running slicks with 18's ????

[alexk]

I didn't think I was having a go at anyone? However I wasn't really referring to pick up, I was thinking more of the tyre wear around that, I wasn't referring to your car as anything other than an example, sorry if you took that as negative, it was not intended that way. My point was that running slicks works up to a point and that it was not completely without some risk (which is negated by checking the car) that's all but it was an option when wanting to have more fun on track.

As for laptimes and comparing to other cars on track, well that's not something I do, for a start 90% of a lap time is the driver, always has, always will so I never compare car to car on track as its moot. Unless of course it's racing and that is more than times, its who finishes ahead, not an attitude I think would go down well on a track day!

Running slicks does add fun, but if the desire is to be faster then there are other ways of doing it, thats not to say running slicks is wrong, far from it, just one option when looking for faster times. Thats all I was trying to get across.

No John, I didn't say that you were negative or having a go (sorry if my tone indicated something like this).
Quite the contrary, your input is very good :thumbs:
And of course you have far more experience than me :beer:

Shimmy, all good mate.
John is making very valid points. I don't disagree that fresh cups could make faster laps (you mentioned that curly has tried them extensively).
However, give them a try at some point :thumbs:

[titan]

As some of you know, I've a mentalist race-prepped evo. That runs 285 profile DZ03 rubber at each corner.

I don't run slicks. And I'll tell you why by way of an example.

When I was at snetterton last in the evo a fellow northlooper was out in a GT3 on cups. He was going round Corham as fast as his level of grip would allow. He came and saw me later to tell me that I went around the outside of him like he wasn't trying.

Stick slicks on and you'll go faster still.

And therein lies the issue. When you do come off you'll be doing god-only-knows how much extra speed than you were before. Fine if its a track with a load of run off (but I still reckon you'll end up in the tyres) but I enjoy trackdays at the ring. Not quite the run-off area you need ;-)

The other issue is that these cars weren't designed to run with that level of grip. Wheel bearings, strut towers, suspension, even the chassis will be asked to do stuff it wasn't designed for. I haven't had the experience of a wheel bearing breaking mid-corner but I can't see it being a cheap one.

My last trackday was the first trackday I've done in the CSL, sitting on smaller-profile-than-specified contis. UB was there with his R888. And he was tramping round far faster than I with barely a glimmer from his DSC light. Me? I had the DSC off and was having the time of my life. Yes I spun on one attempt to set a new drift record ;-) , but at the speeds I was doing, it was a non-issue.

I want to learn how to drive and control a RWD car properly and I don't see that happening with slicks. I'd be back where I was with the evo, tramping around but ultimately not learning much.

Ultimately we all have different reasons for trackdays so I'm not judging. If you want to blast around (and timing suggests you do!) then go for it.

I did just buy a set of cups for the CSL 19" so it sounds a bit hypocritcal, but I'm waiting on some TD 18" where I'll run Federals or something. The cups were just to have a set of CSL wheels with the specified tyres on them :-)

[Thorney]

I didn't think I was having a go at anyone? However I wasn't really referring to pick up, I was thinking more of the tyre wear around that, I wasn't referring to your car as anything other than an example, sorry if you took that as negative, it was not intended that way. My point was that running slicks works up to a point and that it was not completely without some risk (which is negated by checking the car) that's all but it was an option when wanting to have more fun on track.

As for laptimes and comparing to other cars on track, well that's not something I do, for a start 90% of a lap time is the driver, always has, always will so I never compare car to car on track as its moot. Unless of course it's racing and that is more than times, its who finishes ahead, not an attitude I think would go down well on a track day!

Running slicks does add fun, but if the desire is to be faster then there are other ways of doing it, thats not to say running slicks is wrong, far from it, just one option when looking for faster times. Thats all I was trying to get across.

[DuncanR]

back to your question!

most 18 inch rims should be fine with APs, just check you have Cp5575 front kit and not CP5555 which are slightly bigger callipers,

Alexk is using CP5555 :clown:

[shimmy]

Hi,

Im looking at dropping down a rim size so i can run slicks on my CSL.

Been looking into it and im worried that my AP brakes fitted on the front will hit the inner rim.

