Track rubber for standard 18" wheel - Need rim width

[moonigan]

I'm just looking at sourcing some track rubber for my 18" rims but cant decide on which to buy and in what size. Currently looking at Pilot Sport Cup, 888's and Kumho V70. I've heard some good reports about the Kumho's which is good because they are considerably cheaper than Cup's and 888's. However I cant decide what size to get. With the cups and 888s I was going to go 235/40/18 & 265/35/18 however Kumho only have the following options.

225/40/18
245/35/18
265/35/18

The obvious choice is to go 225 front and 265 rear but I was thinking that the 245 at the front might give better grip (dont really know to be honest). Does anyone have any thoughts/suggestions ? I also need to know what the rim width is for the standard 18" wheel to make sure the Kumho will fit OK.

Cheers
P

 

[mmm-five]

I'd stick to the 225 and 265 combo, otherwise you'll end up inducucing more oversteer as the front will have more grip (not necessarily better) relative to the back.

A 265 will be fine on a standard rear rim, as will a 225 or 245 on a front rim.

I really like the Cups, but I couldn't justify the price, and the R888s have shot up in price over the last 6 months or so. Camskill used to be the best place to get them though. The Hankook RS2 are similar to the Kumhos, and Yoko A048R are similar to the R888s (performance-wise).

 

[moonigan]

I'd stick to the 225 and 265 combo, otherwise you'll end up inducucing more oversteer as the front will have more grip (not necessarily better) relative to the back.

A 265 will be fine on a standard rear rim, as will a 225 or 245 on a front rim.

I really like the Cups, but I couldn't justify the price, and the R888s have shot up in price over the last 6 months or so. Camskill used to be the best place to get them though. The Hankook RS2 are similar to the Kumhos, and Yoko A048R are similar to the R888s (performance-wise).

Cheers for the info. I did think about the A048R but I had heard they didnt suit heavy cars like the Z4 and were much better suited to lightweight cars. I'd be interested in hearing your experience of different track rubber. I'm not looking at doing lots of days (maybe one a month during the summer months) so I'm more interested in durability than outright performance.

P

 

[mmm-five]

I haven't used any track rubber on the Z4 as I've more or less stopped doing track days due to the amount of money I was spending

However the last car I did a good number of track days in was a 1700kg e34 M5 and that would eat tyres. The best compromise I came up with was having two sets of whee's & tyres and I'd do a couple of laps first thing on the road tyres and if it was damp & squirmy then I'd stay on them, otherwise I'd head back to the paddock/pits and put the track rubber on.

I started using Michelin Pilot Cups in 18", then went down a wheel size to 17" and started using part worns from some of the race series, including Pirelli P-Zero Corsa (from the Porsche Carrera Cup cars) and had about 17 of those for £50 (about 8 years ago though). I also got my hands on some tarmac rally tyres from a Subaru WRC owner who only used them for setting the car up - Silverstone S575/S585 IIRC, and they lasted about 5 track days - although they're not road legal (there's a new tyre called the FTZ type RR which is, but it's not available in 18").

The Pilot Cups and the P-Zero Corsa/C tyres are great for our cars, but they're very expensive. The Toyos are great too, but they're taking the piss with their current pricing. Yoko now do a wide ramge of track rubber in different compounds for heavier cars so there must be something available. If you get something that's too hard wearing then it's going to slide all over the circuit and will be useless on the road, but if you get something too soft it'll just melt after a couple of laps and you'll have nothing to drive home on.

The larger the wheel, the less choice you have and the more expensive it becomes.

The tyres you end up using will, to a large degree, be down to personal handling/grip preference. Some people like a tyre to grip & grip and then let go suddenly, whereas I like the ability to slide the car through fast corners so prefer a tyre that breaks away very gradually.

Stickier tyres will also increase the rate at which other components wear. e.g. you'll be going faster so brakes will fade/wear faster, suspension components will wear at twice their normal rate, etc.

 

[mmm-five]

BTW, this reminded me of an incident I had as a passenger in a friend's e34 M5, just after he bought some Silverstone tarmac rally tyres.

There is such a thing as too much grip
[youtube]M2ZbmQVTjHw[/youtube]

 

[moonigan]

Well. I got the Kumhos and had them fitted to my 18" rims over the weekend. The combination of lower profile and much stiffer sidewalls make the ride a pretty hard but the turn in and feel is amazing compared to the crappy contis that came of the car. I'm going to Oulton next week so hopefully it will stay dry and I will get a chance to try them in anger.