4 Kurves

Peter - what are the model Hoosier's that you run? Are they DOT legal tires?

Thanks,
Kevin

frayed

cos, it's the difference in rolling circumference/diameter. Your car cannot 'know' if it has different width contact patches or different aspect ratios.

NJ-GT

Cosmos:

As a reference, the rear Michelin in the GT3Cup is taller than the 305/35R18 Toyo and the car comes with ABS, but it comes calibrated from the factory.

I tested 245/335 just for curiosity at a local road, it's not my autocross setup, but the ABS was not an issue.

It makes a lot of sense that the ABS pinions at each wheel will be rotating at a different rate compared to the stock tires sizes. When brakes are applied, the sensors might be sending signals based on ABS pinions rotational rates, and the ABS computer will process those reading, responding to an incorrect input.

85Gold

Kevin,

They are A3SO5's DOT radial tires. The SCCA approves them for AutoX Stock class which need to DOT tires. The R3SO4's are the road race version and are also DOT approved. I run the 245/35's on the front as the 245/40 have a slight rubbing issue.

Peter

Z06

I tried the Toyo RA-1 today ....back to back with my MPSC....the Toyo had more grip. The Toyo were on my old Z06....275/335x18. The Z06 was sloppy compared to the GT3 but it had more grip.

I would also like to get a set of these Toyo RA-1.

perfectlap

have them on my Boxster. very sticky, they bite bite bite. at my first autocross in the Porsche, I got within a couple of seconds of some of the pretty fast guys and I'm not very good, neither was I trying very hard. I wanted a tire that was decent for daily duty (very short 5 minute commute) and decent for autocross and track. Just what the doctor ordered.
Bobwoodman and Frisby Race tire were the best prices I found. 275's were $260. 245's $250

Jim H.

Lots of good info. I still wonder why we can't just run RA-1s like they do in Speed GT. Obviously, if Wolf Henzler can win races at that level, they must have some combination that works "great". I personally don't know of a difference between the Cup Cars and the street GT3 that would prevent a similarly great setup with RA-1s to be run on our cars. Anybody know of a difference that would matter?

In fact, wouldn't it be great to know the suspension setup of Henzler's car as well? Ride height, toe, caster, camber, etc. Trader secret or obtainable? I know I'd be interested in a monkey see monkey do kind of way.

Z06

The difference is in the gearing...those cars have close ratio gearing.

NJ-GT

Wolf Henzler and all the other GT3 Cups on the Speed World Challenge are using the following specs:

F: Toyo RA-1 245/40R18 on 10" wheels
R: Toyo RA-1 305/35R18 on 12" wheels

Those sizes fit in our stock wheels and car pretty good, as long as no camber shims are used. The downside is the 26.4" rear tire vs. 25" stock tire. That will make the gearing longer (and it is long already). On that combo, this are the top speeds in each gear:

1st: 49mph
2nd: 87mph
3rd: 120mph
4th: 155mph
5th: 183mph
6th: 215mph

So, after 120mph is where the car will have the right gearing, and not below that, due to the power curve and the differences between gear ratios.

Toyo is supposed to release a 285/30R18 and a 295/30R18 this summer.

Anyway, the MPSC has more grip on dry conditions when both tires are up to operating temperatures.

frayed

Will be nice to have another R comp alternative in proper sizing. The Toyos, along with the MPSCs, Yok A048r, Pirella Corsa, Dunlop SS, can all be driven to/from the track, something you really don't want to do in a V710 or Hooter.

healeyg

my understanding is that the wheels being used on henzler's cup car are standard gt3 cup width: 9" and 11". 10" and 12" rims are the permitted "maximum" width for the cars under the series rules. if you look at toyo's web site, the ideal rim width for these tires is 8.5" and 11"

85Gold

Don't assume the Toyo is the best tire just because the Cup cars are using it. It is the Spec tire for a race series that all participants must run.

Peter

996FLT6

It's not the Henzler's car set up I want it's his driving skills. I know hands down he kill me in a spec miata. But back to the question of tires. I like the TOYO's alot and I've used yokohama's and toyo's on my gti and toyos are so much grippier then the yokes. I do like the Dunlops too but it's more for price then nething else and it's a better performer then streets. Hope TOYO is listening on making a tire for the GT3. Regards. Mike

Jim H.

85Gold - No assumption being made about best...The RA-1 is not the stickiest but it has great break away characteristics, is long lasting, and is reasonably fast. I think a lot of guys would use it if a proven set up could be found.

NJ posts some interesting data. In fact at my favorite club track (Putnam Park) the additional speed in third gear may be beneficial. On that track, in a 944T, most of the time you're in third gear and kissing the rev limiter at multiple points. So maybe a taller third would help (then again maybe not).

GT3 Nut

The taller rear tire WILL cause ABS and brake proportioning valve problems!!! I tried the Michelin European Cup slicks with taller rears. I had ABS failure and a red warning notice saying "brake proportioning valve!" (or something like that) I didn't get to read it real thoroughly because I was heading for the tire wall in T4 at VIR at that moment. The ABS system is not calibrated/set up the same as the Cup car. Be careful not to screw something up.
Just my experience and .02