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Noah930's Avatar
 
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Anyone ever feel overtired?

Anyone ever feel like they're running too much tire for their car? That going beyond the stock 205/50/16 and 245/45/16 actually served as a detriment to the handling? That they never seem to need that much grip, anyway, so the heaviness and sluggishness penalties in handling weren't worth the tradeoff?

I'm waiting on a set of 17x9 and 17x11 wheels. Realistically, the tires that I'll fit on them will be 245/40/17 and 315/35/17. (Partially because there aren't a lot of other tire size options out there.) For those of you who have gone this way, how have you found your handling to have been affected?

This is for a car that's pretty stock, so far. Eventually, I'll do the requisite header/exhaust/turbo/intercooler mods. And eventually (later this year?) I'll start to track the car at DEs. But for now, it's a street car that does most of its aggressive driving as a canyon strafer.

Has anyone tried 235/40 on the front, and 275/40 on the rear?
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Last edited by Noah930; 02-02-2009 at 10:38 AM.. Reason: spelling
Old 02-02-2009, 09:29 AM
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Yea, I don't really need a foot plus of tread on each rear but is sure looks good.

Sluggish? Add more boost.
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RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
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Old 02-02-2009, 12:40 PM
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My street tires are 225/45/17 and 275/40/17 and I like them.

My car is 99.5% track use so the street wheels need to get me there + as my rain tires.
The extra rear grip definitely help compared with the skinny 205/245 original size
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Old 02-02-2009, 01:30 PM
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275 / 315 means the steering is uber heavy, the car follows ruts in the road like a pit bull after a kid, and at full lock the fronts rub a bit.

But above 10 mph who gives a crap? ;-)
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Old 02-02-2009, 02:22 PM
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315/355 here and even just moving her around the lot at the shop the steering effort was minimal - and that's after coming straight out of my (now long gone with the poplar trimmed cup holders) 550i bimmer that had featherlight steering.

If you feel over tired you're not pushing it hard enough and it might not fit your driving style. Look at the 935's and 934's...look at their tires now go look at yours, your rear tires are comprable to the fronts on theirs. But that amount of tire is only needed if you're going to use it to the max.

But once you fit your new turbo/exhaust/cooler etc. you'll be glad you have the sizes you do.
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Old 02-02-2009, 08:47 PM
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Very true, Craig and Reaper. I think for track work (particularly with engine work) the wider tires would be vastly superior. But since my car is mostly street-oriented (and, in particular it's tight canyons of Malibu and Angeles Crest that I'm running), I was wondering if anyone felt that going with fat tires was too much grip, at the expense of tossability. Glad that above parking lot speeds you guys don't seem to notice much difference.
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Old 02-02-2009, 09:16 PM
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No.

I think there was a comment from Mark Donohue in "The Unfair Advantage" that while a tire's contact patch is only dependent on the car weight and air pressure, he still found that the biggest tire allowed by rule provide the best traction.

I can light my 315's up too easily
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Old 02-03-2009, 03:38 AM
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I built my car is steps which gave me a great opportunity to feel each change.
The widebody was first and I used 8 & 9 x 15" wheels/tires with spacers for a few months. With the warmed over 3.0L engine the car tracked better than narrow and was quite tossable.
Then I added huge 255/345 tires on 9 & 12 x15 wheels. BIG change. The car could take a corner faster than I could but fealt very "heavy" at slow speeds. I could no longer spin the rear tires. I loved the look did not like the feel.
Last came the turbo transplant. Everything fell back into line. The tires were needed as I could push the car so much quicker and found myself in a bad spot more than once. The car remained with that "heavy" feel as expected and was less tossable at auto-x speeds than with the skinny tiires.
A few times I got a wild hair for some Smokey and the Bandit shenanigans and slipped on the skinny treads. WHOA is that a smoke show, ha!
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'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
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Old 02-03-2009, 04:19 AM
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At parking lot speeds huge tires and the camber that must be used with them will make for very heavy steering, without a doubt. SUre is on mine.

Above 35 it all comes together and above 50 or so there is nothing else I would ever want.
The grip and balance from a 100% race suspension, big ass track tires, and track time experience is "tarmac crack" ...... I'll never go back.
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Old 02-03-2009, 07:39 AM
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Yes you can have to much tire.

We used to have to much tire on our 935 clone.. I don't recall the exact size now...

We could never get the tires to operating temp, even sliding the car all over the track, we never got the rubber above 160-170..

