13" tires for autocross/track/street

[yellowss7]

I run Hoosier bias ply slicks on my 2000 yellow car.  The ten inch wide ones were THE auto cross tire in the R25B compound.   When I switched to tracking the car I used the same tire and compound but did go with a slightly larger Circumference tire to give me a little higher top end.  Look at my signature pic to get an idea.  
I can run the ten inch wide slicks as they fit easily under the clams.  
 

I run Michelin radial slicks on my Orange car,  and there is a difference to me in feel as the bias ply slicks seem more progressive to me vs the radials.  Then again the Michelin’s aren’t ten inch wide.  Maybe nine at the rear.
 

 

[sf4018]

+1 for Hoosier slicks for the track, the Hoosier Formula 2000 radials 43370/43380 R35 compound are about 5 seconds faster than the ZZRs at Barber. They also started selling R55 compound recently. 

[Croc]

14 hours ago, Pokey said:

....but researching further it looks like Hoosier bias slicks will retain the same ride height as the ZZS/ZZR.  I find this attractive as switching back and forth won't require suspension changes.  

 

@Pokey  Correct - I selected to continue the same rolling diameter as the Avon ZZR/ZZS as I did not want to have any suspension changes or inadvertant gearing effects.  I could add some negative camber on the front to enhance the way the Hoosiers work but I have not felt the need for that.  

[Kitcat]

Just to mix things up: I run 15” wheels in back, (225/45/15) and 13” up front(185/65/13), with Hoosier R7s(in the dry only). Pure track car. It came with the staggered set up from Beachman Racing, which  prepped it for the track.

 

When I bought it in 2012, Goodyear cantilevered slicks were the race tire of choice. My front tire AND wheel combo weighed in around 19lbs. Unfortunately, Goodyear stopped making those tires. The Hoosiers R7s are not as good, but very close.

 

As I recall, the bias ply Hoosiers provided the best grip and were the most forgiving (no sudden break-aways at the limit). And are lighter. But didn’t last as long.  But this was back “ in the day” and radial tires have kept getting better, so?

[Pokey]

On 6/30/2021 at 6:22 AM, Kitcat said:

Just to mix things up: I run 15” wheels in back, (225/45/15) and 13” up front(185/65/13), with Hoosier R7s(in the dry only). Pure track car. It came with the staggered set up from Beachman Racing, which  prepped it for the track.

 

@Kitcat, the 15" rears are an interesting idea.  I wonder if Bruce went that way for the selection of tires available or for gearing - my final gear is 3.91 so the 2" increase in diameter over my 215/55x13 rears might be nice for the track.

[Kitcat]

Since mine was set up for SCCA racing, he had to comply with their (arbitrary) rules. The Caterham wheels were limited to 13x6” in the rear, 13x5.5 in the front. So clever tire mfgs came up with huge, cantilevered tires that fit on the tiny rims.
 

Unfortunately, they stopped making those tires. So I switched to 15x7 wheels with 225/45-15 tires. This approximated the dimensions of the cantilevered tire. But the replacements were still not as wide as the cantilevered tires. And the new  set up added 10lbs, per corner (24lbs. v. 34  lbs).

 

Here is a side by side shot, with the Goodyear cantilevered slicks on the right, the 15” R7’s on the left. And a shot of the muffin-top style of the Goodyear’s.

[Pokey]

Just to tie a bow around this one, I decided on the ZZR.  I had also asked Mr. Beachman his thoughts on tires, and with my relative lack of track experience he suggested I stay away from slicks for now.  Coincidentally, Caterham emailed the same day Bruce responded letting me know the ZZR were finally in stock so I placed an order before they sold out again.

 

 

[Bartman]

Hey Greg,

 

I got ZZR Avons 185& 215 from Roger Kraus Racing in CA, they had them in stock, shipped fast and were super nice to work with, just FYI.

 

Bart.

[Pokey]

Thanks Bart.

[Pokey]

I'm curious about the process folks choose for preparing a new tire for track use.  Hoosier provides instructions for the initial heat cycle of the R7 that includes letting the tires rest for at least 24 hours after for reasons that seem sound, but Avon just describes an initial scrub in consisting of roughly the same process as the Hoosier but without the rest period.

 

I heat cycled my new ZZRs in the first session and set them aside to give them the rest that Hoosier describes but had a tire failure in the next session so put the ZZRs back on.  Just curious if it really matters, at least for a tire like the ZZR.

