Inflation pressure 18" wheels??
02-28-2002, 08:30 PM
#16
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[quote]Originally posted by Ben in Plano, TX:
<strong>I run 34 front/36 rear in S-02's.
Ben</strong><hr></blockquote>
Sounds similar to me. Using Bridgestone S-02s, starting cold pressures of 32 front / 34 rear consistently gives me 40 psi all around on track days.
For street driving, I start a bit higher, around 34-36 front / 36-38 rear, with the understanding that pressures will increase about 3-4 psi.
BTW, I've tried 44 psi rear, and feel that it is much too high, regardless of what the factory says.
<img src="confused.gif" border="0">
<strong>I run 34 front/36 rear in S-02's.
Ben</strong><hr></blockquote>
Sounds similar to me. Using Bridgestone S-02s, starting cold pressures of 32 front / 34 rear consistently gives me 40 psi all around on track days.
For street driving, I start a bit higher, around 34-36 front / 36-38 rear, with the understanding that pressures will increase about 3-4 psi.
BTW, I've tried 44 psi rear, and feel that it is much too high, regardless of what the factory says.
<img src="confused.gif" border="0">
03-01-2002, 12:59 AM
#18
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Rocket,
I am driving a 1997 993 C2 coupe with the optional 18” Factory Technology wheels.
Tires are Michelin Pilot Sport Cup (10% stickier than S-02s) in stock 225/40 265/35 size.
Using advice from this forum, on my first track event I reduced the pressure from the factory 36/44 PSI spec. I started with a cold pressure at 34/40 PSI. I was being conservative and under the expectation this would be high and I would work lower. With this pressure, the tires were wearing a little bit too far over the edge so I went up to 36/42 cold. I believe if I was running 30 front and 34 rear cold I would have been driving too far down the side wall even though my car has extra negative camber.
Maybe if I was using a tire that did not stick as well, the lower pressure would be OK?
Maybe the Michelin Pilot Sport Cup has a less rigid wall?
I don’t dispute your experience, just reporting my findings!
Regards,
George
In sunny Arizona
P.S. No pot holes to damage my wheels here. Just dips which cause me to BANG my front underside (OUCH!).
I am driving a 1997 993 C2 coupe with the optional 18” Factory Technology wheels.
Tires are Michelin Pilot Sport Cup (10% stickier than S-02s) in stock 225/40 265/35 size.
Using advice from this forum, on my first track event I reduced the pressure from the factory 36/44 PSI spec. I started with a cold pressure at 34/40 PSI. I was being conservative and under the expectation this would be high and I would work lower. With this pressure, the tires were wearing a little bit too far over the edge so I went up to 36/42 cold. I believe if I was running 30 front and 34 rear cold I would have been driving too far down the side wall even though my car has extra negative camber.
Maybe if I was using a tire that did not stick as well, the lower pressure would be OK?
Maybe the Michelin Pilot Sport Cup has a less rigid wall?
I don’t dispute your experience, just reporting my findings!
Regards,
George
In sunny Arizona
P.S. No pot holes to damage my wheels here. Just dips which cause me to BANG my front underside (OUCH!).
03-01-2002, 03:30 AM
#21
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[quote]Originally posted by George Helser:
<strong>Maybe the Michelin Pilot Sport Cup has a less rigid wall?</strong><hr></blockquote>
My tire guy had me feel the sidewall difference between the Michelins and S02s when I was choosing my road tire: the S02s are MUCH stiffer......my car came with S02s and a stock suspension, and I found the ride a tad bone jarring even with low tire pressure.
We may be talking apples and oranges, though. I assumed, perhaps incorrectly, that the original poster wanted road specs, and some of the responses have been directed toward the track. If my car was just a street car, I'd run Michelins at 36/44, and if I wanted to go to the track, I'd put back on the S02s and drop the pressure as Anir has.......
<strong>Maybe the Michelin Pilot Sport Cup has a less rigid wall?</strong><hr></blockquote>
My tire guy had me feel the sidewall difference between the Michelins and S02s when I was choosing my road tire: the S02s are MUCH stiffer......my car came with S02s and a stock suspension, and I found the ride a tad bone jarring even with low tire pressure.
We may be talking apples and oranges, though. I assumed, perhaps incorrectly, that the original poster wanted road specs, and some of the responses have been directed toward the track. If my car was just a street car, I'd run Michelins at 36/44, and if I wanted to go to the track, I'd put back on the S02s and drop the pressure as Anir has.......
03-01-2002, 05:18 AM
#22
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Hi All,
running SO3 235/40fr & 285/30re on 996 C2 Cab. MAX PSI written on tire sidewall is 40PSI so I run 29fr & 30re! I found these combos to be best for me on fast streets/comfort & tire wear (done 10k miles & rear is about 60% worn whilst front is about 25/30% worn). After a spirited fast street drive PSI rises to 36fr & 38re – keep in mind MAX cold air is 40PSI.
Pot holes maybe a problem but can’t say I run into many. Often if I see a pothole I slow down as you should – even if travelling at high speed.
I had previously tried following combos;
36fr/44re – death wish handling! Car was by far too sharp on steering
30fr/32re - good all round handling but oversteered too easily
32fr/34re - car was too twitchy from 70mph +
30fr/30re - 2nd best all round settings. Steering was marginally too light.
32.5fr/30re - too nervous up front. back held well
30.5fr/32.5re - too nervous at rear. front stuck well and steering was tad heavier.
Manufacture recommendations just does not work for me. On my previous Porsche, a 2.5ltr Boxster, I went through similar trial & error and found optimum PSI to be always less than manufacturers figures. I tend to see Porsche PSI recommendations as just that, recommendations!
running SO3 235/40fr & 285/30re on 996 C2 Cab. MAX PSI written on tire sidewall is 40PSI so I run 29fr & 30re! I found these combos to be best for me on fast streets/comfort & tire wear (done 10k miles & rear is about 60% worn whilst front is about 25/30% worn). After a spirited fast street drive PSI rises to 36fr & 38re – keep in mind MAX cold air is 40PSI.
Pot holes maybe a problem but can’t say I run into many. Often if I see a pothole I slow down as you should – even if travelling at high speed.
I had previously tried following combos;
36fr/44re – death wish handling! Car was by far too sharp on steering
30fr/32re - good all round handling but oversteered too easily
32fr/34re - car was too twitchy from 70mph +
30fr/30re - 2nd best all round settings. Steering was marginally too light.
32.5fr/30re - too nervous up front. back held well
30.5fr/32.5re - too nervous at rear. front stuck well and steering was tad heavier.
Manufacture recommendations just does not work for me. On my previous Porsche, a 2.5ltr Boxster, I went through similar trial & error and found optimum PSI to be always less than manufacturers figures. I tend to see Porsche PSI recommendations as just that, recommendations!
03-01-2002, 06:36 AM
#23
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I got my C2S with new P Zeros in 225/40, 285/30 x 18, and ran 36/44 for first 4k miles (interestingly, though, the OPC had set pressures to 36/40).On checking the wear patterns fairly closely, rears were wearing more in the centre. Handling tended to understeer, esp on track.
So I went to 36,40 and handling is a better compromise - still get the crisp turn-in, which you would lose dropping the front pressures. Of course mine is a little(!) lower than a US car with standard RoW S suspension.
HTH, Cheers, Maurice
So I went to 36,40 and handling is a better compromise - still get the crisp turn-in, which you would lose dropping the front pressures. Of course mine is a little(!) lower than a US car with standard RoW S suspension.
HTH, Cheers, Maurice
