KU 31 vs KU36

[Apu]

I know this has been covered but I'm sure someone will ask the question again, so thought this might help if someone searched for this.

A bit of background - my 2003 NB had Federal 595s on them when I picked up the car last year. I found them noisy plus being 16s, I really wanted 15s so I bought new rims and fitted KU31s. I wanted a sporty-ish tyre that wore well on the street and KU31s seemed to fit the bill.

The KU31s were very quiet on the street and rode very comfortably. On the track, I guess I quickly reached the limits of the tyre (ahem...) to where I was not comfortable with the progressiveness. Let me explain that a bit - the KU31s were great for me as I was getting back into track driving. I needed a tyre that was progressive, that gave plenty of warning, and the KU31s fit that bill. However, in the last couple of track outings I found that I was sliding a bit too much for my own comfort so didn't dare to push much harder lest I run out of track.

At the recent Circuit Club track day, I was running about 10 seconds behind Alex so we jumped in as passengers in each others cars. My feeling was that Alex's car on KU36 had significantly more grip and that allowed him to be much more aggressive in the turns. If he started sliding, he'd back off and/or correct and the car would regain grip very quickly. I couldn't do that in my car as the car would take a bit longer to regain grip and return to the desired line. That said, Alex is much more aggressive and pushes his car a lot harder...I just don't have the confidence to do that.

Anyway, decision made and I sold my KU31s after 5000kms and popped a set of KU36s on. I did contemplate a set of S or R spec tyres on a second set of wheels...but figured I would be too lazy to keep changing wheels and having the hide a second set of wheels around the house...too difficult.

Immediate impression is that the ride is a bit harsher (most likely due to stiffer sidewall), and there is just that little bit more tyre rumble - not intrusive, but you notice it.

So my view of the KU31 is that they are great as a daily tyre - quiet and more than enough grip on the road. However, if you plan on tracking your car, get a second set of wheels or don't bother with the KU31s.

Can't comment on grip and feel of the the KU36 on track yet, but we all know the KU36s will grip better. Question is how much more time I will gain! I'll get some impression at Marulan, and then look forward to the next Wakefield track day!

Perhaps Alex would like to comment on his impressions of the ride in my car? (but keep the comments about my pansy driving to PMs)

[zero00]

Apu

Good choice!! I have just put my second set of KU36's on my NB8A, previous did 16,000km and 325 'track laps', Lakeside & Queensland Raceway

The rears were almost 'street illegal' but the fronts still were around 65%+ Note: I ran considerable 'toe-in' on the rear which maybe enhanced the wear. The car has NEVER broken out with the rear, never had a spin or come close, I pedal it pretty hard but I know I could go faster just that age precludes!

I have some 'Youtube' videos posted, just search 'MX5#141' includes one wet track day at Lakeside where a 'twitch' lead to nothing!!

I have found 35psi cold excellent and speaking with Option 1 Garage in Brisbane where I buy them, was told start 34psi or more, no lower

That's my 'two-bobs worth', I know others will have their opinions and I respect that

Maybe a little noisy but who cares? It's Roadster not a Lexus!!

[Apu]

Thanks for the tip on the tyre pressures zero!

As for the noise, it really isn't very noticeable over my exhaust. My wife went for a ride and I suspect she felt something was different but didn't pick it.

[zero00]

Apu

My NA has new 36's front and the 'old' fronts from the NB on the rear - no tyre noise but it does have S/Steel headers and S/Steel exhaust!! I run the NA at 31psi on the road but don't 'track' it, while the NB8A runs 35psi both road & track

I know JBT runs them on his NC for both road & track, interesting if he does a post and let's us know what pressures he runs

As a matter of interest, during the duration of the first set on the NB they were NEVER rotated, always left on their original corners

[Hjt]

ku36 is a s spec tyre mate.

That 10 second difference would be mainly driver pushing his car, you should have asked for a lap around the circuit if you wanted to see a closer comparison. I hope these tyres instil more confidence in you to push the limits though

[Apu]

I did have a ride with Alex - it's a huge difference (and I didn't realise the 36s were S-spec tyres until I got them).

Not sure I will gain that much as I don't see myself being quite that aggressive, but definitely will drop below 1:20 since I did a PB of 1:22 on the KU31s.

