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.

Maximum grip? 255.

You may have fitment/rubbing issues depending on your setup though.

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.

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.

https://fbcdn-sphotos-e-a.akamaihd.n...04985561_n.jpg

..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

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 :)

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.

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)?

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.

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

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).

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.

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.

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?

Street Modified, or Street Prepared for that matter.

I think wide 15" wheels don't fit because of the tie-rod ball joint.
http://www.ft86club.com/forums/showp...1&postcount=19
http://www.ft86club.com/forums/showt...836#post495836
(I thought about running 16" wheels but the 17" wheel rim tire combination actually produced the smallest diameter in a reasonable tire size).

I guess I should pay more attention. Thanks for the heads up.

What's "best" has too many variables to provide a definitive answer; even for just autocross. The ideal tire width depends on the class you're shooting for and the rules of that class. Certain classes have wheel width limitations which in-turn affect what would be the ideal tire width. This is further complicated by the performance category and brand of tire you use.

If you have more specifics about what your racing plans/goals are and the classes you're looking to run, it might be easier for us to give you advice along those lines.

Running 215 Michelin PSS (stock suspension and engine) and I feel like it's not enough tire. I'll probably try running a 225 or 235 next.

Can anyone chime in running a 225 and 235 tire on the OEM wheels? Does the 235 tire fit at all?

When you say it's not enough tire, is this for HPDE, AutoX, or just street driving? Also, in your consideration for a wider tire, are you wishing to stick with Michelin PSS? A 225 or 235 tire will fit on a 7" wheel fine, but whether it provides better performance will depend on the brand/model and driving application.

80% HPDE, 20% street. pretty much only street miles are to/from events. After driving on PSSs, RS3s, Star Specs, RA1s, R888s, AD08s, NT05s, NT01s as far as "streetable" track tires, I have actually come to like the PSS the best overall for the various track conditions we get down here in FL. I do about 10-14 HPDE events a year with the BRZ, and SCCA regional club races with a Miata.

PSS is certainly a great tire. I run 215/45/17 for daily driving and rainy autocrosses and love them (I like Rivals and RS3s for dry). The sidewalls of the PSS are stiff enough to handle using a 225 on stock sized wheels, but I wouldn't go wider than that.

Just picked up a set of 17x9 et38 for a killer deal ($350 shipped brand new from discount tire direct) and will be testing out a 245 PSS in the near future with it, and will report back.

For SCCA Street class, would you run 16x7 or 17x7 light wheels, and with what width tire?

The easy answer is just to run 17x7 wheels and 225/45/17 tires. Pretty much all the "extreme" and "max" performance tires come in this size, so you will have plenty of options to choose from.

Alternatively, you could run 16x7 wheels and 225/50/16 tires. Again, most tires in the "extreme" and "max" performance categories come in this size as well. Generally speaking 16" wheels and tires are cheaper, so that is a plus, but a 50 sidewall tire might feel a little sloppy and not transition as quickly as a 45 sidewall tire.

There are a few other sizes you could consider depending on the tire brand/model you choose (like 225/45/16 or 235/40/17), but a 225/45/17 or 225/50/16 will give you the most options.

My wheel spec is 18x9.5 +40mm offset for all wheels. Rays Gramlights 57Xtreme. Tires 255/35-18 Pirelli P Zero.

I have done some research but didn't find a definitive answer for the best setup for track days and need some advice to choose the most suitable width for front and rear. I'm also planning to get semi-slick tires.

If I go for narrower front at 235 is it going to be more nimble and reduce roll resistance? For the rear I'm planing to keep the 255 width for more grip.

Need advice on this please.

I'm trying to on a proper tire size for track use on a Vortech supercharged frs. I see many people have gone 17x9 with 245 width, but then again I see some people suggesting a narrower tire/rims for better times.
In short, i currently only have budget for a new set of rims and tires for track use but would like to get the proper size for a FI application, anyone out there that can offer some insight? Thanks!

Most people are running Toyo R888 in the street tire class around here (slalom (autocross) and hillclimbs).
I was curious about potential competitors, as I need new tires in spring.

In this review the Toyo R888 was beaten by all competitors: http://trackparts.ch/images/pdf/semislicktest%2012.pdf
(It's also interesting to note that the R888 is a pretty heavy tire in comparison)
Especially in rainy conditions the Pirelli P Zero Trofeo is faster than any other semi slick tire, which was also confirmed by the last review.
The Pirell P Zero Trofeo is available in 205/45 R17 which could be one of the quickest 17" semi slick option in a wet slalom event (autocross).
(Neither the Michelin Pilot Sport Cup+ nor the Continental Force Contact are available in any 17" dimension.)
(However, the Toyo R888 has never been a good competitor in the rain: http://trackparts.ch/images/pdf/semislicktest%2005.pdf)

In dry conditions, based on the following review and based on some online forums the Dunlop Direzza 03G should be faster than the Toyo R888, however it is only available in 235/45 R17 as opposed 235/40 R17. I'm not sure, whether the tire could make up for this gearing disadvantage.
http://trackparts.ch/mediafiles//Pdf...ktest%2013.pdf

Also, there doesn't seem to be any information about the Dunlop Direzza 03G on US forums (it is probably not being sold in the US).

(All these reviews are unfortunately in German, but if one has a specific question I can translate.)

I tried the R888 in the 205/40 R17 dimension.
In the last wet event I still dealt with hydroplaning but I was significantly faster than the competitors on wider tires and was even reaching maximum lateral accelerations of 1.1 g (and lost only half as much time to the guys running on non-road-legal racing rain tires).
However, in a dry event these narrow tires became greasy relatively quickly. I lost 3 seconds compared to last year on 235/40 R17 on a 3 minute long course.

So which is faster in 20min. HPDE session, driven by a seasoned intermediate driver (let's say Buttonwillow 13CW 2:05)?
1) 215/45R17 NT01 or equivalent
OR
2) 225/45R17 RS3
I believe they both heat cycle out and it is getting cold so getting and maintaining heats in the tires are not so much of a problem. I'm thinking of trying 215 but wanted to know if it is even worth the effort...

thank you

the extra 10mm of the RS3 wouldn't even come close to offsetting the greater performance from the NT01.

That's a fact.

Nice thread!

Let's say you are constrained between:

- 215/45 AD08R on 17x8

or

- 225/45 AD08R on 17x7.5

Which one would you choose for hpde?

Please, keep in mind that 225/45 on 17x8 isn't possible (not road legal) :(

Thank you!

Tire Width?
 

If you put 225/45/17 on stock wheel, make sure you put some camber in there. & it's better to run tires a little stretched.


Sent from my iPhone using Tapatalk

- 225/45 AD08R on 17x7.5 should be faster
- 215/45 AD08R on 17x8 would feel better

Depending on experience, you might think the car is sliding from the "floating" feel you would get from a tire that is wide on the wheel (the 225s here) and not push it as hard out of fear, in which case 215 would yield better times. If learning and/or having fun is primary objective instead of lap times for bragging rights, then choose 215.

Que? Lolwut?

I'm hoping something is getting lost in translation. What kind of rule would keep you from putting that combo on the car and driving on them?