Help w/Best Track/Street Tires Thread for 16"/17" Wheels???

[kjcemo]

TRACK TEST RESULTS​

I opened this Thread asking about the "Best Track/Street Tires for my application. After spending what my wife considers an excessive and irresponsible amount of time I ended up replacing my Falken RT615's with RT615K's size for size (215/45x16 & 255/40x17).

I participate in the Time Trials whenever possible. So my main motivating factor when returning to the Track is the anticipation of improving my lap times (Comraderie is a distant second factor). My last session at Thunderhill was exactly 1 year ago. I have driven this Track over the years in various cars and although the first session of the day was disappointing, it usually is for me. My second session was quite the opposite. I ran a 2:13.594 lap time. I felt like I owned the track until............http://www.youtube.com/watch?v=whCqz6QyqBw

My previous best lap (last year) was 2:15.167. Without going into the car details, its setup, etc. it is basically unchanged. So I am mildly pleased with the results of the 1.573 seconds trimming.

The tires effect on turn-in, braking, G-force cornering is the same as the earlier model with a small but confidence building increase in ultimate adhesion.

Had the Kumho Ecsta XS been available in my size would it have been a better choice..............?

 

[docjohn]

lol that spin was the ol gotta get in front of the slower car without much planning and carrying too much brake into the turn late......nice vid though of how the rear engine car becomes a fulcrum swaying back and forth ...

 

[CL65 Captain]

Tankslapping. :tongue:

You held the correction in too long which is why it came back the other way and thus started the oscillations. There is a moment when you put the correction in and the back end stops sliding and pauses, that is when the wheel as to come back to straight. If you don't get it back straight during that pause, it's coming back the other way. :wink:

To answer you question - is the Khumo XS a better choice. Maybe - but only moderately so. I have driven on the 615s and I liked them, but have not run the XS. I switched to 17/17 and Dunlop Z1 which IMO are better than both.

 

[SlipAngle79]

I am in the same dilemma as the OP was in 2010: I have the OEM 16/17 wheels and I am in need of an "extreme performance summer tire" for a track event coming up the beginning of May. After some research (mainly this terrific thread) I have deduced that I do not want to attempt a 225/50/16 OR it would seem a 225/45/16 will also cause rubbing issues.

Some car background: 91 NSX, Billstein HD's, OEM 91 springs (might change to stiffer before May), Dali street sways bars front and rear, STMPO front bar.

Thanks to nsxtacy for compiling this list of tires that will fit the OEM 16/17's. I have made a few comments based on some of my research as these are what I am considering:

Bridgestone Potenza RE-11 205/45-16 and (245/40-17 or 255/40-17) -supposedly the best option for overall on-track performance, and also the most costly.

Kumho Ecsta XS 215/45-16 and (245/40-17 or 255/40-17) -a soft, cheaper, tire that gets particularly greasy before your 20 minutes is up...(don't all street tires do this?)

Toyo Proxes R1R 205/45-16 and (245/40-17 or 255/40-17) -I've heard they wear like an R comp but don't grip like an R comp, and is this Toyo's wet-weather tire for racing teams that they supply RA1's to?

Falken Azenis RT-615K 215/45-16 and 255/40-17 -I don't know much about these, tell me what I don't know!

This list was posted in 2010, and I must say, nothing has really changed as far as max-grip street tires go that will fit these rims. Unfortunately the RE11A's are not available in a front size to fit.

My questions are:

2 of the 4 tires above come in the 215 front width, the other 2 in 205. Is there really any kind of noticeable disadvantage in overall cornering grip with a 10mm decrease in front width? -I understand one tire manufacturers 205 can sometimes measure out more like a 215 once mounted...I used to track my AP1 S2000 and the 225 S02's in the rear actually measured out more like a 245. I don't know how all of the above tires actually measure out.

3 of the 4 tires above are available in 245 rear width, and all 4 are available in 255 width. Is there a penalty for changing the stagger front to rear, like a 205 front and 255 rear combo? Will this contribute to more understeer or will I even notice? It would seem that Honda ended up with a wider is better philosophy with the 02-05 cars, increasing front and rear width proportionately, though their handling objective may have been to "tame" the "over-rotation" stigma the NSX had, as opposed to sharpening the handling experience? I just sort of assumed I want to fit as wide of a front tire on as possible while increasing rear width in a proportionate manner, am I wrong?

Can anyone chime in that have tried any or all of the above tires on the track? I am prepared to pony up for the most expensive on the list but I don't want to if there is a better option for less.

