Comments on S Specs.

[Tony]

I guess like many others, I've searched the Forum from time to time looking for information about motorsport tyres. While there has been lots of useful information posted, there really hasn't been a definitive thread that pulls all the info together.

That was until Randy's Comments on R Specs thread; and what a pearler it's turned out to be! It will be a great resource for those searching in the future.

For a number of reasons listed below, my interest has been in a group of tyres that are now being referred to as "S Spec's". So rather than hijack Randy's thread, I though I would start a complementary, piggy-back thread in an attempt to pull together a range of experiences and comments. Hopefully this will also provide a useful reference for future searchers. Also for future reference, I should mention that there's plenty of good info in Guran's thread here: http://mx5cartalk.com/forum/viewtopic.php?f=68&t=42619

I'm not really sure where the colloquial term "S Spec" came from; they are often referred to as Ultra High Performance or Extreme High Performance tyres by the manufacturers. Basically these tyres are aimed a club level enthusiasts, and attempt to bridge the gap between street tyres and what is pretty much a straight competition tyre (ie. R compound).

While S-Spec tyres obviously won't offer the same levels of grip as an R Spec tyre, they should be quicker to warm up (good for hillclimbs!), should not be affected by heat cycling (or to a much lesser extent anyway), will perform better on a wet road/track and will last longer than their R Spec cousins. I've also heard that S Spec tyres have an arbitrary treadware rating of 100 - 200 and you don't get a choice of compounds. Examples off the top of my head include Falken RT615, Khumo KU36, Yokohama AD08, Dunlop Z1 Star Spec and Federal 595RS-R.

My car is predominantly used for club events, but I don't want to get involved with two sets of wheels and tyres (...well not yet anyway!). So I wanted a tyre that I could use to drive to the track and also use for occasional weekend trips, without heat cycling out. I also wanted a tyre that could cope with cold weather at home and overnight in Goulburn (it was minus 7 degrees here this morning!) and one that was safe enough for the wife and kids to use in the rain if they had to.

I initially ordered a set of RT615s, but after three weeks the local dealer still didn't have them. With a club day at Wakefield looming, the only tyre I could find on the rack at short notice was as set of 195/50x15 Federal 595RS-Rs at Gordon Leven's. They cost me $180 each.

I was sceptical about using Chinese tyres, but had no alternative. Gordon recommended 36psi hot and I've been really surprised by their performance so far. Grip has been very good and when they start to let go it's very progressive and easy to control. They're reasonably quiet, both on the road and when pushed on the track. They work well on a wet road (with limitations), but I've no experience on a wet track as yet. I've done four track days and travelled around 6,500kms with no real signs of wear. They are great bang for your buck!

Would I be prepared to buy them again? Absolutely! But variety is the spice of life and I think I'll try the Yoko AD08 next.

What have been your experiences with S Spec tyres? What's been good and what's been not so good? Has anyone tried the AD08s?

[NMX516]

I've recently fitted some KU36's as track day tyres, and have done one track day on them, and probably 1200kms on road. I'm pleasantly surprised, having previously used Toyo 888's for the track.

The KU36's haven't shown any sign of distress, and worked quite well on the track. They got me around the clubman circuit at QR in 1:07's, so they're not too bad. I found them predictable, and to break cornering traction gradually. I've only encountered light wet weather with them, and they seemed ok. Downside is the road noise - nothing like the 888's give, but I wouldn't like the KU36 as an everyday tyre. I have a hardtop on at the moment which I suspect may highlight the road noise a little.

Perhaps something worth mentioning in this thread is that so called S Specs require less "science" than R Specs, and by that I mean, storage, rotation, pressures, alignment etc etc, aren't as critical as with an R Spec - I suppose what I'm saying is that they're more user friendly and fool proof. A better "beginner's" track tyre.

As a good "bang for buck" track day tyre, the KU36 would be fairly hard to beat I would think. I paid $160 each for 205/50/15, which is half the price of the 888's; but the 888's don't offer twice the level of grip.

[Randy]

I think this is a good thread to start.

I currently use Kumho KU36s on my NC as my 'track' tyres. I have to say I'm very impressed with them. Firstly they've lasted the full ten rounds for the season, and I probably have another two track days left in them. They are outstanding in the wet, while in the dry I've found them to have excellent grip and are very progressive when they start to lose grip. They do go off after about eight laps, but even then they maybe less then half a second off there optimum performance.

Time wise around Winton long track my best time with the standard Michelins was a 1.49.3 while with the Kumhos my best time is a 1.44.3. Around Phillip Island my times dropped from a 2.03 to a 2.00 whilst Sandown netted a two second improvement too.

So for $185 in a 205/45/17 I think they represent the best value for money. I'd definitely recommend them to anyone.

[KIJIMA]

Advan Neova AD07's are a bloody good thing and you can get them in some suitable sizes for the MX5, AD08's you cannot.

[broady]

I've only had one proper drive on them but my Bridgestone RE-11s are absolutely fantastic.

