tonytaylor

Jim,

The throttle body, MAF and air filter were all fitted at the same time and the chip was written on the dyno to take advantage of the changes so I can`t give a comparison of before and after for the throttle body alone.

To be honest the TT brakes were a bit of a disappointment as far as stopping quicker was concerened when I first fitted them. IMHO the C2 master-cylinder is inadequate for the conversion as well and I ended up fitting a 993 unit and servo.
The advantage of the big reds is lack of fade. As far as improving braking is concerned I found the change to MPSC`s made more of a difference, especially with the Pagid pads. Losing some weight also helps.
I haven`t used Pagids with the stock calipers so I can`t compare them to the TT`s with Pagids

forklift

Great thanks.......

DaveK

I used to run 36 all round on my SO2s - until I mentioned it one day and Adrian told me it was dangerous - that 36 all round was good for 17"s but 16s should not be less than 40 at the rear.

I will experiment with the pressures - but all I can say is at the same pressures, the SO2s hold the road much better in wet corners than 712s - at least in my car.

I probably should also have mentioned - I don't have "stock" suspension, I have RUF suspension.

Adrian

Dear Dave,
Dangerous might be a little strong. Unwise simply because if a tyre is under inflated then it runs the possibility of running around the rim which will cause the side wall to collapse causing disturbing movement of the rear end.
I experimented with a whole bunch of tyre pressures with 16 and 17 inch wheels and different tyre pressures and I found below 40 psi on the rear with 225 or 245s there was an uneasy feeling creeping which got worse and worse under heavy load.
I also found this with 17 inch wheels, 205/225 on the front as well when I got down around 32 psi.
However is live in a mountainous area and the roads are colder generally which means "hot" pressures are going to be lower.
Remember all pressures mentioned are measured cold.
Suspension systems, settings and wheel alignment settings also play a significant role as well. Unfortunately in these cases you may be comparing apples and oranges. You need to compare with similar set up cars. Somebody running 2 degrees of negative camber on the front wheel is going to have a totally different experience to somebody running with 0 degrees.
I am running standard ROW C4 wheel alignment setting but at Carrera RS ride height and a sports supension.
Ciao,
Adrian
964C4

DaveK

Adrian,
You replied on Smartgroups to me last year, and told me it was "quite dangerous" to run 36psi on 16" tyres in winter conditions.

Adrian

In winter yes it is but this thread is about summer tyres not winter tyres.
It is extremely dangerous driving with SO2s in winter when the road temp is below 7C or there is snow and ice around, regardless of tyre pressure. However that is not the subject of this thread.
Winter = winter tyres, no SO2s and keep tyre pressures when measured cold, high at the recommended pressures.
Summer = summer tyres, SO2s etc and playing around with tyre pressures.
Ciao,
Adrian
964C4

Phil Raby

I've really pushed the Avon ZZ1s today and, guess what? They're actually quite impressive. I was expecting them to be average but they're performing well in the dry. I'll report again on wet-weather performance

robmug

It may be a continental european difference, but I don't know anyone in the UK who uses winter tyres - and our temperatures rarely rise above 7C!

I would have thought that SO2s can be used all year round, albeit taking into account the prevalent conditions.

Phil Raby

As Rob points out, no one here uses winter tyres.

Are you saying this because the of the risk of ice on the road, or because the characteristics of the rubber change at low temperatures? And why 7C? That sounds a very precise figure?

Cheers

Adrian

Dear Phil,
John and I were only discussing this last night. I have no idea why you guys in the UK do not use winter tyres. Every year before winter we get all the motoring shows showing why you have to change to winter tyres. Porsche send out documents doing the same. If you read my book you will find all this explained with braking graphs etc.
At 7C road surface temperature it has been proven that the rubber gets too hard and will not reach operating temperature.
Again this is a UK issue and needs to be sorted out there. The rest of Northern Europe all use winter tyres with advertising campaigns to make sure you do.
DO NOT drive into Switzerland or Austria in winter without winter tyres. In Switzerland if you have an accident it is an automatic fine regardless of fault or an automatic fine if your auto is controlled and in Austria it is illegal to drive in winter on summer tyres.
I do find this strange however on smartgroups we have discovered that some 964 owners especially in Scotland and Northern England do fit winter tyres.
It is up to you, it is your 964s not mine. I tried a winter on summer tyres and scared the pants off myself, never again.
Ciao,
Adrian
964C4

Phil Raby

Thanks for the explanation, Adrian. Maybe our climate is mild enough for it not be a real issue - it would be interesting to see accident statistics, I'm not aware that we have many more accidents in the winter. Also, at what temperature does it become dangerous to run winter tyres? With our weather we'd be constantly swapping from one to the other!

As regards operating temperature, surely that depends how you drive. Mrs Brady pottering along in her Micra is unlike to get her tyres warm even in the middle of summer, but I'm sure Christer in his 964 has his tyres smoking in the depths of winter.

Adrian

Dear Phil,
When Porsche issue their yearly wheel and tyre summary, testing and recommendations I am sure it is not just for continental Europe.
I am sure nobody in England even investigates accidents anymore from what I have read. Cutting costs.
However as I said it is your decision as an owner but I have learned the hard way that winter tyres are made and used for a reason as have others and we all crashed on the same brand of tyres as well.
Ciao,
Adrian
964C4

PS: The first indication that the road surface is too cold for your tyres is the onset of understeer. More than normal that is if you have a C4 and surprising understeer if you have a C2 or Turbo.

slim_boy_fat

Adrian, one of the primary reasons is that we have quite an involved winter maintenance programme on the road, involving salt gritting and spraying glycol. Carefull weather monitoring and road sensors detect ice. We rarly get much snow in this country (i know you might not agree but its true) So the need for a thinner heave tread tyre is really not there. Driver education is prob more important with people not making unessesary journies i the winter and drivng at slower speed. (this obviously does not always happen)
Hope this helps
Regards

Ruairidh

I agree with all of that but IMHO most of England and large areas of Wales and Scotland just don't have the same degree of winter climate (ice - cold - snow) most years that justify winter tyres.

Interestingly (at least to me) was living in Michigan - which has long and pretty severe winters - I didn't see much sign of folks changing their tires as the seasons changed there either.

Do all countries in Northern Europe have winter tyre programs?

robmug

If summer tyres have a deterioration below 7C, what's the corresponding temperature point for degredation of performance for a winter tyre?