Eventually I will switch to R comps or slicks but this most likely wont happen until next year. The goal is to have a tire mounted that I can drive in 2-400 miles to the track, thrash on all day, and drive home wet or dry. Therefor, R comps are out for the time being. I have a second car (wish I lived in SOCAL and could DD the NSX) as I live in the midwest :-(, so my NSX is driven 2-3 times a week average. I'm not as concerned with street performance as I am with track performance.

 

[nsxtasy]

Unfortunately the RE11A's are not available in a front size to fit.

That could change. This is a new tire to the market and it's only available in a limited number of sizes. Perhaps they will make a 205/45-16 available as they expand its introduction to more sizes.

2 of the 4 tires above come in the 215 front width, the other 2 in 205. Is there really any kind of noticeable disadvantage in overall cornering grip with a 10mm decrease in front width?

No.

3 of the 4 tires above are available in 245 rear width, and all 4 are available in 255 width. Is there a penalty for changing the stagger front to rear, like a 205 front and 255 rear combo? Will this contribute to more understeer or will I even notice?

Handling issues start to be perceptible when going to a stagger of 60 mm, but I doubt that you would notice any with a 205/255 combo.

FWIW, the 205/45-16 and 255/40-17 combo is actually a closer match to the stock outer diameters and thus the TCS, although that doesn't really matter, since any of these combos will work with the TCS (and you might not use the TCS on the track anyway).

It would seem that Honda ended up with a wider is better philosophy with the 02-05 cars, increasing front and rear width proportionately, though their handling objective may have been to "tame" the "over-rotation" stigma the NSX had, as opposed to sharpening the handling experience? I just sort of assumed I want to fit as wide of a front tire on as possible while increasing rear width in a proportionate manner, am I wrong?

The big limitation with the NSX is the size of the front wheel wells (designed to be narrow so as to permit the pedals and driver's legs to be straight ahead) and, consequently, the width and diameter of the front tires. To avoid rubbing, it's best to go no larger than 215/45-16 (or 215/40-17), although some folks don't care because they're tracking the car (and in some cases have removed the wheel well liners, although that can cause damage - "reverse dings" - to the underside of the fenders).

 

[SlipAngle79]

nsxtasy - thank you, you rock. No, I have not removed the fender liners and I am going to play it safe with the front sizes per your recommendation. So which of the above mentioned tires would you go with? I know I'm not preparing the car to win the GT2 class at Lemans, but its still rather important as whatever I buy, I will most likely be stuck with for the duration of the track season. Are the RE11's the clear winner for track performance? As mentioned, I don't really care that much about performance on the street (whatever that means) because a road course is the only place you can really get everything out of these cars - I would live on one if I could. Does anyone have any on-track experience/opinions on the 4 tires discussed in this thread?

The Captain was kind enough to discuss this subject with me and we both kind of came to the same opinion that the RE11 is worth the money, even compared to the R1R-which is supposed to be more sticky for less $$$ - you end up squeaking 1 or 2 days more out of the RE11's which starts to offset the fact that they are basically a $1000 set of street tires, eek. I also wonder if the RE11's measure out a bit wider than what is printed on the sidewall, similar to the old S02's...maybe its a Bridgestone thing?

As for the car, I plan on setting the Dali street bars both to full stiff (I'm told this will not make any big difference so what the hell), possibly installing Tanabe springs (supposed to be roughly double the OEM spring rate, in the 400ish range?), buying the SOS front brake ducts, pull the butt cushion out for a more secure hold for free, fixing the for/aft power seat switch (only goes back, not forward, I'm thinking its a gunked up terminal), and getting one of those manual seat belt locking tensioners - the kind that slides over the seat belt. Any recommendations? I know I'm kinda off topic with this last bit.

 

[nsxtasy]

I think the RE-11 is the best of the group for track performance, but really, any R compound tire will beat any street tire, so there's that. Also, of the four, they're all quite good on dry pavement, but the Kumho XS and the Falken RT-615K are not as good when it's wet. That may not matter on the track (if you don't intend to go out in the rain) but may affect your drive to and from the track.

The other things you mention are a lot of different things. How much track experience do you have, in the NSX and in other cars? If you haven't driven the NSX on the track all that much, I'd hold off on making significant changes until you get a good feel for the car as is. In the meantime, you can fix what's broken (seat switch) and play around with adjustments.