[Guran]

KU36s are probably about a second quicker around Wakefield Park than KU31s. You should find you can corner a little faster with them. Great news! But be careful because when they do let go (even slicks let go eventually), you'll be going that little bit quicker, and the consequences could be a little more serious.

Also KU36s have less wet grip than KU31s so take extra care when driving on wet roads. Hint hint, Bryan!

[JBT]

KU 36 on the NC are very impressive. I run 31 psi cold for normal use and 33-34 psi cold for track. Charlie Brown thought they were very grippy when he drove my car at Wakefield Park on the Natmeet track day. As far as I'm concerned, the KU 36 grip and wear far better than Toyo R1R, Bridgestone RE 050A and the old Michelin Pilot Preceda...and cost about half the price Noise? What noise? The roof is down and the Bose volume is up. Then there's my tinnitus...

I have KU 31 on the BMW. They're run at 35 psi front and 41 psi rear cold (staggered wheels) - about half way between that recommended by BMW for normal and hi speed conditions. The grip levels on the road in the Bimmer are astonishing with these tyres but I haven't tried it on a track...yet. they seem quiet but how would I know

[Captain Scarlet]

What size KU36 could I fit on an NA6 please? I have 15 x 6.5 rims with 195/50 tyres.

CS

[Apu]

KU36s are probably about a second quicker around Wakefield Park than KU31s. You should find you can corner a little faster with them. Great news! But be careful because when they do let go (even slicks let go eventually), you'll be going that little bit quicker, and the consequences could be a little more serious.

Also KU36s have less wet grip than KU31s so take extra care when driving on wet roads. Hint hint, Bryan!

Judging by how hard Alex was going, I guess I could squeeze two seconds out (and he was 10sec faster on the day). The KU31s squiggle around quite easily and I'd just back off rather than hold throttle.

As for the wet...yup, that spin on the iceberg run is still fresh in my mind. I was on the 595s then though!

[Apu]

What size KU36 could I fit on an NA6 please? I have 15 x 6.5 rims with 195/50 tyres.

CS

I'm running 205/50/15s on mine, and we have the same sized wheels. Kumho recommend a max of 205 for our size.

[zero00]

Captain Scarlet

I have 205-50-15 on both, NA runs 15x6.5 Kings and NB runs 6UL '949' 15x7.5

When i think of it, my PB at Lakeside was done last October when the rears were almost 'shot' and still they didn't let go! They handled just as good as when they were new, and i would go so far as to say, even better!!

Agree with JBT, just turn the stereo up!! On the track you have NO IDEA of road noise!! All I do is watch the tacho, rear views and pray!! Actually, I can't make them squeal like you hear from other brands

[project.r.racing]

I agree with most things that have been said.
I would've never have got a set of 31s expecting majic on the track. They are clearly a street tyre. And anyone that has previously owned set, can tell you they will hum louder than the 36s when getting old.

The 36s are only marginly better than the 31s. Cannot say I've noticed a ride quality difference between the two. But always had coilovers since I started dealing with modified street/race cars.

Always been a little dissappointed with the tyre wall not being rigid/strong enough compared to other tyres. But that then is comparing them to R spec stuff.

In an ideal world, I love a Kumho to make a second version of KU36s that had 2 ply sidewalls and a sticky compound that gave wear rating or 100-140.

Then the 31s and 36s are both street tyres. One is a great allrounder, the other sacrifices wet grip for improved dry grip. I'd expenct 1-2 second lap improvements, where from a R spec you'd get 3-4 seconds.

[OurCognitiveSurplus]

What sort of tyre width are you running?

The 6UL comes from 15x7 to 15x10, but the KU36 and Federal 595rs-r only come in 205. If you got a 15x8 or wider, I can't find anything that would fit. Even the r888 only goes up to 235 (suits 15x7.5)

http://www.mx5centre.com.au/index.php?m ... Path=80_81
http://www.federaltyres.com.au/tyres/ul ... ce/595rs-r
http://www.racetire.com/products/toyo_r888.htm

I guess the point I'm making is that I run KU36. They're good, but only come in one size. What's the point of getting wider wheels if nothing fits?

[project.r.racing]

Cheapest light weight wheel+tyre options with street usable tyres would be these options:-

15x7 Enkei PF01 wheel w/ 205/50R15 Kumho KU36/Nitto NT01 ($1800 depending on USD vs AUD)
15x8 Enkei PF01 wheel w/ 225/45R15 Nitto NT01 ($2000 depending on USD vs AUD)