I'm going to start using full slick tyres in the near future. Basically I have narrowed it down to Michelin, Dunlop and Pirelli. Has anyone used these and what are your thoughts on them?

BTW I mean circuit slicks not for drags.

 

I've run Goodyear sportscar cantilevered slicks in SCCA racing for many years. They are the next level of grip from R-compounds (although R-compounds now come quite close) and are for racetrack use only. When they are hot, those suckas have incredible traction!

Drawbacks include cost and number of heat cycles before the tires lose grip. Keep in mind that the fastest laps in a set of slicks are always within the first four-to-seven lap heat cycle. Be absolutely certain to ask about how to put the initial heat cycle on, as this has a HUGE effect on how much longevity you'll get out of them. I also assume you're trailering your Z to the track for maximum use of the tires? Cannot offer any opinions on any of the three brand slicks you mention (since I couldn't afford them here in the States).

David Muramoto
Senior Editor
Nissan Sport Magazine

 

Thanks David. Yeah I've tried various R-Compounds (Bridgestone RE55, Toyo R888, Dunlop DZ02G) but I'm just looking for the next stage in grip levels.

I'll try and look up those Goodyears and see if they're available here.

 

Is this for racing, or just track days?

Slicks like you're talking about simply aren't cost effective for DE use... you tend to be on track so much longer in a DE/lapping evironment than you do for racing that the high cost and low life expectancy don't balance with the increased grip levels.

But hey... if you've got the money for two sets of tires for each event (to get the most out of them) then go for it!

All the r-comps you mention are still treaded R-comps... why not try some not-so-treaded R-comps like the Hoosier R6?

http://www.tirerack.com/tires/tires....r&tireModel=R6

Thats the trick set up around here when stepping up from treaded R-comps

 

Why bother? Unless you're competing for whatever series - it's just not worth it.

 

We have used Kumho for years. the current 710 tire is great and comes back over and over from hard use. The first use is the best for lap times of course but the drop off for the next many times isnt that much. If you want some used Kumho's to try we sell our take-offs for usually $300 a set plus shipping. We might even have a set of unused from the end of last year. I also think we have two sets of tires we used for qualifying. Those only have 4 to 5 laps on them. All our tires are for 18" Wheels. Email me your interest and I will forward them to my son. Tires are located in Arlington, Va.

 

Sorry, I didnt see that you live in Ostralia. I think Kumho is a force down there too as i've seen their banners at the Touring Car races that were recently shown on Speedtv

 

Merlot sending you a PM

 

Well I'm not involved in Nose-to-tail racing, just timed supersprints but would like increased grip nevertheless.

These sprints typically consists of four 10-15 lap sessions. So are you telling me that after the initial 7-10 laps of the initial session, the grip levels drop significantly?

I don't mind spending the extra expense or the shorter life expectancy but I was under the impression that the grip levels stay pretty constant throughout the life of the tyre (at least until you reach the indicator).

 

what size rims are you using? cause I was wanting some DRs

 

In my experience, the ULTIMATE grip levels for both slicks or non-treaded R-compund tires drop slightly after the initial heat cycle. We're talking about fractions of a second, not enough for most drivers to notice (unless its a qualifying session and I'm looking to plant the car on the pole). The problem is, after that initial heat cycle, slicks need to cool down for a couple of hours (preferably overnight) to allow them to cure. The problem comes if you take them out for another track session after an hour or so. Then you run the risk of overheating the compound and the grip can get greasy.

 

When you talk about one "heat cycle" do you mean one session of say 15 laps?

If I attend a trackday consisting of 5 sessions or "heat cycles", then do I need 5 sets of tyres to prevent slippery tyres?

If that's the case, I might stick to my R-Comps.

 

A racing tire has a limited number of heat cycles before grip is reduced to the point that you're not getting the benefit of a "race" tire. Typically for DOT-R tires its 40 to 80 heat cycles. A heat cycle is one interation of the tire getting up to temperature (150 degrees or higher I think) and them cooling back down. For a track event its one lapping session. For autocross, its usually counted as one day.

So, in your example above, the one 15 lap session counts as one heat cycle. If you do 5 sessions in a day, that's 5 heat cycles for that day. The grip difference between the first 10 heat cycles in a tire and the next 10 is not significant unless you're competing at the top levels of whatever motorsport you choose. The grip difference between the first 10 and the last 10 is significant and noticeable. The tire can usually still be run on the track if its heat cycled out, it just won't stick as well as it did originally.

EDIT: True slick racing tires typically have about half the number of heat cycles as a DOT-R tire. There are exceptions to this depending the the tread compund and slick construction. Hoosier bias ply cantalievered slicks seem to wear like iron.

 

Thanks for your feedback. I know with R-Comps I've used in the past, I've just used them until I reach the tread wear indicator.

Is this the same case for slicks? That is keep using them until the small "holes" are gone?

 

That's just when they are getting good, unless they are heat cycled out. That question is: what are you comfortable with? If you want to run your race tires down to chord and the sanctioning body allows it, go for it. If you want to put 5 heat cycles on your tires and then get a new set, that's fine too. Its all up to you and what your racing goals and budget require.

 

To get the most performance from Goodyear slicks, we've always used a tried-and-true practice: on 'stickers' (ie brand new slicks with the factory label still attached), run two laps at 6-7/10s. Then two-three (no more) laps at the limit (again, these are the fastest qualifying laps you'll EVER get out of the tires). Take one cool-down lap and bring the car into the pits. Promptly remove the tires and store them in the trailer, preferably overnight.

If you take care of the first heat cycle, slicks have an extremely consistent performance cycle. Depending on the roughness of the circuit you're on, you can run the tires down to near the oval wear indicators with little dropoff in performance. If you run them for 15 laps the first time out and just leave them on the rest of the day, you'll be wasting your money.

I think John already asked the question: what are you comfortable with? Slicks do take some additional effort to get the most out of them. Think of them as an extremely specialized tool. In any form of racing, the higher you go, the more effort goes into it.

 

Ok let me see if I got this correct.

I buy a new set of slicks then for the first trackday that I take them out on, I run 2 warm up laps, then 3 quick laps, take them off the car and let it cool overnight.

If I heat cycle the tyre right the first time then for every subsequent track days, am I able to run them like R-Comps? That is, run the same set of tyres four to five - 10 lap sessions, with a 30 min rest between each session.....

I'm not concerned with overall longevity of the tyre (for example R-comps lasting 50 heat cycles as opposed to 25 for true slicks). BUT if I am only able to run them one heat cycle per day..........that won't suit my needs.

 

In my experience, that's correct. That first heat cycle makes all the difference. Getting them off the car and having another set of tires to use after that is key to gaining longevity. After that, slicks last much longer as the compound has been properly cured and you'll notice overall traction dropping off gradually.

 

Correct.

 

dkmura, would you recommend the same treatment for R compounds, like Toyo RA-1s? And if so, is there some way I can mimic this procedure on the street before going to the track, since I don't have two full sets of track wheels and tires? (Or a trailer to get them to the track if I did.) Drive hard around an empty parking lot somewhere for ten minutes?