 

[illwillem]

I've driven the track on the bridgestone Re-111 and falkens 615rtk and R1R. Out of the group I like the Bridgestones best for pure grip followed closly by the r1r- but for the price you can get much more capable tire if thats your only worry.

Best all around price/life/dryperfermance I would say are Azenis RT615K, when new its surprisingly quick for HPDE days, and for the price and avalibility you can beat them. Im currently daily driving take offs from my NSX on my RSX with about 6 trackdays (3 in each car) plus the daily grind on them. IMO they are the best all around of the group as far as cost/performance/wear. once they get down a little past the wear bars on a hot day they start to suck but they are more than fine until then. I have a set of Kumho's on my 'drive to track' rear wheels. I cant say much about them ON the track but my car gets sideways pretty easly with this pair, god know how old they are though.

 

[SlipAngle79]

Yes, I'm probably going to order the RE11's this week and I appreciate your advice. As far as my experience, a 5-day and a 2-day in FF2000's, some series races in the same Formula Fords, at least a dozen HPDE's with some TT's in there (instructed here in STL with the SCCA back in 08), won the A-stock SOLO championship here in the STL region back in 07 co-driving an S2000 on A6's, etc.

As for the NSX, 2 weeks ago was my first time out in one on the track-it was a 10/10ths 3 day at Putnam and it was a blast. Both Captian and DDozier were there driving NSX's and it was truly a gift to have that caliber of NSX owner/track junkie on hand. I had not been on track since 08 and I was just trying to take it slow. I have Goodyear F1's that, to my dismay, I found out after I got to the track that they were actually 10 years old (!). I ran every session the first day on them and it was pretty frustrating, the grip was not there, and add to that I had never been on Putnam. So, learning a new car and a new track on OLD tires, needless to say I was sort of bummed at the end of day 1 but still having fun.

Day 2 and DDozier lends me a well-used set of NT01's (10 track days on them) and that changed everything. Even worn down they stuck really nicely, so nicely I shaved a hard to believe 6 seconds off my best lap on the F1's! I should mention they were 205 front and 275 rear, Dave says "your gonna want to turn your TCS off even driving around in the pits here cause it will freak out". If I reflect on that set of tires, I found understeer on corner entry and I can't accurately attribute it to the extreme stagger or attempting to get my corner entry speed up (as this is what I ended up wanting to work on last) but I am leaning twords the stagger of those tires....which led me to believe I need to either tighten the stagger up on the tires I buy or simply fit as wide of a front tire on as I can. I was surprised by the amount of rear grip the NSX has-I expected more of a nervous twitchy ass end but I guess with the engine back there it makes it stick better? I must confess this is my first MR-had FR's and AWD on the track but never a true mid-engine like this, and yeah this is by far my favorite sports car ever made.

So yes, I would like to have R comps - the NT01's spoiled me, but to be fair a 10 year old street tire is not much to make a comparison to-the rubber was just too oxidized...plenty of tread, no dry rot, but no softness to be found in the rubber. Captain was on Dunlop ZII's and he was turning some impressive times for a street tire (no surprise), which gives me hope that these modern street tires have come a long way in the last 5 years. My friend that I co-drove to win A-stock here in 07 has gone on to become NASA TTC midwest champ two years in a row in his 01 S2000. His take on it is a bit black and white, with R comps being a grey area. He recalled going from RE01R Bridgestones (prelude to the RE11) to the R888 and he was not impressed. He ended up going to a full race slick R6's and got the improvement in time/grip he was expecting when switching to R's from streets. He advised me to just have fun with the car and learn it on good street tires as they are very grippy these days, and when I'm ready for time trial or when I'm ready to trailer the car to events just go straight to slicks. I'm still digesting all of this.

I think you, nsxtasy, are the one who uses the 15/16's with slicks or R comps and you can fit all 4 in the car? This option appeals to me as I wouldn't have to have a trailer and I would also have a viable option in the wet, be it on the track or the drive home while the race tires stay nice and dry in the car. I will say the stock springs on my NA1 are noticeably soft, maybe a tad too compliant-certainly when the NT01's were on. I've heard going to a stiffer spring will give the "feeling" of being faster which can lead to a slight improvement in times but not to expect a huge difference.

- - - Updated - - -

I've driven the track on the bridgestone Re-111 and falkens 615rtk and R1R. Out of the group I like the Bridgestones best for pure grip followed closly by the r1r- but for the price you can get much more capable tire if thats your only worry.

