running slicks with 18's ????

[_Nathan_]

Aps fit under 18s fine, assume you have am suspension already?

[alexk]

I am running M3 E46 18" with Dunlop slicks.
All rims are 9J and I have wider rear slicks (rears are 240 and fronts 210).
They can fit in the AP brakes (and I have the CP5555 calipers with 18mm thick pads // my front rims are 9J).

I run them with OEM suspension.
I am VERY HAPPY with them. The grip is phenomenal.
I don't see any problem in the car.

[shimmy]

Why are you running slicks

Speed

Cost

???

[alexk]

Originally Posted by shimmy

Why are you running slicks

Speed

Cost

???

In the bike I used to run slicks all the time (road use too).
As you know shimmy (you helped with the transfer ) I got the slicks for the car in a good deal.
The traction is so much better compared with the cups so why not to use them ?

[daniel]

Or you can buy 4 x rear 18" bmw wheels, as per AlexK, for around 200. There are other sticky options to consider that are a lot cheaper than cups and maybe safer than slicks.

Originally Posted by shepp80

Thanks for the reply! definitely answered my question

The grip is really good, but the issue is the cost of cups all the time.

I know someone who bought ten sets of slicks, used, with loads of grip for £300 off ebay. they were 18's, and i think were also Dunlop

£1200 for one set of cups seems a little excessive to me. ive just worn mine, i think a change to slicks would be a good idea.

You can buy a brand new set of 18'' super lightweight rota wheels for £800

[alexk]

Originally Posted by daniel

Or you can buy 4 x rear 18" bmw wheels, as per AlexK, for around 200. There are other sticky options to consider that are a lot cheaper than cups and maybe safer than slicks.

Yeap you can get good deals for 18" bmw wheels.
I am not sure why you say that slicks are unsafe ?
Have you tried slicks ?

[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.

[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]

Originally Posted by 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.

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.

[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.