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GEOMETRY and TRACKDAY tyres

M

Mike58

PCGB Member
Member
Using a new guy ( to me) for geometry he is well recommended and I should know by Feb 09
My requirements are to lower the back a bit to achieve a level or sl. nose down profile <1.5cm fr/rr. with around 1- 1.5 neg camber.
I'll let you know how this goes and any difficulties encountered,

Phoned my Dunlop supplier today didn't seem to think that my recent D10Js were avail for the rear!!
They didn't follow this up with the email quote promised for other makes, so perhaps they don't want my business[:(]

SO,, what is available for trackdays on a 16'' rim, has anyone some good buys or recommendations/

I will consider 205/55 205/50 fronts
225/50 225/45 rear
245/45 245/40 ( if that exists)rear

I hear a rumour that Pirelli still have P Zero Cs for 16'' rims can anyone confirm that?

I am tempted to try the new Toyos or the Khumos, but I do want to give Richard a run for his money at Spa, so maybe I should just invest in pilot sport Cups and hope it stays dry?

C'mon people advice needed


By the way my Dulnops are still in good shapeish but the treads are full of melted rubber rendering them road illegal, what do you thinks of regrooving the treads to gain the 4-5 mm needed to drive back home after a good trackday, has anyone any experience of regrooving this sort of tyre? If so what did you use.

So many questions so little time.............


Would reallly appreciate feedback

apart from Richards Barum remould advice..[:D][:D]

PS I really want to try a Ducktail on the car anyone know of a D Tail for sale??
 
Mike

I'm on 15's so even less choice for Track tyres.

If you find any P Zero C's, please ask if they have 15's & email me.

If you can get Toyo R888's they should be good - at least "leagaleagleboy" was going well with them in his 968 @ Brands a few weekends ago & they are not a bad price.

You should be able to get D01J's via Parc Ferme amongst others, or you could try the Yoko A032R or A048 (new version).

If I could get them for 15's I would have a set of Dunlop Super Race, but I think 17" is the smallest they come in.

Hope that helps.
 
Had my first drive ( in anger ) after the set up.
Now I don't know if it was the greasy roads, the fact that it's been off road for 3 months or the susp mods but the car felt twichy.

V V twichy

arrived at work and the staff asked -- are you alright Doc.B?

Pulse was racing car felt super responsive but almost dangerous, steering v,light.

Later I trusted to use a lighter grip on the wheel and things improved a little, but the car felt like a wild animal on anything other than smooth tarmac.

Mmmmnn this road track compromise is a truism after all.

Got a deal on P-Zero Cs but expensive if you want 245/45/16
I got a ducktail but haven't fitted yet may not like the look.
 
Mike, was this drive with the P Zero-C's on the car? If it was then they will not be getting anywhere near the required temperature on road at this time of year. Could this explain the alarming handling?
 
No just normal road tyres.
I do think it was my unfamiliarity with the car + greasy roads but I will soon find out at Oulton on Sat 5 march.
 
Less of the old boy Melv, according to fat boy slim I am a tw@t, which i think is more suitable ( SRF thread Scotland ).
Camber should have been 1 deg fr, 1.5 rear.
I'll give it some more stick this week and show it who is boss, then i'll drive the car a bit.
 
Mike

I've got the P Zero C's on the car at the mo & similar camber angles to you. Normal road driving is fine, even though the tyres are not getting warm. See you at Oulton (snow permitting) & perhaps you can have a session in my car to compare.
 
OK Andy
My car is a white 3.2 Cab reg A9POR, there won't be too many of them about ( same with CSs)
RSs on the other hand-- common as muck[;)]

You going to the Chinese on Fri night?
 
Slightly late response but I thought it might be useful to add a little more info. Unfortunately 16 inch track tyres are becoming increasingly rare.

First, the PZeroCs are still available from Silverline and are on special from time to time. They are IMHO a good tyre but have been overtaken by others. The sidewalls just aren't that stiff so turn in is not stellar. However, apart from aquaplaning they are a pretty good rain tyre. Even with 4-5mm tread they only aquaplane at 100+mph.

My current favourites are Dunlops DO1Js which have very stiff sidewalls and loads of grip. I find them skittish in the wet but the large grooves offer good resistance to aquaplaning. I think a screwdriver would work well to clean the grooves of melted rubber. The tread pattern would make regrooving difficult. These only come in 205/50 and 225/45 for 16s so they are not ideal for 7/9x16 wheels. I use the 225/45 for fronts and something else on the rears - currently PZeroCs - so the turn-in is great and the rear fairly forgiving. BTW, the smallest SuperRace Dunlops are 17 inch.

The Michelin Cup Sports are probably great. I have driven on them but have not owned a set. On very light cars they don't seem to get enough heat to work to potential. Good wear and good in the wet if over inflated to open the grooves.

Yokohama, AO48Rs don't come in the right sizes for 16s but AO32R come in 225/50 and 245/45 IIRC. The 32s are old school and were never on the pace with other R tyres but they wear well. Also over priced from Demon Tweaks. Also very noisy like an offroad tyre. Still, a possibilty.

Toyo 888s look great but again no 245/45x16 is available. Toyo do not expect to add this size either. Same dilemma for the new Avon ZZR. If Toyo imported the RA1 it would be perfect but they will not - I asked them.

The budget option may be to try Colway Traxter. They come in any size that they can get matched carcasses for - usually Michelins - and are cheap at circa £35 each. I have a set in 205/225 for the road and wet days. They come with 7mm tread (shaved from 9mm). Unfortunately they have less grip than Cup Sports in the wet and less than any other R tyre I have used in the dry. Still, Jamie says to persevere and wear them down a bit and then they will perform better, which stands to reason. I have done a couple of dry sessions, a full day in the wet and maybe a thousand road miles and I can still see the marks where they were skimmed/shaved so the longevity bodes well if nothing else!

