Better 15/16 or 17/18 for R-Comps ?

stuntman said:

^225 is too small for an NSX IMO. Let us know how they work for you!

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Eh I know my friend but that's what they had! Videos of my (possible) shenanigans in the NSX will flood my youtube channel soon...!
I am also adding a NSX-R front swaybar so this will make the handling a new experience..

Hey, sorry for chiming in late here, but I ran the NT01 in 15/16 last year to see if I could "get away" with them.... there is no comparison to the 17/18 setup on these cars. I was able to buy NT01's in 225front 245rear, allbeit with a 50 sidewall in back (!) and in terms of wear the rears were corded on the outside shoulders during my second event. At the time I had old Dali street adjustable bars on front and rear, KW V3, and CT camber kit in front at -3 camber, max at rear (-1.8). I actually was competing in NASA Time Trial (TTB) and was hoping the setup would last as I could free up points to use elsewhere on the car. I was able to score two 2nd places in the first event with that setup and missed out on 1st by .7 sec to a stripped and well setup E36 M3 so my feelings weren't too hurt, however I knew were the time was hiding - in the banking where it was difficult to commit to 100% throttle the whole way through, in part due to the narrow foot print the 15/16 carries. In terms of the handling feedback, the 15/16's were pleasant, no surprises other than reaching a lower limit vs 17/18, but even with a mostly stock engine I was experiencing power-on wheelspin in 2nd exiting some corners.

The only thing I would caution you about is the potential for some serious rear tire wear, if it wasn't for that I might have tried to keep going with those sizes, but in the end I made the switch up to 17/18 NT01 (same sizes as DDozier) and never looked back - use your imagination, there is a HUGE improvement in overall grip, everything gets better: turn-in, braking, traction on-power. I was able to get my first 1st place in TTB with the 17/18 setup and no other changes at that point, at a new track, with fuel cut issues, and against a pretty quick local in yet another E36 M3 (they dominate TTB FYI) Its good that your running that size because if you make the decision to step up to 17/18 you will have a big grin on your face within the first 3 laps of your first session on them. I learned the car first on 10 year old street tires on the track on a stock car and developed it from there so its been a nice evolution were I get to experience each modification and feel/reference on the lap timer the improvements, that is if I don't do a couple of mods at the same time (which I always seem to do ;-). I went back to that track I first was on with the 15/16 setup now armed with 17/18 and a proper GT wing and crushed my old lap time by over 2 seconds, mostly from the wing but also the bigger wheel tire setup... I did run it on another track I had run 15/16 on WITHOUT the wing and 17/18 and the car was noticeably more stable with a higher grip limit everywhere, besting my previous time on that track by a little under 1 sec. Good luck and enjoy your NSX!

SlipAngle79 said:

Hey,[...]luck and enjoy your NSX!

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Thanks for your feedback! well for the price of one and a half rear 18" NT01 I bought 4 tires so that alone made financial sense

I put them on this past weekend and test drove it around town just for fun. I can definitely feel the rear having less traction. This is my first time trying some 200UTQG tires on the NSX so I do not have benchmarks in terms of laptimes.
My car is a 1992 and currently has Taitec and DC headers, no idea of the hp.

Bonus picture for dog lovers

I noticed that with the 15/16 the rotors get less air and my brakes go out sooner than with the 17/18 RP-01 that I have previously used. It makes sense as they are pretty chubby and cover most of the rotors.

I think that with R-comp on 15/16 and upgraded stock brakes you can go pretty fast and far. Enough for some trackevents per year. You can learn and increase your skills.

I suggest to make the folowing mods to match the increased grip of the tires :

- coilovers
- bigger sway bars
- châssis bars
- brake fluid, pads and cooling ducts
- maximise front camber

With that you should have something consistent (<- most important thing).

And when you reach the full potential of this setup, you can go with 17/18 rims, BBK, non-compliance stuff, front camber bushings, ... (never ending list).

The R888 are available (in the US ???) in 225/45/15 and 245/45/16 which, I think, fit the stock wheels. Or, if you can fit the stock wheels in teh car, go direct with full slicks. Personnaly, I do not find the slick tires to be unprogressive.

asylum said:

The R888 are available (in the US ???) in 225/45/15 and 245/45/16 which, I think, fit the stock wheels.

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No, they don't. Not safely, anyway. Toyo says the R888 in 225/45-15 should only be mounted on wheels 7.0-8.5" wide, and the stock front wheels are 15x6.5. (The 245/45-16 is approved for widths of 7.5-9.0", so they're okay on the stock 16x8.)

I haven't looked into tire selection on the nsx, but I'm wanting to do a stretched tire setup. I'm running a 245 on a 9" wheel on my s2000. I like how the car handles versus 255 on a 9" wheel. But i have a feeling the limited tire selection for the nsx will prevent me from doing that.

Not sure if this helps, but this where learned of stretching tires.

https://www.facebook.com/notes/holl...d-track-day-tire-faq-utqg-140/245008598916447

Optimal wheel sizeMany folks entering the ST category are refugees from Stock looking to make some performance upgrades to their car and/or reduce their tire budget. Unfortunately, they carry with them some baggage on concepts that may work well in Stock, but not in ST. One of these is optimal wheel/tire fitment.

Since Stock limits you to the OE wheel sizing, astute competitors have learned how to stuff increasingly wider tires onto those skinny rims. And tire makers have been happy to make wider and wider tires, likewise charging more and more money. But, is wider better? In Stock, the answer is often "yes". The sidewalls on these DOT-approved "Not for Highway Use" R-comps are super stiff and allow for "overtiring" much in the way that a cantilever style slick works to get around wheel width limitations for formula cars.

In ST, drivers in most classes have limits on both wheel width and tire section width, both of which are much wider than OE. The tendency is to cram the widest legal tire on the widest legal rim that will fit and go for it. But that is not always the optimal solution, as street tires do not have the same super-stiff sidewalls as do the best R-comps. Sometimes it makes sense to run a narrower tire for a given rim fitment. From the testing we've done, we find that a good rule of thumb is that the optimal rim is the same size (rounded up to the nearest half-inch or so) as the tread width (not section width!). So a 205/50-15 tire with a typical tread width of 7.5" is best on 7.5" rim. An 8" rim will work, too, but it will be majorly stretched on a 9. Likewise, it will lose some performance on a 7, and will lose a LOT going down to a 6 or 6.5. Similarly, a 225/45-15 with an 8.2" tread width works best on at least an 8.5" rim and loses a fair bit on a 7.5".

A practical example of this is in STC, STF and STS where the rim limitation of 7.5" keeps the 195/50-15 Toyo R1R at the top despite it not being the widest allowed tire size. The 225/45-15 R-S3 mounted on that same 7.5" rim is not quite as fast. But put that same R-S3 on an 8 and it comes alive. And it's even better on something a bit bigger. So in STR, where wider rims are allowed, the common 225 R-S3 on 9's is a faster combo than the 195 R1R on a 7.5 (assuming nominal weather). And putting the 195 on an 8 or wider does nothing to enhance performance and close the gap.

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You can use wider tires on wider wheels. But it's a VERY bad idea to use wider tires on wheels that are too narrow, or too wide, for the tire. The reason is, when you do that, it creates excessive stress, and heat, in the sidewalls, and it can lead to tire failure (e.g. blowout). And if that happens, the tire manufacturer can deny warranty coverage for the failure, due to the tire not being used according to the manufacturer's specifications. (And there's also the significant possibility of driving off the road and having an accident.) NOT a good idea.