ARRON BIRD

Having had the geometry changed on my P1 I now want to know the best tyre pressure to use as there seems to be a big difference in the handbook.
I am normally on my own in the car and I like to get on with it!
I`ve also got a set of P7000 215/40/17 of a racing Puma, will the slightly wider tyre give me a bit less understeer as despite the geom changes the car still understeers.
Will tyre pressures reduce the understeer or do I have to buy SO-2`s and if so 215/40`s as opposed to 205/45 bicycle tyres!
Any help greatly recieved.
Regards,Arron.

johnfelstead

Hi Arron, i think the SO2's are superb, they transformed my impreza.

Tyre size is down to personal choice, the 40 profile will flex less which on rough roads will give less grip yet on smooth with give more.

The choice may be down to the type of roads you use the most i think, i would go 45 myself but thats just my preference.

I run 32psi rear, 34psi front cold on 205/50/16 SO2's.

Fosters

I've got prodrive 17s on mine with pzeros (PDEP too).

I've tried lots of pressures but always seem to come back to 33 front/32 rear.

Pzeros sometimes feel a bit slippy though. Someone want to volunteer to take me out in their car with S0-2s on?

ARRON BIRD

Thanks Mike I`ll try 32 front and rear.
I got the P7000 for nowt so I`ll give them a try and then probably go for SO-2.
BUT am I better off with 205/45 or 215/40?

[This message has been edited by ARRON BIRD (edited 03 October 2000).]

MikeWood

Aaron

The P7000s will not be as good as the PZeros. We tried this a long time ago and they felt nowhere near as precise and stable.

Tyre pressures should be 32F & R.

Mike

Josh L

Mike,

On the same thread, I am a bit bemused at to the pressures on my P1.

I have lived in Milton Keynes for some time (no jokes please!) and have always been advised to increase the pressure on my fronts to compensate for the uneven wear caused by all the *'%!ing roundabouts. On my MY98 I ran them at 35 to try to eliminate the excess wear on the insides, to great effect. However it did effect the handling in other ways.

I'm still running in the P1 so I've not had a chance to test the handling properly yet, but I'm trying to achieve a balance between grip and uneven wear.

I've never run 17"'s before so any advice would be greatly apreciated.

Cheers

Josh

MikeWood

Josh

Try 32 as a starting point, but I think you'll find it's fairly close at that.

Mike

Josh L

Many thanks Mike.

Josh

MikeWood

Aaron

You don't have a great deal of choice in sizes as the P7000 and S02 are not available in 205/45ZR17.

Mike

P1 WR

P1 is not understeering i think ,because it has the geometry settings of prodrive and suspension on it is awesome

ARRON BIRD

Mike, have you tried 215/40`s on the 17" wheels?
do they fit?
I fitted P 6000 on my old 17" wheels and I think it improved the grip.
I actually think they gripped better than P-ZERO`s and I fitted some Goodyear F1`s after the Pirelli`s and they seemed better than the P-ZERO`s aswell. I guess what I`m trying to say is I dont believe the P-ZERO`s are the best tryes out there.
Do you use them because of your WRC commitments?
If you did`nt work where you did what would you fit?

[This message has been edited by ARRON BIRD (edited 03 October 2000).]

[This message has been edited by ARRON BIRD (edited 03 October 2000).]

RussP

Good to hear that 32 psi is about right on these tyres. My Sti came with 215/40 x 18 P6000's on it and pressures set at 40psi! Dangerous? Nearly threw it off the road at the first corner i came across! I reduced and reduced til 32psi seemed much better.

Having said which....

The P6000 has proved woefully inadequate for a car like this, the fronts were pretty much shot within 7500 miles. After the damage to the car, I'm letting them reset the geometry to a more parallel setting on the fronts to hopefully stop the scrubbing. Its currenlty 3mm toe OUT on the front, no wonder it pushes and kills tyres!

How much better are P7000's? SO2's really do sound the way to go.

DocJock

Arron, 215 / 40 SO2's do fit on 17"s

IMHO SO2s are well worth the little bit extra

DJ

MikeWood

Aaron

Yes a 215/40 17 will fit, but the ride will be worse and it may suffer from more tramlining.

The fact that we use Pirelli in the WRC has minimal effect on what we use for our road car conversions. Performance is much more important.
During P1 development we tried various different tyres including S02 and found that the Pzero gave the best characteristics.

If I didn't work at Prodrive, my car would be fitted with PZeros. If they are good enough for Lotus, Ferrari, Porsche etc then they can't be too bad although it very much depends on how the car has been engineered in the first place.

A long time ago I used to think that Goodyear NCT's were dangerous in the wet based on experience with a car I used to have, until I drove an Excel at Lotus and it was brilliant in the wet because the car was set up to use that tyre. If you put anything else on it was worse!

Same applied to the first Escort RS Turbos. OK on MXVs but dangerous on virtually anything else.

Mike

ARRON BIRD

Thanks Mike, tramlining isnt really a problem for me i`m more interested in more front end grip so i`m still not too sure.
Oh well thanks for taking the time out to reply.