Yellow996

Searched this topic and ended up with more questions than answers so, I just thought I'd ask for my application directly. I want to make the leap from R6s to slicks. Currently running:

1999 996
Front 8 x 18 245/35/18
Rear 10 x 18 295/30/18
R6s
GTB1 Class in PCA

I'm looking for a specific size, brand, etc. of slick that will not conflict with stock ABS functionality.

The size differences among manufacturers has me stumped. I'm not particular to brand.

Thanks for the help! As a new member, this site has been a wealth of information!

Veloce Raptor

Not sure where you are located, but you might contact Bob Woodman of Bob Woodman Tire. He knows his business!

DDun911

Time to go the mattress's ?

himself

Check with JR [JRGordonsenior here on Rennlist]. He put a 996 through the paces and should have a lot of info.

-td

Yellow996

DD...I'm all in after this! LOL

VR, I'm in PA. I will check with Woodman. Thx!

himself...I will PM him. Thx!

good hands

I just made the change and stuck with Hoosiers. The reason is that they have 305/645/18 and 250/650/18 and they are nearly identical as the 315 and 245's I ran with R6's. The 10 inch rim may limit you though. You almost need to make the transition to 11's and 9's or 8 1/2's. I also have tried the Yoko's in 280/650/18 and 230/650/18's. A little bit thinner in the rear but also a good tire . No problems ABS wise or with fitment. Plug and play.

DDun911

I run 11s and 9s if you want to try them on for size.

jakermc

I run 9 and 11 on my 996 so can't help you with specific tires for your rims but can help a little with your ABS question.

First thing to remember is that the ABS system is assuming the stock tire sizes are in place, so the closer you stay to that the better. Next most important thing is to remember that the tires are part of the entire suspension and set-up system and it's going to take some testing and tuning to minimize ABS issues. I don't think you can eliminate the problem completely, you are really just aiming to minimize conditions like black ice mode.

I found that hide height played a critical role. When I switched from Hoosier slicks to the taller rear Michelins and Yokohamas I found that my ABS issues got much worse. Part of that is the fact that I moved further away from the stock size but I also felt the rear becoming unstable under braking which seemed to further trigger ABS issues. Confirming my suspicions, my front brake pads wore out much faster than the rears when they had previously worn at the same rate.

Solution was to drop the rear ride height and raise the front. Dramatic improvement, braking is even better now then when the Hoosiers were on it. The taller rears were impacting weight transfer, causing instability in the rear, and triggering aggressive ABS interaction.

Moral of the story, no matter tire you pick things like ride height, spring rate, shock settings, etc. are all going to play a role in the braking performance. Approach it as a system and you'll find success in your set-up.

IcemanG17

while I don't know anything about ABS functionality, especially on a 996.... I can say this I LOVE SLICKS....they really are crack..... I thought the R6 was about as good as it got until I tried USED slicks....unreal the bump up in performance....

Having a 911, gives you lots of options..... The Yokohama GT3 cups run 240/650-18 front at 280-680-18 rears....the Pirelli is a step larger at 305/680-18 rear and 275/645-18 front.......Michelin Porsche N1 runs in the middle with 25/64-18 front and 30-68-18 or larger rear....

Another "urban legend" I did not find was that slicks are harder to control at the limit....far from it in my experience.....I found slicks much more forgiving than some Dot R's....or in other terms as the slip angle goes well beyond the ideal grip range, the available traction doesn't drop off as quickly....

Veloce Raptor

Hey Rob, did you get my email regarding the Villa?

jakermc

I did not. Nothing in my spam box either, please hit me up again.

Veloce Raptor

Re-sent, to the sbcglobal.net address.

jrgordonsenior

Just received your PM but will answer here......

I think Rob (jakermc) above makes some very good points. It really takes a system approach to get the best performance out of your tires and your car in general.

For starters the 8's &10's really limit your choices for slicks. Yes you can run 240's and 280's but they will underperform on those rims and are possibly even dangerous. 9's & 11's allow those tires sizes to work much better.

As for ABS issues, you're lucky in that the 99' cars don't seem to suffer the same 'black ice' mode as later mdels like the GT3's. Besides Hoosiers, Yokohama makes diameter options that are exact or close enough to never trigger that issue. Note that no matter what tire you're running if you stand on the brakes hard enough from 100 or so you can make the system activate. That's what it's designed to do. If you don't like it you can spend $12k or so on a aftermarket ABS system.

OK tires, I run Yokohama's 250/650/18's up front with 280/650/18 rears. Those diameters are exactly the same front & rear. I don't believe the 680 cup height rears work as well as the lower profile rears and I've tested all of them. Lower is usually better except maybe on steeply banked tracks like Daytona. Yokohama also makes a 230 or 240 front in the same diameter which would nicely on your 8" rims with the 280/650 rears. Their next largest size in rears is 320's which are way too much tire for your car.
http://www.bobwoodmantires.com/yokohama-a005/

Hoosier also makes appropriately sized tires for your car. They make 235/645 or 250/650 front to go with 285/645 or 305/645 rears. All of those diamteters are within .1 of an inch in size. Again I feel the 305 rear its too much tire for a 3.4 especially on 10" rims.
http://www.bobwoodmantires.com/hoosi...radial-slicks/

You didn't mention your shocks or springs package. With slicks you need a minimum level of stiffness to take advantage of their abilities. I'm not a big proponent of really stiff suspension, but I'd run a minimum of 400 front/600 rear with any slick and you need shocks valved to match. They don't have to be the most expensive multi adjustable shocks to work well, but they have to be valved and setup to handle the loads you're going to create. Additionally getting the ride height setup correctly makes a huge difference as Rob found out. Aero forces also will dramitically affect your car's performance. Are you running a wing and/or a later model front bumper cover?

As Rob said, the individual components work best as a designed system setup by a professional. You can waste lots of money expermenting yourself, or take some professional advise and only spend it once. Rob, myself, and many others herre can attest to that principal....

Yellow996

JR:

GREAT info!

To answer your questions: I have Moton Club Sport suspension, a GT3 wing, the 996 aero package with a GT3 front bumper.

jrgordonsenior

If you're going to test with the 8' & 10' here's what I would suggest....

Yokohama's are $100. less per set. I'd try their 230/650/18 front @ $360. per. I would use their 01 compound which is part # N2076. For rears I'd use their 280/650 @ $412. per. I would use their 02 compound which is part # N2390. Total cost of $1,544. + taxes, etc.
Note: The Yoko 230 front is the same size as Hoosier's 250 front. 9.72 section width vs 9.8, and tread widths of 9.06 vs 9.1. You can see that on the charts I posted previously...

For Hoosiers, I'd use their 250/650 front # 43825 in their R80 compound @ $ 409. per
For rears I'd try their 285/645 # 43855 also in their R80 compound @ $ 460. per. Total cost of $ 1,642.
Note: Many guys use the R100 compound in the rear tires. That's great if you have a Cup with a big wing and lots of WHP. I could never get them up to temp in my 99' even with a cup wing....

Club Sports are great shocks, I use them too. What spring rates are you running with them?.....