[Croc]

 

I have never bothered with the rest cycle.  Some slick tire manufacturers recommend it, some don't.  Se7ens never seem to trigger the same heat cycle intensity in slick tires that other heavier cars do.  

[Pokey]

On 7/31/2021 at 11:31 AM, Croc said:

 

I have never bothered with the rest cycle.  Some slick tire manufacturers recommend it, some don't.  Se7ens never seem to trigger the same heat cycle intensity in slick tires that other heavier cars do.  

 

Thanks @Croc.  

[Kitcat]

Tire Rack swears it is critical. Of course they charge $15, per tire, to heat cycle new tires, so? I have always done it to be safe. But, like you, I ended up needing to skip that step once and saw no adverse results.

[fastg]

I attended a tire 101 given by Jonny Miller the ex-TransAm racer, he now runs a track tires service. He said the cook them in an  oven is useless, that is not a heat cycle. A heat cycle is when you move and manipulate the rubber and carcass to generate internal heat.  

 

Sighted a Kitcat in the wild, driving a Miata at Summit point. 

 

Graham 

[John B]

Are ZZR's better on track than Hoosier R7's, or A7's?

 

I think I had A7's last time and they seemed to be holding up relatively well.

Edited September 1, 2021 by John B

[CarlB]

Once upon a time a long time ago I was a Goodyear Race Tire Dealer. As a dealer we were given training by Goodyear and in my case Penske tire my distributor. The Track tire guy is correct about heat cycling tires. They have to be run on the car. Heat cycling tires makes them harder. If the car is getting the tire close to the temperature the compound will over heat, waiting makes the tire harder and stand up to the car better. If you follow Indy Car they talk about using scuff tires or new tires. The performance of a scuff might be better if the compound is slightly too soft. 3500 Pound stock cars with relatively skinny tires put sticker tires on and do not beak them in. They sometimes use scuffs. Putting a few laps with a cool down on new tires is a good idea, but if you can't it isn't a big deal. the break in gets the surface scuffed up so it will grip. It gives the driver a opportunity to make sure there isn't anything wrong, and it gasses some of the solvents used in the manufacturing.  Even Hoosier's softest compound R25B doesn't get worked hard on our cars. Give them a slow warm up a few laps and a cool down. Inspect them to make sure everything is good and go out in the next session ready to go fast.  

[KnifeySpoony]

Bumping this to get some input from you experts. I have been running OEM ZZS on my 420R - have 5 days on them thus far. Still lots of rubber on them, though the fronts are chunking a bit. Could run them for another 5 days easily. They feel good, nice and progressive; the car is fast but also super fun and playful on them. That said, I'm thinking of "upgrading" to ZZR just for curiosity, and for laptime bragging rights of course. They have 3 compounds now - A64, A24, and a new 333 "extreme" compound. From reading this thread (and others) it seems even the A64 would be a big upgrade over my ZZS, so I'm wondering if I should go with them as the next step up, or go all the way to the A24. I don't really street drive the car (and it never sees rain), BUT I do drive it to the track (about 60miles away). Any thoughts how the A24 would do driving to and from the track, in terms of wear? Are they super soft? I don't want to destroy them on the freeway just getting there. Also how many trackdays would be typical for them to last? (most days I do are five 20 min sessions) I think I'd be happy with as little as 4-6 days if they are very fast. If they only last 2-3 days, it's probably not worth it just for the bragging rights, at least not routinely. I can only assume the "extreme" compound is even softer and just a qualifier, so probably not for me at all...

 

Thanks

[Croc]

 

 

My comments are already in this thread.  As one who has tried the ZZR and like them, I suggest you jump into the deep end and go for the A24 compound.  

 

A lot of wear issues really depending on the track.  I can get double your wear life on the ZZS on my 420R in the UK.  I assume that is because of the smoothness of the tarmac and not because I am a better driver.  So wear is going to be a very personal thing.  Only way to find out is slap a set on and go for a drive.  

 

 

[BlakeJ]

My experience switching from the A64 ZZR to the A24 ZZR was that it made a significant difference in grip at the track. I also drive the car on the street with the A24's, but only in good weather, and don't find that street miles are wearing the tires excessively. The biggest problem I have (with both compound ZZR's) on the street is that they're don't get warm enough.

[KnifeySpoony]

Ok that makes me feel somewhat more comfortable with running them. I have read on UK forums about the A24 being done in a weekend at the track, or just one lap wonders, which suggests that they are impressively soft. So my concern is that they were a true "qualifier". Meaning they're good for just a lap or two then they overheat. And then wear like soft cheese. If that's not the case, I may try them.