Cobra Nationals - Control Tyre Class

[Kimbo]

Hi Guys,
As some of you would be aware, we have a control tyre class in the Cobra Nationals using the Kumho KU36.

I understand these tyres are becoming rare in the wider sizes these days.

I am up for suggestions on an alternative control tyre that we could switch to in the future.

If we made a switch, there would need to be a time period that the KU36 and the new tyre would both be accepted.

Any suggestions for the successful continuation of this popular class would be great.

Thanks,
Kim

[spookypt]

Kim is the nitto nt05 comparable ish. Not sure what's classed as wide on street cars but 285 is reasonable..

[Tenrocca]

All the following are available in the typical 17" sizes of 275\40-17 and 235\45-17 and are in the same performance category to the KU36 (extreme performance as per tirerack http://www.tirerack.com/tires/types/....jsp?perf=EP):


Nitto NT05, UTGQ = 200 (although some sizes have a UTQG of 140)
Falken RT615\k UTGQ = 200
Toyo Proxies R1R, UTGQ = 200
KU36, UTGQ = 180

Lots of other options with a similar rating up to size 255\40-17, but these are the only ones Ive found that go up to 275.

I know we probably don't want to make it too complicated but possibly going off the UTGQ rating should be considered. Just say tyre must have a UTGQ of 180 or greater? That would really open up the class to nearly anyone less than R-Spec

[David Hodgson]

The treadwear number isn't just a measure of how soft the tread is, it is a number given to the tyre to indicate how long it will last compared to a base number of 100. At tyre with a TW of 420 should last 4.2 times longer than the TW 100 control tyre. Obviously the tread compound has the biggest influence in this, but a case in point: on my daily hack, I recently changed from the RE-002 in Bridgestone's Potenza sport range, which had a TW of 220, to one of the best in their touring range, the Turanza Serenity Plus, which is touted as outstanding dry and wet weather performance - yada yada.
But get this, the TW number is 600. This is partially due the tread being at least 9mm new instead of the average 8mm. I've never seen a number this high. You would think it would be like driving on marbles, but it grips extremely well, though isn't any where near as direct or precise as the sport tyre.

[Tenrocca]

Interesting Dave. I have also found a bit of stuff about how those numbers can be manipulated, but it also looks like there are a lot of amateur series in the US that state a minimum UTGQ requirement for the tyres:

2014/2015 Street Tires (...actually it's 200 treadwear!) - evolutionm.net

We could make it the "180 Class" - which could also mean we tend to spend a lot of time pointing backwards...

[Modena]

Nitto NT05 is probably the closest, cost looks similar too with 275 in 17" looking like under $300

[Tenrocca]

Originally Posted by Modena

Nitto NT05 is probably the closest, cost looks similar too with 275 in 17" looking like under $300

Not particularly well reviewed in this test at least. 2 sec a lap slower than the RT615k over a 57 sec lap time:

Traction Test - The Best 200-Treadwear Tires - Hot Rod Magazine

Not sure why Kumho stopped the KU36 - really was a bit of a performance\value for money standout. I think my current set only cost about $800 and have lasted 3 nats already. Ill "just" scrape one more out of them but have low expectations given they are pretty old now.

[Modena]

Originally Posted by Tenrocca

.....but have low expectations given they are pretty old now.

excuses excuses.....

[DaveW]

Originally Posted by Tenrocca

Not sure why Kumho stopped the KU36 - really was a bit of a performance\value for money standout

Kumho was replacing the KU36 with the V720 and some sizes have already occurred, but the full size spectrum hasn't eventuated.

Dave

[LoBelly]

Having a set tyre in a control tyre class is preferable however I think the reality is that the spread of sizes makes it hard to find a single suitable tyre - like the KU36 - and even if you do there is no guarantee that it will stick around. So the class will probably have to grandfather in a list of tyres.

If your going to have list then you may as well just set up on a parameter like the UTQG. The manufacturers have cottoned on to this being used for vehicle eligibility for a bunch of series - but so what? - if everyone is using - say - a UTQG of 200 - then it will become a defacto standard and somewhat self-leveling.

Personally I like the idea of a UTQG based cut off - I proposed this for Shelbyfest as a cut off determinant but it didn't fly.

Certainly if you compare the UTQG to the 15" parameter for 'Street Class' then the UTQG seems to be a lot more of a level playing field.

Good luck with the quest - if I can get suitable tyres in 15" I might join you

LB

[Modena]

The fundamental problem with the UTQG rating is that it is set by each manufacturer. Yes they decide their own ratings, with little oversight or standards. In my opinion this makes it a terrible comparison between tyres.

