Tyre pressures
- Thread starter rpjg_1975
- Start date
I am running my 944 S2 on 17" Boxster (I think) alloys, and I would like to get an idea of what pressures I should be running the tyres at - I have made enquiries through the people who maintain it, but despite their expertise they are not quite sure. The tyres are 205 at the front 240 at the rear - car is solely used for weekend blats and track sessions.
Any ideas?
Any ideas?
That whole 44psi in the rear thing is nonsense. I know it's in the manual (for certain years), but all it does is makes the back overly loose. Even with standard tyres on a car that is suppsoed to have 44psi at the back you're better to go with the recommendation for other years (which I forget the detail of, but it's something under 40psi). 34psi all round is about right for 17" wheels, though as advised above some people go a pound or two either side.
Neil Haughey
New member
If you have been driving on track with new or nearly new tyres you should measure your tyre wear as a minimum aiming for even wear across the tread, or better still use a pyrometer and measure the tyre temperatures on the inside, middle and outside of the tread after each session. Your target should be to get within 20 degrees F across the tyre, typically the advice I have had is that it should be slightly higher on the inside presumably due to better airflow to cool the tyre on the outside. If you get the temperature distribution correct then you are running the correct tyre pressures for your car and tyre combination on the track you are driving on, period. An old fashioned but very good version of measuring the tyre wear across the tyre is to put a chalk line down the crown of the tyre (from the last inch of tread down to the side wall). When you come in after a short session the only chalk visible should be on the sidewall and perhaps a little up the crown, if chalk is still on flatter section of the tread then the tyre is over-inflated. If chalk is only on the sidewall then the tyre is likely under-inflated and one should increase the starting pressure for the next session until you go to far then you will have a pretty clear idea about what the ideal pressure. The great thing about the chalk method is one can use it equally well for getting perfect tyre pressures for the road as well as track driving. Sorry for the overly long technical post but you did mention track driving so the above is a list of 3 of the methods one can use for getting it right. Like Fen says the 44 psi in the rears will only result in snap oversteer when you get on the limit. Pretty much every tyre I have tried works best with maybe 2 or 3 psi more in the rears but many ppl run the same pressure allround and find that nice and safe.
Diver944
Active member
I think what Neil is saying is: Draw a line in chalk across the tread of the tyre. Go for a short drive. If there is chalk left on the centre of the tread then it is under inflated If there is chalk left on the outside of the tread then it is over inflated If it's all gone then the pressure is perfect (or you drove for too long 
)
)Neil Haughey
New member
That is pretty much it but you don't have to put a chalk line across the whole tread, just the last inch and down onto the top of the sidewall. The basic general rule is that you should be using all of the tread, you will have to drive the car pretty hard on some roundabouts though to scrub the outer edge of the tread. Of course if one uses the same tyre make and model over and over it becomes clear from the wear pattern if the tyre is overinflated or underinflated. I tend to monitor my tyre wear on all my cars this way by just measuring the tread height on the inside middle and outside of the tyre. Also helps for example to monitor if the camber settings are good.
That white S2 with the blue wheels was on PH recently - didn't the owner do a 'round Scotland trip in it sometime late last year? Back to the original topic - FWIW I run 38 all 'round in the D90's on my S2, but they are 16 inch and therefore this isn't terribly helpful! Oli.
Peter Empson
PCGB Member
Too light a colour for me to be honest, but the track cup ones will be cobalt blue when I get around to it [
]Wigeon Incognito
New member
It's Northo's as far as I'm aware. I'm really starting to notice how many people seem to have/have had 944s and MX-5s - I have both at the moment too although my MX-5 will sadly be for sale soon too.
I'm another one who has previously had an MX-5, although technically it was the missus'. Fantastic car, a lot of fun to drive, but a little flimsy and exposed at the end of the day. After a near miss with a couple of lorries on the A46, we decided to get rid, and she has replaced it with an Impreza (what can I say, she's a classy girl!), at about the same time as I got the 944.
I had two MX5s - at the same time. One was a standard UK 1.8 and the other was a Banzai turbo'd 1.6 Eunos import. I might have another one as a cheap way to scratch my annual itch for a convertible, though I really fancy addressing that with a 'Cruiser FJ40 with a Chevy V8 transplant next time. I also had an Impreza, but I don't talk about that - and I'll NEVER have another one of them [:'(][:'(][:'(]
OK, so you hated the Impreza (there must be a story there) ... what did you make of the MK5's? The turbo'd one is surely worth a comment or two! (If I was single, or MX5's slightly larger, I'd have bought one instead of my 944. However SWMBO veto'd the idea on the lack of rear seats and not enough boot space to fit her make up kit in.) Oli.
Oh no, don't get me wrong, I don't hate the Impreza. It's just a little, well, chavvy. It's an 06 WRX with STi brakes and a dump valve, so not as bad as some of the really heavily modded faux rally cars. We actually test drove one where you could barely hear the stereo at full volume over the engine/exhaust noise, kinda fun - but entirely pointless as a daily driver for her to commute in, and would have necessitated the purchase of burbery accessories. The impreza is great to drive, and really very very quick. But the downsides are that its a lairy thing even when you are tired and just want to get home; and of course, every spotty oik in a modded clio wants to race. You'd think they'd learn. The MX-5 we had was the 1.8 UK spec N/A, and was fun. It was pretty skittish at speed on A roads, but loved the twisty stuff around the countryside, and having the top down on a summer's evening was a real joy. We managed always to pack enough kibble into the back for a weekend away, and it was absolutely bulletproof in terms of reliability. Having owned and driven both, I prefer the 944 for its stability at pace, its looks and its cornering (which is a close run thing). I preferred the acceleration on the MX-5 (bear in mind I only have a Lux), and loved the roof. So easy to pop up and down.
The turbo MX5 was full on psycho nutter. It was supposed to have 246bhp, it had an LSD and it was geared as a 1.6 (and braked as one when I got it but I put proper stoppers on it). It would keep up with quite quick stuff to about 90, it's biggest scalp being a Bentley Continental GT on the A43 on the way to Tipec 2006, but the best bit was being able to go sideways pretty much on demand. The Impreza (which was an RB5, so supposedly one of the ones to have) was just rubbish. Panels so thin they would dent if you rested your eyes on them too heavily, the ambience of a 1985 Nissan Bluebird mini-cab with retrofit Alcantara seats and the class of Vicki Pollard. They aren't that fast, the engine sounds like a tractor (which I guess is why they all have massive exhausts to amplify the misfiring-esque exhaust note) and they don't handle, unless you consider massive understeer that changes (reasonaly predictably I guess) to a full turn of opposite lock when the fronts get a bite to be good handling. I don't, especially on the inside of a roundabout on the A303 with an Escort immediately to my left. They also romp through Optimax as it was back then far more enthusiastically than the performance gives them a right to and they are "tough as glass" as someone once put it to me. I could barely get out of mine at under 3 1/2 years old, with extended Subaru warranty and 52,000 miles because it was so high mileage. What I didn't realise was that the dealers all knew it was knackered with that mileage on it - I chopped it against a Seat and got a call then next day saying it had no oil in it (3 days after a main dealer service) and smoked so much when topped up it needed a rebuild. Don't get me started on the dealers either - they made Alfa dealers look competent...
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