sticky tyres

[Tony]

Delighted with the performance of the Avons on the 911E but I'm looking for something a bit lower and stickier for the odd sprint and hillclimb. Car is now 1000kg and I've a set of 7x15 cookie cutters to mount them on - but, before I go out and buy a set of 205./50x15 soft Kumho V 70a's are there any good alternatives?

Tony

[MrD]

Yokohama A048 - soft compound for Sprints and Hillclimbs

Martin

[911hillclimber]

I've been through 3 sets of those Kumhos, two sets on my hillclimb/road 911 on 7" Cookies.

I truly doubt you will better a set of V70's in 'soft'

(that are road legal)

[redrobin911]

Hi - I used to do sprints and hillclimbs in my 911 rs rep here in NI - the biggest problem with all tyres is getting heat into them to make them work, I could suggest the softer compound in the Avon (A30) would be a way to go, the Yokohama AO48 is also a great tyre as is the Michelin pilot cup sport (pricy though) - I never used the Kumhos so can't comment on them but did see them being used in racing and seemed good. Problem is going to be what tyres you're allowed to run i.e. List 1a or list 1b in the MSA regs then finding a tyre that will fit your rims - this will narrow your choice quickly. But the trick is really to get heat in the tyres - spinning up the rears is the best known method to heat them but hard on drive shafts/diff/transmission - playing around with toe settings can hep with the front esp (also helps the rears)but will make the car twitchy for road use. If you can get to one of the PCGB speed events have a look and see what tyres they use and have a look at wheel set up.

[Tony]

Thanks guys,most of the PCGB competitors use Kumhos - in a range of compounds, sounds like that's the way to go. I just wondered what the current alternatives were and in particular if there was anything new. The Yoko's seem to be a harder compound, don't think I can get the Avons in a 50 series and not sure if the softer Toyo's are available in the size anymore.

Tony

[911hillclimber]

Really, it is very hard to get a clean answer to this question because we all have a different feel for things, and I guess, a good day on a hill = tyres are brilliant, a bad day = tyres are naff..

The Kumho's are List 1 B, any compound.

I've tried no tyre warm-up and flat out spin the lot up and the times are not that different because my skills/ driving the whole hill can negate the 10th you gain in the 64 foot dash.

My 911 above is a typical start, lots of deep traction (2.1 /64foot). The car has 3 litre turbo rear bars and custom dampers to suit yet squats quite a lot.
Despite shallow tread grooves, the Kumho's are really good (imho on a good day...) in the wet.

I very nearly got FTD in my Impreza on Kumho's at Loton a few years back in truly wet conditions. Pipped by an OMS on wet slicks.

One of my rare good days!

As an outside bet, the re-vamped Avon CR28 sport could be a good bet.
Lots of us ran them in road-going and they were quite good (we all agreed in the class)

I think the compound has been improved, bet ask Avon or BMTR.

[Boydyrs]

I have various sets of good used Yoko AO48, 205&225/50/15.
Willing to sell sets at reduced rate if it helps?
Boydyrs

[Uk911]

Have a look at the DMACK website, tyres used in rallying 1b approved and from Carlisle, good feedback from people I have spoke to about them, and available in 15 size..Mark..

[rhd racer]

Hi Tony

You are correct - we all use Kumhos in the Speed Championship. Nothing gets close to be honest, having worked through the P-Zeros and Yoko options through the years. I use soft compound all round on the 914, because I am not as hard on the rear as my 911 co-competitors. Some of them chose a medium rear and a soft front, or soft / super soft. my sizes on 7s and 8s are 205 & 225/50 x 15.

However, test days on circuits are a no-no, by the 3rd lap at Anglesea mine turned to marsh mallow and I wrecked two brand new rears! (I was having fun and knew they were close to the limit, but wanted to do one more lap!). If you are only doing hills, I would go for the softer end, you will not look back, they are awesome tyres. They last fairly well on the road in the scheme of things and whilst they don't displace much water in the wet they are soft enough to just about hang on.

HTH
Wayne

[911hillclimber]

Amen to that, Soft all round.

[Northy]

Can you run R888? - Most track day folk love them.

I've seen some stats somewhere (perhaps Impact Bumpers) on compounds and wear rates - the 888s came out best, if I remember correctly.

[911hillclimber]

The difference between Track day and hillclimb tyres I think are like day and night.

Track tyres have to be far more wear resistant and resistant to heat build-up and heat cycles.

With a hill climb the runs can be as short (in a 911) as 31 secs or as long as 60 seconds.

The Kumho V70 soft and super soft are particularly suitable but you can also drive on them on the road to events as I did (on softs) for several years, hence getting through 3 sets.

A full set on my hot Impreza lasted 4000 road miles. Their wear rating iirc is about 50. A road tyre is about 200+.
On a 911 the rears perish first and I squeezed about 6K miles from them.

They turn a 'dragonfly' purple when they have had enough, and need changing.

For track use (repeated circuits) their Hard grade is good, BMW used it as the control tyre a few years ago.

You do need to look-out for heavy road rain conditions at speed, just as you did if you had a fancy spec BMW M3 Coupe.

I moved to slicks from Kumho and at first found it hard to get better times from the car (Impreza) until one meeting at Loton, and it all gelled.

Took 2 seconds off my hill personal best and more later. Grip was quite breathtaking of course.

Their wear rate is 'Zero'....

Not all tyres carry a wear rating on the side walls, but as a rule of thumb, the lower the wear rate the stickier the tyre, but i doubt this subject is that simple.

[dragonfly]

Can you run R888? - Most track day folk love them.

I've seen some stats somewhere (perhaps Impact Bumpers) on compounds and wear rates - the 888s came out best, if I remember correctly.

I've got Kumho V70a for trackdays after talking to a chap who sprints a 911. He reckoned there was virtually nothing to choose between 888 and V70a having used both, and I decided the greater tread of the Kumho might be better on wet roads so chose those. I've got medium compound front and hard rear to try to even out the wear.
The consistency on track is great and they generate a lot of grip, but I reckon the early 911 chaps on crossplies are having more fun.

[rhd racer]

There is also the factor that the V70s are cheaper too - and quite considerably!

[wadsworthi]

The Kumho V70a is a fantastic tyre for Hillclimbs and I am sure you will not be disappointed with the performance.
I probably have some slightly warn 205/50 softs in the shed if you want to try them before you buy a set, they are a couple of years old I believe.