Best all around price/life/dryperfermance I would say are Azenis RT615K, when new its surprisingly quick for HPDE days, and for the price and avalibility you can beat them. Im currently daily driving take offs from my NSX on my RSX with about 6 trackdays (3 in each car) plus the daily grind on them. IMO they are the best all around of the group as far as cost/performance/wear. once they get down a little past the wear bars on a hot day they start to suck but they are more than fine until then. I have a set of Kumho's on my 'drive to track' rear wheels. I cant say much about them ON the track but my car gets sideways pretty easly with this pair, god know how old they are though.

Thank you Sir Willem, this changes things a bit, I was suspicious of the capabilities of the Falkens and the fact that the front size is not narrower than stock appeals to me. Hmm. $664 for the Falkens vs. $798 for the RE11 (255 rear like the falkens)...no, those prices don't include shipping.

 

[nsxtasy]

I think you, nsxtasy, are the one who uses the 15/16's with slicks or R comps and you can fit all 4 in the car?

That's correct.

I will say the stock springs on my NA1 are noticeably soft, maybe a tad too compliant-certainly when the NT01's were on.

Are you sure that this feeling isn't due to worn shocks? Worn shocks are more common and more likely...

 

[SlipAngle79]

Are you sure that this feeling isn't due to worn shocks? Worn shocks are more common and more likely...

No sir, brand new Billstein HD's on the lower perch-had them installed 2 months ago and couldn't make up my mind for a spring-went with 91 springs, figured I would start with what would be the most compliant spring to get to know the car with a little forgiveness. If you refer to the bottom of post #34 you will see the middle photo I attached (was having difficulty uploading) in which the NT01's are on, mid-corner shot from the inside, and I think the body roll is fairly dramatic. Behind the wheel, however, the car felt planted in terms of grip and would take a set nicely (albeit with body motion on the soft side), but there was definitely noticeable understeer on almost every corner-and transitions would reveal some excess body movement (like T3-T4).

I'm trying to figure out what I have already on the car(been following the CT bar thread)-Dali street bars front and rear, but I'm told changing hole position to max on them isn't going to make any big difference as far as the understeer issue-for example if I crank the rear bar up and soften the front, should I not feel a reduction in understeer? I feel like the car needs stiffer springs, but I don't want to be too stiff to preserve some streetability. From what I have researched, the Tanabe's are about double the factory spring rate, which seems totally acceptable on the street opposed to say a 600-1000lb. spring? And if I'm primarily on street tires for the time being, I don't need all that stiff of a spring?

Why does everyone seem to stiffen the front and soften the rear on these cars? 60% of the weight is at the back of the car. The "soften up the rear" approach works well with an FR, but in theory I would think (and what do I know-only been on the track once so far in the NSX) that this approach would contribute to understeer in an MR like the NSX. Maybe the majority of drivers aren't comfortable in a car that has a hint of oversteer at the limit vs. the safer "feeling" of understeer? So then I think: a touch stiffer up front is going to contribute to a more confidence inspiring car in high speed bends, but low and medium speed bends its gonna push? With 60% of the weight at the rear, if you completely even out everything (springs, bars, shocks), shouldn't the car have a slight oversteer at the limit?

And alignment settings seem odd on this car-I would figure neg camber would be priority in the front, not toe out. It was explained to me that since there is hardly any weight over the front axle, the car needs toe out up front to assist with turn in? I can dig the relatively high amount of castor-as this sort of "adds negative camber" once the car is past the turn in phase-or the more the front wheels are turned, the more neg camber is gained? Turn-in just felt to understeer-heavy in my car in its current state, regardless of the type of corner. The T9/T10 complex for instance, I was having to add steering before both apexes, and really this was the theme through out most of the corners at Putnam. But was it the 205/275 combo? I don't know, maybe I should start my own thread here since we're not on topic anymore. I'm not arrogant and I would like to learn from you guys before I buy the next series of track goodies for the car, instead of mistake after mistake to hopefully come to a happy compromise. Thanks for reading.

 

[nsxtasy]

The T9/T10 complex for instance, I was having to add steering before both apexes, and really this was the theme through out most of the corners at Putnam.

Turn 9 doesn't really have a conventional apex where you want to be at the curbing on the inside of the turn; the key to 9 is to turn in and then keep the car balanced as you make your way around, without forcing the car to either edge of the pavement. It's normal to add a bit of steering before the apex in turn 10, around the point where the right edge of the pit exit meets the left edge of the normal track.