We reduced the tire width f&R and are now able to get the rubber hot and sticky.
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Old 02-03-2009, 11:51 AM
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This past year I put on a new set of Toyo R888 in 255/40-17 & 315/35-17s and went to the Texas Hill Country Rally. The old girl did well but she just doesn't have the tossable feel that I'm so used to in the Cayman.

I doubt I'll ever drive the 930 on the track again so I'd like to work on the low speed handling (sub 100 mph) and make her more fun to throw around.

I'm thinking of trying 235/45-17 and 275/40-17. Do y'all think it will make a noticeable difference considering I'd still be running 9&11.5" wheels? Anyone need some slightly used 255 and 315 tires if I do change?

Any other ideas for making a 930 handle more like a 911SC/Carrera? Currently it has 22/31 torsions, Bilstein sports, and adjustable sways.
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Old 06-19-2017, 11:15 AM
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Its more of a function of track width than tire size - I'd stay the same. I have 275/315 V710 for street use. Had a 911SC...whole different animal and you can't head that direction appreciably
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"930 is the wild slut you sleep with who tries to kill you every time you "get it on" - Quote by Gabe
Movie: 930 on the dyno
Old 06-19-2017, 11:23 AM
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I'm currently running 255/40-17's up front and 295/35-18's out back, no problem with steering effort, car handles great, rides firm but nice.

Admittedly, the 255's are a bit wide for how low my car is, and can rub a bit if the conditions are just wrong. The previous 245's were no problem at all.

As far as the need for excessive camber to make wide tires fit, if the suspension is properly modified for your intended application of tire size and ride height and suspension travel, camber is NOT a problem. I'm running .75 deg front camber and 1.5 deg rear camber, no big deal for effort.

Now my suspension is not stock, and my ride height is rather low....so take all of that with a grain of salt.

Mark

Last edited by full quack; 06-19-2017 at 11:58 AM..
Old 06-19-2017, 11:46 AM
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David i would totally be interested in your tires if u decide to go that route.Please let me know so i can stop searching.Thanks Kevin

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Old 06-19-2017, 12:53 PM
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Mark i love the way your car sits maybe you can give us a run down of your suspension up grades if u have not done so in a different thread.

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Old 06-19-2017, 01:24 PM
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Quote:
Originally Posted by David View Post
This past year I put on a new set of Toyo R888 in 255/40-17 & 315/35-17s and went to the Texas Hill Country Rally. The old girl did well but she just doesn't have the tossable feel that I'm so used to in the Cayman.

I doubt I'll ever drive the 930 on the track again so I'd like to work on the low speed handling (sub 100 mph) and make her more fun to throw around.

.
You're just getting old dude!
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Old 06-19-2017, 02:28 PM
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Quote:
Originally Posted by 9dreizig View Post
You're just getting old dude!
You're just saying that because my hair is the same color as yours now!
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Old 06-19-2017, 02:44 PM
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Originally Posted by kevin930t View Post
David i would totally be interested in your tires if u decide to go that route.Please let me know so i can stop searching.Thanks Kevin

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I just checked and it may not be that easy for me to find 235 and 275 R888's, but if I do I'll sell the others at a reasonable price
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Old 06-19-2017, 02:52 PM
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I know Continental had come out with a great tire in those sizes,you might want to look into them as thats what i am running on my 18s

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Old 06-19-2017, 03:02 PM
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Hey there Kevin,
Here is a copied section from a previous post I replied to,
The basic list is as follows...
1.) Raised front spindles 40mm.
2.) Custom length Von shocks and inserts with valveing for my specific torsion bars.
3.) 30mm/23mm torsion bars.
4.) Rebel Racing front control arm bushing replacement blocks.
5.) Rebel Racing rear pivot replacement bushings and torsion bar tube mounts.
6.) Tarrett 22mm adjustable sway bars front & rear.
7.) Wevo weld on rear sway bar mounts.
8.) Fikse custom 3 piece wheels 17 x 8.5 fronts, 18 x 11 rear.
9.) B.F. Goodrich comp-2 tires 255-40 fronts, 295-35 rears.
10.) Elephant Racing welded on bump steer correction system kit.
11.) Strut tower brace.
12.) Hawk HSP front pads, Pagid RSR Black rear pads, all new rotors.
13.) Full alignment & corner balance, with the car setup with the proper 1.5 degree front to rear rake angle.

That pretty much sums it up. Car sits with 2" clearance under the front spoiler....:}

Hope this helps you out.

Mark
Old 06-19-2017, 04:38 PM
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