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17" tires size for autocross

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Old 02-21-2019 | 03:47 PM
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Default 17" tires size for autocross

I've got a set of 17" Turbo Twist wheels sitting in the garage, and I'm thinking about getting some sticky tires for AX. I've seen R888R available in stock sizes, but I'd actually prefer something with a treadwear rating between 101-200.

Looks like Advan AD08 night be an option, but TireRack doesn't have the stock front size in stock.

Any suggestions? How much wider than stock can I go on those rims?

Thanks.
Old 02-22-2019 | 07:05 AM
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Bridgestone RE71R. It's all I use anymore. Wears out very fast though.
Old 02-25-2019 | 09:58 PM
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Thanks. I'm really looking for for advice on size.

Can I run 225/45/17 up front vs the stock 205/50/17? Would be nice to get a little more rubber up there to combat understeer. Seems like there isn't much choice in larger sizes for the rear.


Old 02-25-2019 | 10:03 PM
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The contenders at Tire Rack
Old 02-26-2019 | 11:43 AM
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If you have problems with understeer, get a 17x9 set for the fronts and run at least 245s. Take out the silly amount of rear toe these cars have, and get all the front camber you can, then get some more.

A 996 is worlds better on square 245s than the hilarious 225/285 OE stagger, at least for autox. The factory alignment and stagger really neuter the car, so waking it up is very rewarding.

I went 17s because you used to be able to get 245 conti challenge or ? slicks for free with tons of life left- but good luck getting them warmed up at autox unless you can hot lap
Old 02-26-2019 | 01:22 PM
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I actually put 255s on the front of my 03 4s in order to eliminate the low speed understeer. Whatever you do, go as wide as possible in the front, and max out your front camber, should be around -1 degree front. I would recommend going with 18s and doing 255 front 285 rear.

If you use any tire other than the RE71, you will be uncompetitive in A street or Street Touring. Branding the RE71 a 200 wear tire is the greatest trick any tire manufacturer even pulled. They are pencil eraser soft, and wear faster than Michelin Cup 2s, literally.

Edit: just so you're aware, unless you have a 40 AE car on $8,000 coilovers AND you're a national level driver, you will never be competitive in A Street or Street Touring X. 996s simply cannot compete in A Street, and wouldn't even be competitive in B Street, and its a shame. Also, you'll get docked in touring for having a rear tire over 265, which is ridiculous. E46 m3s, S2000s, 987S and C6s are simply out of reach due to their balance, weight or the tire rules. Therefore, just try to get the car to a point where its enjoyable for you. For me, it meant getting rid of the incredibly frustrating low speed scrub understeer, and then just trying to make every lap better, and not worrying about getting absolutely smoked by stock BRZs, or tying well driven NA miatas...

Last edited by orangeman; 02-26-2019 at 01:46 PM.
Old 02-26-2019 | 03:46 PM
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Thanks for the input! I'm going with the wider fronts (225/45/17) and will pair with the stock rear (255/40/17).

This is just for running with my local PCA AX group. I already know I won't win anything, regardless of what tires go on the car. That being said, sticking with 200 TW and the 17" wheels does at least keep me in AX7 due to the other mods on my car.

I should revisit the alignment on my car, as I'm sure it could be made more aggressive. Initially, I didn't do that as I was doing longer drives with the car pretty regularly. Now, however, I'm mostly driving to AX and around the local roads, so I'd rather dial in more responsiveness.
Old 02-26-2019 | 04:41 PM
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225/45/17 will fit on the front 7x17 ET 55 wheels, 986 Boxsters run the same OEM tires 205/50/17 F 255/40/17 R as the 17" 996 tire and lots of us Boxsters run 225/45/17 in the front, it helps quite a bit.
Old 02-26-2019 | 05:27 PM
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Originally Posted by vitaminC
That being said, sticking with 200 TW and the 17" wheels does at least keep me in AX7 due to the other mods on my car.

I should revisit the alignment on my car, as I'm sure it could be made more aggressive.
That's great! I put 235s on the front of my 987s and 255s on the rear actually made it a bit tail happy. Might be a good set up if you plan to do a lot of auto X and really want to rotate. You can also try disconnecting your rear sway, I know the box guys all do that.

I have zero toe front, the tiniest amount in rear, max neg camber front and -2* rear on my aggressive street C4S and I love it, but it do tramline on the highway a bit.

Those boxes can really move! At our last Porsches vs corvettes, the winner, neck and neck with a $120k C7 Zo6/o7, was an exceptionally well driven 987 BASE with an auto!
Old 02-26-2019 | 07:51 PM
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My '99 996 currently rides on MY02 Carrera 5-spoke wheels with some 380TW tires (in stock sizes) and it provides for plenty of tail-happy sliding and rotation! It's fun, but not the fastest way around the course. At the AX school last summer I had a lot of fun drifting the car during the exercises, but for the actual events it would be better to have the car turn
Old 03-04-2019 | 11:05 AM
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If fighting understeer is the goal, I think a more aggressive alignment is a good place to start as well. Orangeman's specs above look similar to my alignment (though I think I carry a little more toe-in at the rear). A lot of people run toe-out on the front, but I think that hurts my ability to trail brake the car. These cars are front-camber limited, but I read a trick somewhere on this forum and it's been great for me. The holes for the front shock mounts are mildly slotted on the 996.2 and I think that's the case for all 996.1. You can jack up a front corner, loosen the three bolts, slide the mount inboard, then torque them down. Repeat on the other side. Then get the car aligned. Takes 15 minutes, and I got about 0.5 additional deg of negative camber. It's fundamentally the same thing camber plates would do, just to a lesser extent.

No matter how much tire you put up front, there still isn't much weight up front unless you put it there with the brake pedal. More tire helps, more front camber helps (counterintuitively, some even run a stiffer front bar so you keep that front camber when the car is loaded up in a turn), tire pressures are important (I run 30f, 35r for autox 90% of the time), I'm convinced driving style is most important though.

I run 225 fronts and 285 rears and have all the oversteer I can handle. I still get understeer at times, but that's down to when I don't get my inputs right. FWIW, I think re71r are the way to go, no question. Not sure about your local ambient temps, but getting heat into an r888 can be difficult with long waits between runs. Re71r build heat fast and I'm not convinced they're really less grippy than an r888, just less heat tolerant if you're at a track day. I've used mine at autox/trackcross in temps from 29f - 93f over the last few years, ordering my 4th set this month.

I know that went all over the place and you're trying to confine the discussion to tires, but the 911 is a weird animal and there is generally no silver-bullet single factor-fix for handling changes. In a car that's been developed for as long as the 911 has, I'm convinced that it takes a multitude of thought-out small changes working together to make a result that's not worse than what you started with. Because I've defn made the car worse at times with my changes haha
Old 03-04-2019 | 11:48 PM
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Originally Posted by DeanClevername
If fighting understeer is the goal, I think a more aggressive alignment is a good place to start as well.
Thanks! Yeah, I really need to experiment more with setup. I've got all these adjustable bits on the car, I should turn the *****! (KW V3, Tarett GT bars, etc).

Once I get the new tires mounted and installed, I will go for a more aggressive alignment.



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