[Tony]

Yokohama Advan AD08 in 205/50x15 are $280.00 per tyre from the good folk at Gordon Leven's.

I've had similar experiences with both Toyo and Bridgestone where their web sites don't necessarily list all the sizes they have available; particularly when shopping for odd sizes such as 205/55 and 245/45 x 16 (obviously not for the MX5!).

The Toyo R1R is another tyre that could arguably be classified as an S Spec. Toyo describe it as a motorsport inspired, ultra high performance passenger car tyre.

[broady]

Look to Tire Rack. I priced up a set of AD08 in 15" and it came to something like $750. $250 goes to postage. (USD)

[broady]

Advan Neova AD07's are a bloody good thing and you can get them in some suitable sizes for the MX5, AD08's you cannot.

You can if you look overseas. 205/50/15 is available, I know this much.

[Mr Morlock]

tyre reviews always come down to - "for what purpose". There is no tyre which will be ideal for both road and track- there is going to be a compromise. I can well understand why guys have 2 sets of tyres. Many people also factor in cost- pretty normal- as how much ones spends on hobbies or road vehicles is tempered by other financial demands.

[deviant]

Toyo say the R1R is suitable for buffing and will offer more grip when this is done...I.E. The less tread these tyres have the better they get! I would think the tyres would have a very stiff construction if they are designed to grip more and more as life goes on.

[Benny]

I've been using RT615's for a few years now, and I'm very happy with them.
They grip well and make the car feel very secure.
I've tried some hi-po Kumhos, and was very dissapointed with them as they made the car feel very loose and squirmy.
So much so, that I changed all my rear bushings, and it didn't make much of a difference, so I took them back and got another set of the RT615's and the car felt great.

One thing I do like abut the RT's is that they are very quiet on the road, unlike some other tyres I've tried and Tempe tyres do them quite cheap too.

[broady]

If you're considering a new set of RT615s, wait for the RT615K, it's supposed to be on par with newer tyres such as the AD08, Star Spec and RE-11 unlike it's older counterpart.

[Tony]

For the benefit of future searchers, I'm including this link to a rather excellent recent discussion regarding the Kumho KU36:

http://mx5cartalk.com/forum/viewtopic.php?f=30&t=39176

[Guran]

Ha! Look what I just found ...

Dec-2009 Drivers rave about new tyre

Reports are now coming in on the performance of the new DUNLOP tyre; Direzza Sport Z1 'Star Spec'.

Ray Monic fitted 195/50R15 Z1's to his MX5 (shown at left) recently and has just reported:

"I was out at Phillip Island on Sunday last week and had a chance to try the new Dunlop DZZ1'S in both wet and dry conditions.

In the wet I was highly impressed with the traction of the tyre. Even with really wet conditions the confidence it gave me was fantastic due to it's stability and balance. I managed to post some quick times, so much so I had some of the MX5 boys coming over to see what I was running on.

In the dry I managed a personal best time, the tyres came on progressively as I pushed harder and the exit of corner grip was very good and because of this it took away the understeer that I was previously experiencing. Under braking these tyres are very responsive. Also the tyres wear like a racing tyre so much so they even picked up rubber from the track and showed no signs of feathering on the tread of the tyre, normally a big problem with road tyres on the track".

http://www.stuckey.com.au/news_200912-02.aspx

[StanTheMan]

My first "S spec" tyre was a RT215. It blew me away. I raved on about that tyre endlessly on here. LOL, Very unrefined compared to the RT 615. It needed warming up on the street. you couldn't push it for the first 2 or 3 corners before it warmed up. But when it was on temp. My god. the grip. the stopping power were insane. I loved that tyre. You could say patchy, Myself the tyre were the perfect set. I dove & drove those tyres endlessly. at Wakefield, Putty road, the old pack Club runs. & touge runs.

Then the RT615 came about. Couln't wait for a new set. Waited & waited for the 16" size to come out in Australia. It never did. So I sold my 16" rims reverted back to my old 15" rims & wrapped them in the RT615.
Very disappointed compared to the RT215. Yes it was a more refined tyre. in magazine tests it was quicker than its predecessor ./ around the racetracks......But it was just too refined. They killed a lot of its character.
Yes it still does have plenty of grip. Nice hard sidewalls. bit less noisy, & no warming up required on the street. Yes I gave it the same treatment as the previous set. I would be in heaven.....If I was given another set of Rt215's. Its been the most exiting tyre I've had to date.
I doubt I'd ever get another set of Rt615. They really killed it by making it more mainstream acceptable. Yes the RT215 had issues. But I had accepted those & drove accordingly. The RT615 was supposed to be a better tyre. Not in my books.

Toyo R1R. I've had it for 6 months. I haven't been able to give it a serious thrashing. Probably because I've become to sensible. Doesn't need warming up. sidewalls are a bit softer than the RT615.I Haven't been to the track. haven't been up Putty or the old pack. Or any club drives. So in hind sight.....I really didn't need to get them. But I did because just incase i do get a chance. But then....it will probably be wasted because. as I never go over 80% on a first go with an unfamiliar tyre.