for an NA Z. i personnaly run around 28-29 psi cold and it usually gets upto 35-38 psi hot. also you shouldnt be fooled into thinking your slower cause of these tires. with the 275's you have a higher tire break away point. so just because the tires are not making any noise or close to the break away point doesnt mean your not going faster. a lap time comparrison would be best, and i am willing to bet even though you feel slower. your lap times are the same if not faster then before. i have also ran 275 hoosiers all around and they tend to be a bit wider then most tires the car actually felt more responsive and nimble, i guess that can be attributed to the sidewall of the hoosiers, but in any case do you have your laptimes from before and after the new tire setup?

Hammad

Kolia

iTrader: (2)

Everybody has is own opinion and a preference on tire size. Which one is the absolute best will depend on driving style, car setup and track layout. Frankly, it's pretty much irrelevant since we're only doing HPDE with no lap timing...

And if we were racing, we'd be limited by the class rules.

275 all around or staggered 255/275?

I try to keep my electronics happier by not messing too much with tire size. Plus, on a relatively stock Z, I'm not sure the added front loading made possible with the wider front tire would be much more fun. More suspension travel with the car's bump steer and caster will make the car pretty lively on corner exit. I don't know.

I'm assuming anybody running R-comp has at least a damper upgrade?

Oh, and driving on rails is boring to the max. I'd rather take 20 seconds more per lap playing on the limit, semi-drifting every corner. I'm only running r-comp so the tires can last a full 25 minutes session without going greasy on me. Nothing to do with lap time.

Whatever floats your boat...

tmak26b

nope, bone stock running 235/40/17 on RA1s. I do plan to use a set of 245/45/17 to set some new lap record this year.

Fab_vr6

Lap times are almost identical before and after 1:37-38 range.

Eagle1

iTrader: (2)

What front camber are you running? With 275's all around you should consider running 2.5 to 3.0 negative in the front. That extra rubber will really bite. What temp to set cold depends on the track and the ambient air temp, but I like 31.5 on the Toyo/Nitto, and adjust up or down depending on the other factors.
Frankly, moving up to that rubber and matching your best times, is a good sign. You will get used to them and start pushing the times down.

daveh

iTrader: (9)

Everyone has given you good advice above, but I want to add one thing. Full tread toyos are downright scary for the first 2 days. The slipperyness you describe in your first post may very well be due to tread squirm.
Give em a couple more days and they will be just fine.

Fab_vr6

Thanks so much for all the advice guys! What a group of cool people to be around with.

I have -2.7' F and -2.2' rear. Should I run these tires on the street or highway for the next month or so before my next track event hopefully to wear them down a bit?

On my other post, I have asked a question about trailbraking in the Z. How's everybody's experience in this? I prefer to be able to brake a bit later and trail the brakes into the corner but I never purposely did that on the Z from what I've been hearing ( I guess I will find out if I just try it, but I want to see what you guys think).

daveh

iTrader: (9)

I would only wear them down on the street if you're competing for times. Otherwise just use them on the track and be aware that the squirming is normal and will get better. Typically a shaved toyo is 2 seconds faster on a 2 minute road course, but if you're not being timed, who cares right?