Does anyone know whether they will? as i don't want to buy find out the hard way!

Also has anyone run any slicks, what are they like etc...any recommendations

Thanks

back to your question!

most 18 inch rims should be fine with APs, just check you have Cp5575 front kit and not CP5555 which are slightly bigger callipers, CP5575 was specialy modified to fit under OEM 18 M3 inch rims.

[shimmy]

You get the slicks mate ... and I will supply the car !! seeemple !!!!:thumbs:

Lets make it at Bedford tho shall us ? .. just in case !!

gOOD IDEA, MAYBE WE SHOULD DO IT FOR THE CSL Challenge day at Bedford next spring

:thumbs:

[DuncanR]

id love to give slicks a go tbh, and maybe next year i might break my rule and run some somewhere or i may have to just wait fior a race drive:smokin:

You get the slicks mate ... and I will supply the car !! seeemple !!!!:thumbs:

Lets make it at Bedford tho shall us ? .. just in case !!

[shimmy]

Alex, i dont think John was having a go!

I think the point being if it is speed you are after with slicks then where slicks get alot of their speed from is running with firm springs, rigid caged car, and the right geo.

I spent alot of time with Dontdobends who was running his m3 race car and previously his CSL on used slicks and i think Johns conclusion was that on a non race car (or non set up race car) used slicks were more or less comparable to new Cups for outright pace, maybe with a slight advantage with slicks if you have a/m suspension

id love to give slicks a go tbh, and maybe next year i might break my rule and run some somewhere or i may have to just wait fior a race drive:smokin:

[alexk]

1. Set up, to use a slick on an M3 you need min 4 degrees of camber to make full use of them, otherwise you will just wear them out quicker and compromise the handling rpbably where Shimmy gets the comment that they are no faster than cups, he's right, with 2.5 degrees front camber a front slick will overheat in 2 Laps, get greasy and slow you down). If you look at Alex picture you can see the tyre pick up on the inside edge of the tyre - too little camber.
2. Wear on the car, slicks have 40% more lateral grip than road tyres, that stress goes through the chassis so bushes, suspension mounts will all wear more, this includes the chassis, there's no evidence that slicks will damage the chassis but I would certainly be checking subframe mounts etc more often if I ran them on a road car.

JT thanks for the input as a start.
I think most points are correct, however I want to comment on some things.

The pick up of rubber in my slicks in the photo is from a cool down lap in Spa, full right where is was full of rubber from other cars and I picked everything inside (because my car has camber so in the straight line the inner part of the tyre is applying more pressure on the tarmac).
The extra camber has to do with the driving style + speed.
If your driving style is different (and possibly speed) you might not benefit from excessive camber.
If you see the condition of my cup tyres after 18k road kilometers, 22 laps in Nordschleife, 2 track days in France and drifting in CH, GR and the racetrack, you won't believe it !
I can take some pictures and there you can see that my 'stock' camber (max setting btw) is fine. I don't have uneven tyre wear.
So in a similar way my slicks don't have uneven wear (when I corner the tyre it has a 90 degree angle) so I that case I am not sure how extra camber would help me.

You could say that I am captain slow but I don't think so.
In the French track I could lap 1.32 in my slicks in the wet (backing off 2 fast corners not to have an exit with 180km/h). The 1.29 is feasible AFAIC.
Doing 30 minute sessions I didn't see any degradation of grip nor my tyres became greasy.
What I noticed is that my brakes became EXTREMELY hot, which is justified by the extra grip of the slicks.
And this is a track that an aftermarket suspension would make a difference because it has a lot of tight corners.
It was also interesting to see that a Nissan GTR tuned, with semi-slicks and wheels and suspension and gay-4-wheel-drive wasn't faster than me in the corners (I will say again the tarmac was wet).
I can also quote some other laptimes in the same track in the DRY.
M coupe with michelin slicks, racing suspension, cage, exhausts etc. 1.35
997 GT3 RS with semi-slicks 1.31

Would a CSL with roll-cage, suspension, geo on slicks would be much faster than me ?
100% YES !
But I am a hobbyist so I am happy with what I achieve while having fun and not taking it too seriously (I respect that others see it differently though).