If anyone knows of any other options please let me know. Until then, I think I will stick to my thoroughly heat cycled DO1Js for the front and equally heat cycled PZeroCs for the rear. Maybe Cup Sports next only because they are available in close to my preferred sizes - 225/245. Lack of available R tyres is the one thing that may make me go to 17s - eventually.

Mike, I found 1deg front camber was fine on the road and even current 1.5 is ok. IMHO, your toe is more critical for the way it feels in terms of "pointiness".

RB
 
Richard, any experience of your Dunlops going off, mine are now fairly blue with some sunken areas ,mainly around the edges, the dealer i bought from says as soon as the blueness shows the grip levels drop dramaticaly.
I ran the dunlops around 2Bar hot, what press/temps do you use., and what about the P=ZeroC temps/press
 
mine go a little blue but don't really seem to go off too much at all.

I run them at hot pressures of about 33-34psi - so start at about 25-28psi depending on hot/cold track temps. Seems to be a sweet spot though I don't know what Dunlop recommend. Silverline say 31-33psi hot for PZeroCs IIRC.
 
To update an old thread.

I'm struggling to choose tyres for my recently acquired 16 x 7 & 9's.

Can only find 245x45/16 for the rear in Pilot Sport Cups, which when paired with either a 225x50/16 or a 205x55/16 are going to cost £673 a set delivered[:(] (Black Circles)

Formula R's - D01J's now in limited supply & therefore old stock.
DZ02G's in 205x55/16 + 225/45/16 are £561 a set delivered (Mr Tyre)

Toyo 888's in the same sizes as the Dunlops £468 (Black Circles) which look like the best bet, but has anybody tried them on a similar car?

Feedback appreciated.
 
Andy,

Your sizes won't work - 205/55 is too tall to work with 225/45 rears and the 9s are too wide for a 225/45. You can get away with 205/55 or 205/50 and 225/50 on 7/9x16 but you are leaving lots of rubber on the table. My 245s are massive compared to the 225s.

My next set will be Kumhos which are cheaper than the MPSCs and which are preferred by a lot of the hillclimb boys. These ones:

Kumho_V70A.jpg


They get rave reviews in the US, second only to the Toyo RA1s.

The problem you will have is getting the 225/50 to fit at the front without rubbing. My last set rubbed despite 1.8 degrees camber and rolled arches and that was before I had to add a 5mm bearing spacer for the 964/951 brakes. My 225/45s barely fit now. Maybe you will be lucky and find they fit. The left front will be the tightest fit.

I am going to run 2.3 degrees camber to get around the clearance issues which suits me fine as the car does few road miles, but this won't work for everyone as you need different top strut mounts to get this much camber. The other option is a 205/55 MPSC, which is particularly wide for a 205 but should fit a little easier. Should work fine with 245/45 rears.

RB
 
One other thought - run 225/45s from one brand and 245/45 from another. Which is what I have done for the last two years - DO1Js front and PZeroCs rear. Works well as the fronts have lots of bite from a very stiff sidewall and the rears are a little forgiving but give up little in outright grip. The shorter front tyre gets you a little extra clearance up front.
 
The plot thickens.

I currently have Kuhmo Ecsta MX's on the car in 205x55/16 & 225x50/16.
Not tried them on track but Raymond Boyd who sold me the wheels has once (he bought the tyres for wet / cold whether use) & said they were pretty good. He had them on a 1972 911 - no rubbing & so far no rubbing for me after about 300 miles road use - I'm running 2deg neg camber on the front.
I believe a 205x55/16 has a rolling radius of 316mm (as does a 225x50/16) where a 225x45/16 has 313mm - can this small difference have an adverse impact?
I would like a 245 rear, but I'm just not keen to mix makes.

Thanks for the comments so far - need to think on this a bit further.
 
You can use any of the following as rolling circumference is close enough not to matter: 205/55, 225/50, 245/45. In addition, using a shorter front tyre like a 205/50 or 225/45 is fine and will sharpen turn-in and give you more clearance.

The Kumho MX is one of the better non-r tyres for track use because it has nice big tread blocks. It is favoured in some US autocross classes where they cannot use r-compounds. It will work just fine, but will be a long way behind a true r-compound. In rough terms, I think the increase in grip from r-compounds is like going up at least a tyre size - say the difference between 205/225 and 225/245.

Mike, the Toyos seem great,but the sizes just don't work for us unless the sizes have changed since I talked to them in 05. I have picked a few brains and the only tyres that work in terms of possible sizes are Yoko AO32R, MPSCs and Kumho 710s. I discount the Yokos as they were never very good and they cost as much as MPSCs. If the sizes are available in something else, I would love to know.
 
I've just done a similar trawl for 16" R tyres at 205/55 and 225/50. It is really surprising how little choice there is in terms of getting a matched set.

I came up with the same options as Richard with Toyo R888, MPSC, PPZeroC and Yoko's. Finally settled for the Toyo R888 as these are avialable at around £200 per car set less than the other options.

I think its a bit of a risk as most recommendations seem to be for the MPSC but at the price of £460 a set its worth go. I'm hoping for a significant improvement over my S02's which are now relegated to a wet status after some ten track days!

Of the suppliers I talked to they semed to have very little feedback on the R888. So the asumption is, no news is good news.

For info Demon Tweeks were doing a some good prices on Kumho V70 but wrong sizes for me!

Bruce
83 sc
 
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