Tyre Pressures - 996 C2 3.4

I'm in a bit of a quandry about what tyre pressures are a) recommended b) best for handling I am running "stock" 18" rims. Have found higher pressures give me more stable handling but result in a harsh ride over bumps. I installed a full new M030 suspension setup (inc roll bars, drop links, top mounts) last year. I have tried 38 F / 46 R which was good for handling but terribly harsh. Just dropped the pressures down to 32 F / 42 R and it started to be kinda vague or pronounced in sensitivity to camber/ defects / white lines. I'd be pleased to get your 2p :?:

36/44 all the time.

One of the first things I did was drop a few PSI. At 36/44 it ruins the ride, rattles your fillings out and is nervous over rough roads. Weird they recommend such high pressures - may be essential if you are v-maxing all the time or something. I run at 32 / 40 ish, transforms the ride. I don't experience tram lining or wallowing, but then I have replaced just about all the suspension arms, mounts and joints on my car except the rear dogbones (todo...). YMMV do some experimenting! http://www.pistonheads.com/gassing/topic.asp?t=892433

How do you go on with the insurance assessor when you've wrapped your car and the pressures are way down (28/32 as someone stated on pistonheads as being 'so much better and the car is a joy to drive')?

I have replaced front lower control arms...one was quite worn. Have a pair of coffin arms in boxes ready to fit....toss up whether to do front or rear pair first....front looking likely.

If this was part of an accident investigation you would be not in a good place. Running pressures below/above recommended would be cited as 'contributory' to the accident. Accident investigators and insurance assessors are not interested or employed to take 'joy' into account. :sad:

Would I be correct in saying that the recommended tyre pressures apply only to Porsche approved tyre brands and types?

The pressure is calculated taking into account the size and load rating of the tyre and the vehicles weight so all things being equal if you run a non "N" rated tyre with the correct size and load rating then the manufacturer recommended pressure will apply.

+1 +1

It would be a problem if the the investigator deemed low tyre pressure to be a contributory factor. I would hope that just because a tyre is a few PSI down from mfr spec they wouldn't be so blinkered to automatically assume that was the cause (as excess speed is often involved but not always the cause). "What tyre pressure?" is akin to "What oil?" or "do I have to run N rated tyres?" it will run and run! Loads of people run them a bit lower (loads of people smoke, doesn't mean its the healthy thing to do), have a search: http://www.911uk.com/viewtopic.php?p=634977 http://www.renntech.org/forums/topic/13017-996-tire-pressures-revisited/

There's also tyre wear and fuel economy to consider when deciding what pressure you want to run on after ignoring the safety aspect of it (over-heating and handling). Am I missing something or is the hard ride down to having a sportier suspension than most cars? Girlfriend's standard golf are up at 36psi are that's quite a soft ride (down to softer suspension :?: ) Isn't running at lower pressures fudging the comfort at the expense of handling? :dont know: Correct me if I'm wrong. ps. If you want comfort - buy a Jag :grin:

I dunno Alex. All I know is that my previous 350Z GT has similar size tyres (same fronts, one size down rears) and is a heavier car and ran 35PSI all round (granted this car has a more even weight distribution). When I first got my 996 on its 18" wheels (prev. 17") I pumped the tyres up and was really disappointed with the terrible ride (considering the 996 standard has softer suspension than the Z, and it was such a great ride on the 17" wheels). I googled it and found people were dropping the tyre pressure a bit, I did this and the ride was transformed. My last set of rear tyres wore evenly across the tread (continentals, fitted at 6mm tread as came with wheels). EDIT: Actually I think they wore a little more on the inside edges. Some people note when running 44PSI in the rears they wear down the middle: http://www.pistonheads.com/gassing/topic.asp?t=918395 Your experience may well be different to mine.

Just to give feedback on results of experiment. I upped tyre pressures to 36 front and 44 rear using my calibrated tyre pressure dial gauge. The first drive out early morning was on reasonably smooth A-road at very much at or below the 50 or less liimits for 25miles each way. Car felt planted, responsive and with no undesirable querks or unusual handling traits. Later same day i took car on some twisties with poorer surfaces in parts, with much higher bursts of speed. I felt i had to make some steering corrections when riding over uneven contours or assymetric camber but the car responded immediately in all cases. Slight twitchiness over raised white lines or long runs of tarmac repair. Probably noithing unusual here however more likely to be suspension linkage bushes showing their age. I am working through obvious culprits like front tuning fork links and coffin arms all round. In short im pretty happy with the clear improvement in handling using these recommended pressures in summer. Im considering getting tpms system now i realise how critical the settings actually are.

I didn't think the insurance company would check your tyre pressures if you crashed - if they do then that's a new one! Regarding tyre pressures.... everybody has their own preferences. It shouldn't really turn into a debate. I run the pressure that I LIKE and drive MY CAR on the road quite happily. The responses in this thread are (mostly) doused in testosterone all the joy has gone from this forum. For tyre pressures/oil/tyres - it would be quicker to ring Porsche Main Dealer and follow their advice

Underinflated tyres are more likely to cause tyre blowouts. 36/44.