[DuncanR]

Thx for that input JT, as you know, Im looking to "try" a set out ... just for the hell of it really ... I also wouldnt be doing it without a cage though, as per Shims statement. All i need is some kindly person to let me have a part worn set to complete the exercise whilst I still have a set of empty 18"TD rims to bang them on !:whistle:... good point about the BTCC and the possibility of more availability.

[Thorney]

Sorry, can't edit post on iPad easily, forgot to mention on set up it also depends on spring rates, OEM springs will be too soft so the car will roll more doling the car onto the outside of the tyres, this heats them up, drops their grip and wears them out.

Also be wary about buying part worns, most people have no idea how to look at a slick to determine its life, there are wear indicators but these are only indicative, most slicks lose about 30% of their grip after 5 heat cycles.

That said, I've got about 10 sets of part worns for CSL cup cars that happy to sell for £100 a set

[Thorney]

Funnily enough I was talking to a guy on Saturday at Bedford about slicks on his M3 so may as well repeat the advice here.

Identify the reason why you want slicks, is it pace, fun, cost or all of it. There are positives and downsides though.

Positives
1. Fun, slicks are fun, more fun and lateral grip than any cup or cut road tyre.
2. Cost, part worns are relatively cheap and available (this will likely get better as BTCC move to 18" rims)
3. Saves wear on normal road tyres from track work
4.18" rims handle better in track

Downsides
1. Set up, to use a slick on an M3 you need min 4 degrees of camber to make full use of them, otherwise you will just wear them out quicker and compromise the handling rpbably where Shimmy gets the comment that they are no faster than cups, he's right, with 2.5 degrees front camber a front slick will overheat in 2 Laps, get greasy and slow you down). If you look at Alex picture you can see the tyre pick up on the inside edge of the tyre - too little camber.
2. Wear on the car, slicks have 40% more lateral grip than road tyres, that stress goes through the chassis so bushes, suspension mounts will all wear more, this includes the chassis, there's no evidence that slicks will damage the chassis but I would certainly be checking subframe mounts etc more often if I ran them on a road car.

There's no right or wrong on using them, simply personal choice of how to get the best out of your car on track, however what slicks are doing is offering more tyre grip rather than mechanical grip that things like suspension etc offer so compare a car with decent suspension on cups with a car on stock suspension on slicks I'd be interested to see which was quicker.

[shimmy]

8 full day trackdays for a set of cups isn't it a bit optimistic ?
I don't have the experience that you have shimmy (having only bought 2 set of cups up to now) but I find it a bit difficult.

Some colleagues were explaining me that they are supporting slicks+cage for safety reason, but personally I am not getting paid to race my roadcar, I am just a hobbyist having fun.

I think if you run slicks for cost savings then that makes sense as 4-6 TD for Cups is what I used to do. Better geo and understanding of pressure and temperature effects helps you to maximise this, stiff coilovers helps again and square set up allows an extra 2 by swapping front and rear Tyres. My 18 inch Cups did the 8 2010 trackdays for me and are no longer road legal but gave not worn to canvas anywhere yet so could still be used.

[alexk]

8 full day trackdays for a set of cups isn't it a bit optimistic ?
I don't have the experience that you have shimmy (having only bought 2 set of cups up to now) but I find it a bit difficult.

Some colleagues were explaining me that they are supporting slicks+cage for safety reason, but personally I am not getting paid to race my roadcar, I am just a hobbyist having fun.

[shimmy]

My take on slicks are like this.

Cheap worn used slicks are good value but probably not any quicker than new Cups. New Cups will on a good set up probably last around 5-6 proper trackdays so cost say £200 per trackday, without discount. Used worm slicks will probably run 2-3 trackdays max be costing say £100-£120 a track day

My 18 inch Cups cost me closer to £800 and Kuhmo are similar and on square set up will likely last 8 trackdays and cost around £100 per TD.

You can't run slicks on road so you have to lump around 4 wheels to every trackday which is a real faff. You can't run Geo for slicks and road at the same time so you'll never get the best out if slicks on a road car.

I've always said thatci wouldn't run slicks without cage for many reasons.