Trackday tyre help please

[tvrbob]

I'm currently running worn out Toyo T1-S's on a spare set of rims on my Chimaera. After fitting adjustable dampers and stiffer springs and better alignment I now find the car is more squirmy than usual at the rear under hard braking / change down. The car was OK prior to the suspension updates but now I can carry more speed through the corners and the rears have become the new weak spot.

I want to put trackday rubber on the rear rims and would like to keep the original size, 245/45-16. All I can find in that size are....

Yokohama A032 R
Kumho V70A
Hankook RS2 Z 212
Pirelli PZERO ASIM

or

Toyo R888's and Avon ZZR at 225/50-16 (same overall dia but 20mm narrower)

Does anyone have experience of the first 4 types? I know Toyo's and Avon's are used by many TVR track cars but that means I'd need to run a narrower tyre.

[FezzaO]

I have lots of experience with Kumho V70A and a little with the Toyo R888

The Kumho is fantastic tyre. I use the medium compound (K6A) which is very soft so short lived but even the hard compound 9K9A) is very very grippy.

I have not used both tyres on the same car so cannot compare

[tvrbob]

FezzaO said:

I have lots of experience with Kumho V70A and a little with the Toyo R888

On what car? Your profile doesn't say

[Jubal]

I ran V70As on an Impreza STI. They were hugely grippy but the outside pair gave up their best in one day at Oulton. That said, even though they were directional I swapped them around on the advice of Kumho and did two or three more trackdays with them with no loss of performance. The guy who bought my car did the same and has only just retired them when they wore down to the steel Expensive but good is my opinion.

[FezzaO]

tvrbob said:

FezzaO said:

I have lots of experience with Kumho V70A and a little with the Toyo R888

On what car? Your profile doesn't say

I use the Kumho on my track wheels on my BMW M3 E36 (modified for track)
I have fitted R888 on a Ferrari 575 but very recently so cannot say much about them so far.

[jon-]

I've a few track tyre reviews here: http://www.tyrereviews.co.uk/Type/Track-and-Compet... (if anyone feels like helping out and adding more that'd be great)

Both the Yokos are meant to be great, but expensive. The R888s are cheap and cheerful, seem to have a problem with overheating. The V70as might be worth a look, IIRC they won the bild track tyre test.

[wilbo]

R888's

[Shropshiremike]

jon- said:

Both the Yokos are meant to be great, but expensive. The R888s are cheap and cheerful, seem to have a problem with overheating. The V70as might be worth a look, IIRC they won the bild track tyre test.

Yes the Kumhos did pretty well in that one - on a 3-series.
Spoke to a guy using them on a Sierra at Castle Combe the other weekend and he really rated them - as good as 888s in his opinion

[Cavey]

I had a ride in Iguana's E30 325i (track prep'd) at Colerne airfield day the other month. He was running Toyo 888s and the traction in the wet was very, very good. I was expecting big drifts on the quicker bends, but it just hung on. Which was nice.

[griffdude]

Used to use Yoko 32Rs with Chim Imolas on my Griff, Swapped to Dunlop DZ02J with 225 rear/205 front......Very good, less prone to overheating on the 'diamond' on the Yoko tread.
ps you might want to think about oil surge prevention.


did I read that you only wanted to put the trackday rubber on the rears?????

Edited by griffdude on Wednesday 18th July 10:12

Edited by griffdude on Wednesday 18th July 10:12

[tvrbob]

griffdude said:

did I read that you only wanted to put the trackday rubber on the rears?????

Probably all round. The reason I'm asking about rears is because with my current set-up the rears are the weak point. The brakes are ~85% to the front which is great because it allows me to permit some engine braking which in turn helps me to be in the power band on turn in. What I found was that my suspension and alignment changes increased the effect of engine braking such that the back end now fish-tails at the limit. This may be due to the rear damper return being set too slow, i.e. the rears skip on the track surface bouncing the car up and the dampers aren't quick enough to get the rubber back on the road. I like the rear very stiff so I thought sticky rubber would help.

griffdude said:

ps you might want to think about oil surge prevention.

How is this done? Is there a baffled sump that I could buy?

[shaunsmith]

The best track tyre bar none is Pirelli P Zero Corsa as they have outrageous grip plus 15 laps around most English tracks without running off including 3 laps around the Ring continuous. For grip & safety nothing comes close, however they are expensive. 'You dont climb mountains in sandshoes'

[griffdude]

Go for matched treads all round if as all poss, it'll make for better balance all round..... Much easier to drive too.

griffdude said:

ps you might want to think about oil surge prevention.

How is this done? Is there a baffled sump that I could buy?

John Eales produces one.

[GarryGSXR]

Ok then ?

[wee_skids]

Bob, I can't quite understand you description. You've a lot of front bias on the brakes so probably a lot of dive on the front when braking hard? But then I get lost in regard to your engine braking? I always consider engine braking as what happens when you leave the clutch in but are not accelerating-ie braking with clutch in or just lifting off the throttle. What do you mean by this, and what alignment was altered? Is there any gear downchnage involved in this process?
I think looking at damper rebound levels is perhaps going to granular too soon, sounds like there is larger scale problem than return rates.
Just out of interest, what cold presure do you run these tyres at?

Tony

edit - bugger it's an old thread that been reanimated.

Edited by wee_skids on Tuesday 14th August 18:10

[tvrbob]

wee_skids said:

But then I get lost in regard to your engine braking?

In the braking zone but closing on the corner I change down ready for the corner. Throttle on clutch down so the engine and road speed are balanced before releasing the clutch then throttle off. There is the expected increase in rear wheel braking due to lower gear ratio and throttle off. Since I stiffened the rear dampers there has been a change in the cars handling during this phase. All is well at first, engine braking due to change down is stable but any undulation or bump in the road and the rears lose traction.

wee_skids said:

what alignment was altered?

Basically I run on Derek's (Absolutelyshocks) alignment but set the front toe to zero when on track. This improves turn-in

wee_skids said:

what cold presure do you run these tyres at?

I run almost bald Toyo T1-S's at 26/29 on track. That's simply trial and error. Being less rigid on the walls than the SO2pp they need to be a couple of psi harder even on the road, I simply added pressure on track until they stopped tucking under when cornering.

Edited by tvrbob on Tuesday 14th August 18:51