Tyre Pressures

I have a C4 on 18" Sport Design wheels. The recommended pressures are 44 rear and 36 front. Have not experimented previously, but was thinking of reducing the rears. Any thoughts?

Try 36 cold, all four. Melv

Conflicting with my previous advice that 34 front and 36 rear (cold) and keep them under 40 alround (hot) was the best compromise I have to say that lower pressures seem to generate more grip and more predictable slides. At Spa last monday and tuesday I followed Ian Barnsley's advice (Silverline) and reduced the Corsa's to 30 front and 32 rear hot and the grip and controlability were superb. On the road on P Zero Rosa's I use the factory. Hope this helps.

Thanks, Melv, is your recommendation for road or track use - should have sead, I am on P Zero Corsas. Kevin - I see that you keep to the factory recommendation for road use. Spizz

Road -try it! Melv

Just a cautionary tale...... Many many moons ago, a friend rolled his Lotus Cortina, on which he had fitted wider tyres than the stock. He was playing with pressures and lost it. As he was well known to his insurance company they checked out the car and refused to meet his claim due to 'tyres size and pressures outside recommended specification'. Kevin's use of factory settings for road use seems like a sensible approach. Seems like you would need the endorsement of your insurers every time you went out for a blast when pressure playing!!!

Tim, Good point, I have to say I tend to keep my driving style fairly conservative on the road and I'm therefore very comfortable with the performance offfered by the standard factory tyre pressures. In the 70's when used to play with Imps the insurance co's were always keen to measure the capacity of hot looking Imps after if they crashed, its amazing how many were insured as 875cc but turned out to be 998cc, an easy get out for the insurance companies. Regards

When the infamous Mrs C [COHEN NOT COOKE]received a visit from the ins inspector abt 6 months ago [bodywork damage only] car less than 6 months old Audi S3, first thing he did was check the tread depths all round ......................Beware they mean it now adays the rules are the rules !

The sticker on my bonnet says (for 18" wheels) - 36psi Front, 44psi Rear. That's what I think most people run for normal road use.

I agree with Richard, on my 1998 C2 running 18"'s its 36 & 44 or 42. Obviuosly for a track day you should reduce these by a few bar so the temp when hot is of that above. I would imagine that different models and wheel/tyre combinations would have different pressure though.

ok thanks guys mine is running the gt3 sport line alloys so I will go with what you say. maybe 34 at front 40 at rear? just don't want to impact the wear on them

At 34/40psi they will be slightly underinflated, so expect more wear on the outer and inner edges. The tyres often wear more on the inner edges anyway (especially if the camber and tracking are slightly out) so if I were you I'd stick to the factory recommendations.

chaps just checked the car and it was spot on at 36 front and 44 rears. looks like the tyre place I got them from have done a few before ;-) thanks for all your inputs NW

36/44 is correct for your tyres. Some people run them a bit lower, but it will affect wear, handling and fuel consumption accordingly.

...and in the future, no need to look in the book, just see at the back of the fuel flap [ ]

I always forget that, unless I fill with fuel before checking the tyres!

My sticker is on the underside of the bonnet.......

There was an article in Autocar a few years ago when they were running an early 996 and the journalist described the ride, with sport suspension, as unyielding. An unoffical Porsche comment was that it would be OK to run the pressures 4psi lower front and back which would take some of the harshness out of the ride. I tried dropping mine by 4psi all round and it does ease the ride slightly but did not appear to adversely affect the handling. Terry

44psi on the rear wore out the middle of my contis, now use 40psi.

I think that the recommended pressures are just right for road use, too low and it adversly affects handling. Although the centres do wear out first this is to be expected with such wide tyres spending most of the time goinig in a straight line. However plenty of twisty roads evens out the wear better. In fact all my recent tyres have become illegal due to edge wear first. I have had 2 996C4s in the past both with sports suspension and spent most of my fun motoring in theYorkshire Dales, the Scottish Borders (where I live) and the Lake District, none of the roads can be described as smooth, (far from it) and yet the susspension was an excellent balance of refinement and handling. The motoring journo who said it was unyeilding is talking utter c..p, or he is Vectra man and not worthy of commenting on the best sports cars in the world. I would hate to think what he would say about the sports suspension on my 996tt. Iain

Thanks for that ..where in the borders do you stay ,perhaps you could organize a wee run down your way ,there are a few Porsche owners down your way ,come across a Colin Robertson stays St Boswells ?

Hi, Kitchens, I stay in the Thornhill area, D&G, but as I used to reside in The Lake District and there is a great bunch of exteremely sociable car enthusiasts in the Northern Lakes have continued on the Lancs and Cumbria register. Perhaps we could organise a joint trip out meeting up half way somewhere. I will be seeing some of them this weekend so give me an Email ( [email removed] ) to discuss. Iain

Kitchens I take it as you are off line that you are also watching a depressing match[ ] Who would buy an Italian car anyway.

Did you expect any other result [ ]Italy a differant class. I was down your way a couple of weeks ago great road from the M74 over to Thornhill have been down a couple of time to Drumlanrig Castle Next time you are doing a event give us a email and will pass it on to the RO I used to be the RO for the region for 5 years, nice part of the country on the day out went down to Southerness and back up through St Johns of Dalry and up to Ayr and home to E-K . Brian

Seem to have posted this response in the alignment thread too?! But, am sure I read somewhere that the rears can be run at 36 psi.

36 front 44 rear iirc. Some say to drop these pressures a little as the above are really best for tackling autobahns at xxx mph. Dropping mine has resulted in a more forgiving ride, though I haven't dropped them as low as some people. Have a play with your pressures and see what suits you. Have noticed that my rears now wear evenly across the tyre with the lower pressure. In this cold weather the pressures will read lower. HTH.

When I had my 996 with those tyre sizes, I ran them at 32/40 which seemed to provide a good compromise between ride comfort and handling. Terry

I believed they were 36 & 42 which is what I run. I guess there are tolerences to personal preferences, tyres and maybe even suspension set ups ... Which leads me on to a thought Baptistan mentioned about the weather. When tracking your car, its recommened to lower the pressures as a good track session will increase the pressures above normal temperature. Makes the car very skiddy if you dont. However, my question is..... In the lower temperatures we have been experiencing recently, I think it would be wise to check & re-inflate tyres to the correct levels (when I checked mine a few days ago they were a few bar down on normal). Does that make sense?

Thanks for the responses. Much appreciated.

Stick with what is recommended would be my advice. 36psi all round is the correct pressure for 17's, unless you run 225's on the rear, in which case it is 36F/41R. I don't think you would gain anything by lowering the pressures, except perhaps in serious snow. I run standard pressures in mine (albeit different sizes than yours) and it is fine.

ok cheers I just thought id check.