Also the traction test is only a straight-line braking test in the wet, there are no dry tests,

Good info here;
Tire Tech Information - Uniform Tire Quality Grade (UTQG) Standards

[Tenrocca]

Originally Posted by Modena

Also the traction test is only a straight-line braking test in the wet, there are no dry tests,

This goes towards the traction rating only (AA-C) doesn't it - not the treadwear number.

My understanding is that the idea of the class was to accomodate those drivers that wanted to have a bit of fun without going to the expense and daily driver limitations of running an R-Spec Tyre. The KU36 was chosen because at the time it was very popular choice and a bit of a compromise between track performance and daily use. It was also widely available online and at tyre outlets so very accessible and relatively cheap

Whilst the UTGQ may not be an ideal way to even out the field, I cant see any tire with a UTQC greater than 180 in our typical sizes that should perform significantly better than the KU36 giving an advantage to that entrant.

If we choose a single tyre going forward, it looks unlikely we will get the same number of people picking that tyre by default as they did with the KU36 - as it was so popular even before the class was devised. So to me finding some criteria that allows a selection of similar tyres makes sense, and UTGQ, even with its flaws might be the best measure.

[Kimbo]

I definitely agree that the control tyre class was set up for those that:

Didn't want to put the extra stress on the car that R spec tyres bring and,

Wanted to be able to compete with their every day tyres so they didn't have to buy a set of "track tyres" just for the Nationals.
This means they have to be happy to drive around on the control tyres all year.

We also wanted to provide a popular class that was able to take cars from the very competitive, fast and oversubscribed, class 3.

The NSW Club is also carrying out some research on this class. I appreciate the feedback this thread is giving.

Thanks,
Kim

[LoBelly]

Originally Posted by Modena

The fundamental problem with the UTQG rating is that it is set by each manufacturer. Yes they decide their own ratings, with little oversight or standards. In my opinion this makes it a terrible comparison between tyres.
..etc...

I think it is true to say that using the UTQG has issues and would be an step down from having a set tyre.

However - It is very easy to pick apart any single parameter class.

Looking at the HotRod article it seems to me that there are a range of tyres that meet the objectives of the class and have relatively similar performance, enabling entrants to make choice that suits them and perhaps allows them to at least get *something* that lets them into the suitable class.

I think by the time you get to the Nationals it will not matter that much to the various class entrants - its basically about being able to have a go against your mates and maybe get some bragging rights (and if you're lucky on the day a plakky trophy)

I think it is better to have a slightly imperfect class than one that is too difficult to enter or run.

ta
LoBelly

[Modena]

Originally Posted by Tenrocca

All the following are available in the typical 17" sizes of 275\40-17 and 235\45-17 and are in the same performance category to the KU36 (extreme performance as per tirerack http://www.tirerack.com/tires/types/....jsp?perf=EP):


Nitto NT05, UTGQ = 200 (although some sizes have a UTQG of 140)
Falken RT615\k UTGQ = 200
Toyo Proxies R1R, UTGQ = 200
KU36, UTGQ = 180

Lots of other options with a similar rating up to size 255\40-17, but these are the only ones Ive found that go up to 275.

I know we probably don't want to make it too complicated but possibly going off the UTGQ rating should be considered. Just say tyre must have a UTGQ of 180 or greater? That would really open up the class to nearly anyone less than R-Spec

these look like good options, although the NT05 doesn't come in a 245x17, and I think the 275 Toyo is not available in Australia, so shipping/currency is something to consider.

I think if something akin to the above four options were presented it gives people a good choice and I don't think anyone could argue that one would be any more advantageous than the other.

[gjkrv8]

My 2 cents worth.

I think we might struggle to get one tyre again like the KU36 that was popular, cost effective, good range of sizes and reasonably available.

A couple of tyre type/brands would be an ok idea I reckon.

Its a great class with some great friendly rivalry. Just look at ShelbyFest this year - we had 3 different winners for the 3 different events.

cheers

Gregg

[Tenrocca]

Any update in this Kimbo?

Had another look at my current tyres, given the rears are now 8 years old and the fronts 6, Im thinking I really need some new rubber come October.

Cheers

[Kimbo]

Hi Guys

The committee has reviewed control tyre class (class 7) and has decided not to make any changes for this years Cobra Nationals.

It has acknowledged though that there will be no choice but to change the requirements for next years event.

[gjkrv8]

Hi Everyone,

I just got word from tyre trader.com that their supplier can't supply my new fronts 245/45r17's as the KU36 is discontinued. I have a massive flat spot on one of them that is vibrating my fillings out of my teeth :-)

bummer - cause these tyres were pretty good and cost effective.

They have offered V720's as thy are the apparent replacement from Kumho.
I've inquired on the V720's for rear wide sizes as I think that may be a problem.

If so then the Nitto's might be our only option?

Has anyone else done any more recent homework on this?

cheers

Gregg

[spookypt]

Nitto NT05 come in some good sizes.