Tire Width?

[qoncept]

Originally Posted by overlookedx

Hmm this thread has me reconsidering what width I should go with. I have 17x9 RPF1s on order, and was going to get 255s for track, autox, and occasional DD/spirited driving. Now I'm not sure.. recommendations? I thought 225s would be too much of a stretch for a 9" wide wheel? I'm not looking to be competitive or anything, just to add as much grip as I can from a wheel/tire upgrade.

I wouldn't put a 225 on 9" wheels. 215s look pinched on the stock 7" wheels, and I had to very reluctantly settle on 245s on 9.5" wheels on my WRX. If you want to go with 225s I'd change the order to 8" wheels.

[CSG Mike]

The front stack is 225/45/17 BFG Rival on 17x9 TC105N. The rear stack is 225/45/17 Hankook RS3 on 17x8 TC105N.

Is the 225 on a 9" stretched? Yes. It's not TOO bad with a EHP tire, but would I recommend it to the average joe? No.

[naikaidriver]

..yet another thread full of WIN!

Thanks for the insights guys. Your experience seems to fall in line with what I have been observing in the autocross paddock as well.

Scott

[Element Tuning]

This is a tough one for me to say one is exclusively better than the other on the FRS/BRZ. It seems like weight and diameter have the largest impact on the performance of a low power car. So on tracks that are tighter and require more acceleration is seems 275 or 285s that I run really bog the motor down. Now on the really high speed/momentum tracks it seems the larger contact patch has the advantage if you can get the actual speed up high enough and then take advantage of better braking.

I will say it was not a problem to get heat in the front but getting heat in the rear was a challenge NA. Now that I'm high downforce and boosted 285 slicks are barely enough

[Unobtanium]

Alright, I guess let me ask a simple question. I have very limited track experience, and I want to run a good street tire like the Michelin Pilot Super Sport. I do not want to change any component of the suspension other than tires/rims at the most. My use for the car would be daily/street driving. The kinds of corners I see on my daily commute are going to be like a watered down version of Spring Mountain Motorsports raceway in Pahrump. I drove that in a Corvette, and found that the track simulated many things I encounter daily, just way more aggressive.

So I guess answer my question like you would were you going to race that track.

What rim/tire should I run for optimal performance. My driving style is about moderate regarding using the tires. I try to enter corners wide, make full use of the exit curbing, etc. rather than relying on the tires to grip hard and use a shorter total distance traveled with earlier turn-in. However, more grip is nicer, especially for the street.

I am going to be moving to the Fayetteville, AR area, and there are a LOT of very nice iconic roads, such a "the hog trail", etc. that I want to have some safe, sane fun on.

[rx3]

I was thinking about running narrower tires during wet conditions while autocrossing, since this should get the tires to heat up to a greater extent.
In wet conditions the guys who are running on rain racing tires are significantly faster than the guys on street tires (their compound is grippier at lower temperatures). In dry conditions the gap between the guys on racing tires is smaller compared to the guys on street tires (semi slicks).

Do some autocrossers in the US run narrower tires in wet conditions (street tire class)?

[WolfpackS2k]

I can't directly answer your question, but in general narrower tires are always better than wider tires in wet conditions. It's easier to evacuate the water the tire encounters.

[Robbie]

Originally Posted by rx3

I was thinking about running narrower tires during wet conditions while autocrossing, since this should get the tires to heat up to a greater extent.
In wet conditions the guys who are running on rain racing tires are significantly faster than the guys on street tires (their compound is grippier at lower temperatures). In dry conditions the gap between the guys on racing tires is smaller compared to the guys on street tires (semi slicks).

Do some autocrossers in the US run narrower tires in wet conditions (street tire class)?

Yes, narrower tires can be advantageous in really wet conditions.

[rx3]

I got a set of 205/40 17 for rainy days.
I think they should be better for 2 reasons:
1. Better water displacement
2. Higher rubber/tread temperature (I think this should actually play a bigger role)
(Besides these tires are also lighter and increase rpm/speed).

[7thgear]

water displacement should only be an issue if you're running through puddles.

which means thas sum 'evy rayne.

for light rain/drizzle i wouldn't bother chasing deamons by putting on narrower tires.

[rx3]

The thing is this: The guys in the racing tire class are significantly faster on rain tires than the guys on street tires (semi slicks). Much more so than in dry conditions (racing tire slicks vs street tires). This is because they are running a compound which is getting grippy at lower temperatures.
Now, since I don't have the option to run racing tires in my class, I still have the option to run a smaller tire which is reaching a higher temperature than the larger tire (which is barely reaching 25 C in rainy conditions).

Keep in mind: It's not the tire width that is responsible for the grip, it's the coefficient of friction between tire and road and this coefficient of friction is primarily dependent on tire temperature and this temperature is primarily dependent on the size of tire (e.g. a wider tire is under less stress and has more area to dissipate heat).
A friend once mounted wider wheels/tires on the front axle of a racing kart to see whether this would increase grip. He actually lost grip in the front, because the large tires on the front axle simply wouldn't get up to temperature.

[celica73]

Anyone thinking of trying 275/35-15 Hoosiers on 15x10 wheels (would they fit...)

That's about 3/4" of lowering without compromising the suspension geometry at all. They are also kind of fat and sticky I'm thinking mostly in the forced induction arena. Raising the rev limit (autocross) would probably be a must.

Just thinking out loud here.

[7thgear]

Originally Posted by celica73

Anyone thinking of trying 275/35-15 Hoosiers on 15x10 wheels (would they fit...)

That's about 3/4" of lowering without compromising the suspension geometry at all. They are also kind of fat and sticky I'm thinking mostly in the forced induction arena. Raising the rev limit (autocross) would probably be a must.

Just thinking out loud here.

which class do you propose to be in with 15X10 wheels?

[celica73]

Originally Posted by 7thgear

which class do you propose to be in with 15X10 wheels?

Street Modified, or Street Prepared for that matter.