tire widths???
Burning Brakes
Joined: Dec 2006
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Originally Posted by elh0102
I think you will find much greater differences in handling qualities by changing tire type, as opposed to a one-size change. I'm interested in getting some 18" wheels for track use, but I'm not sure if I will increase the width. In feeling around the front strut of my car (997S), I have probably 3/4" of clearance with the strut at the sidewall, which is plenty. But, at the top inside corner, there is much less clearance with the bottom of the spring perch. I can just squeeze the tip of my little finger in there. So, given the same profile, a wider tire is also going to be taller, and I don't think you can go far in that direction. I have maxed out the front camber, which isn't much, and I would never change that to get more tire clearance. Given the experience of others, I think the answer is yes, you can probably go a bit wider, but I'm not sure you will feel any effect. Stickier tires are probably a better solution if you want more absolute grip. If you want to change the balance towards less understeer, you may have to invest in some suspension work to get more front camber. IMO, not worth it.
Dave
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From: Connecticut
Here's another example. I ran street 245/275 PS2s on OEM 18s on my E46 M3 on very cold or wet track days. Quite a bit of understeer. On nice days I ran 4x 265 PSCs on 9" OZs and boy, the square set-up was nice. I used the 20mm provided OZ spacer in at the rear wheels to leave a little understeer there (safety valve) - so tire position was about the same as OEM, but the rubber was square. In other words, not only a wider tire up front, but a narrower one at back - went from 30mm difference to 0. Very different animal just from front / rear tire size changes.
Instructor
Joined: Sep 2006
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Originally Posted by Dave07997S
I have to disagree with you here...on my E46 M3 going to a RAC monolite RG4 wheel with a 9" wide front wheel fitted with a 255/34/19 vs. the 8" stock wheel fitted with a 225/40/19 front dialed almost all the push out of the car before I even touched the suspension. I am sure moving to a 9" wide front wheel with a wider tire in front will help quite a bit on a 997, just look at the GrandAm cars and such...
Dave
Dave
Burning Brakes
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Originally Posted by elh0102
I too come from an E46 M3 background. I found that 265 or 255 all around was a very good setup, so I agree. I don't have enough experience yet with the Porsche to know what works best. But, it has so much less push in stock configuration than the M3, and with less weight up front, I would not expect the same relative benefit, but, I haven't tried it yet. There doesn't seem to be enough room with the 997 to increase the front width as much as I did in the M3. But luckily, from my perception anyway, it doesn't seem to need much improvement.
Burning Brakes
Joined: Dec 2006
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Originally Posted by RonCT
Here's another example. I ran street 245/275 PS2s on OEM 18s on my E46 M3 on very cold or wet track days. Quite a bit of understeer. On nice days I ran 4x 265 PSCs on 9" OZs and boy, the square set-up was nice. I used the 20mm provided OZ spacer in at the rear wheels to leave a little understeer there (safety valve) - so tire position was about the same as OEM, but the rubber was square. In other words, not only a wider tire up front, but a narrower one at back - went from 30mm difference to 0. Very different animal just from front / rear tire size changes.
I had something similar on OEM 19's was the 245 width tire and a 8" wide rim just wasn't optimal. The RG4's with their aggressive offset and the 9" wide wheel and 255's was such a cure for this on a street car. I don't even thing a 235 width tire is properly supported by just a 8" wide wheel. The tire looks a little pinched.
Dave
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That's what I'm looking for based on observation over 4 years of watching 996 and 997 cars (and talking with their owners), what I've read, and my own experience with staggered and square setups on the track.
There's a reason for staggered 235/295 that comes on the car. Lots of weight in the back and you want to be able to hook it up. One of the reasons these cars don't come with LSD from what I've read is how much grip you have back there. But, there's also some "Safety Factor" understeer built in. So, in theory if you kept 295 in back and went to 245, you'd have less and thus more overall grip (more contact patch). At some point you get to "Neutral" and then the next step is oversteer (which makes me nervous).
There's a reason for staggered 235/295 that comes on the car. Lots of weight in the back and you want to be able to hook it up. One of the reasons these cars don't come with LSD from what I've read is how much grip you have back there. But, there's also some "Safety Factor" understeer built in. So, in theory if you kept 295 in back and went to 245, you'd have less and thus more overall grip (more contact patch). At some point you get to "Neutral" and then the next step is oversteer (which makes me nervous).
Burning Brakes
Joined: Dec 2006
Posts: 781
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Originally Posted by RonCT
That's what I'm looking for based on observation over 4 years of watching 996 and 997 cars (and talking with their owners), what I've read, and my own experience with staggered and square setups on the track.
There's a reason for staggered 235/295 that comes on the car. Lots of weight in the back and you want to be able to hook it up. One of the reasons these cars don't come with LSD from what I've read is how much grip you have back there. But, there's also some "Safety Factor" understeer built in. So, in theory if you kept 295 in back and went to 245, you'd have less and thus more overall grip (more contact patch). At some point you get to "Neutral" and then the next step is oversteer (which makes me nervous).
There's a reason for staggered 235/295 that comes on the car. Lots of weight in the back and you want to be able to hook it up. One of the reasons these cars don't come with LSD from what I've read is how much grip you have back there. But, there's also some "Safety Factor" understeer built in. So, in theory if you kept 295 in back and went to 245, you'd have less and thus more overall grip (more contact patch). At some point you get to "Neutral" and then the next step is oversteer (which makes me nervous).
Dave
Three Wheelin'
Joined: Jul 2005
Posts: 1,257
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Originally Posted by mountainmaniac
How would handling of a C2S be affected by slightly wider front tires (i.e. 245)? Would they even fit? And is there any noticeable handling difference with 305's on the rear rather than 295's?
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