alistair

I went to the MIRA wet grip facility yesterday and Don Palmer used my car for his demo lap with me and 2 other passengers. As we were going round, Don was making good progress, but kept going on about how cars just shouldn't behave like this and describing the car as absolutely silly . The guys in the back had a V8 Esprit and a TVR and were impressed. He told me I was going to have loads of fun and I was beginning to feel a little smug when he said I would find it really difficult in my car which got me wondering why.

At the end he asked if I had an adjusatble diff to which I said no. I had naively thought he was praising the Scoob (as had the other passengers), but when he told me the car was suffering from terminal oversteer and was one of the most difficult cars he had ever driven at MIRA I was a little taken aback . He then asked if I was running slicks on the rear as the grip was that bad (I actually had more tread on the rear tyres than the front). Don's ability had still allowed him to make good progress whilst hiding a big problem.

The reason - I had SO2s on the front and SO1's on the rear.

I took Dons advice and swapped the tyres over and he went out again. The car had been transformed from an oversteering monster into understeerer (and I run with negative camber on the front.)

I have had the SO2s on the front for most of the year and have only ever had one oversteer event, so I've obviously not been trying hard enough . However, Don tells me that if I lost the back, I would have been very lucky to catch it again. The handling at MIRA is extreme, the surface we used most of the time is like ice, so it really magnifies any problems with set up.

The lesson - Don't mix tyres, it really upsets the balance of the car. If you have to mix tyres, make sure you put the grippy ones on the back, unless you are very capable and confident with oversteer ! The question then is which are the grippy ones ?

[This message has been edited by alistair (edited 06-12-1999).]

[This message has been edited by alistair (edited 06-12-1999).]

strong

Totally agreed.

I've said it before but I'll mention it again..

When I got my UK Scooby secondhand it had P-Zeroes on the front and crappy Continental SportContacts at the rear. It was lethal. I had the car swinging all over the place from oversteer.

I ditched all 4 tyres with 5mm tread left on each for S-02s and now I can press-on safely.

Paul.

alistair

I really couldn't believe the difference swapping the tyres made. I'm now totally convinced that the SO1's are absolute crap and that 4 matching tyres are essential to keep the car safe on or near the limit.

Don also commented that similar problems can be experienced with 2 new tyres and recomended that if you have to change 2, even for the same type, be careful for a while.

SDB

Hi Alistair

One thing I will say is that your car felt lovely in terms of set up.

The tyres were obviously causing massive understeer, but the underlying set-up felt spot on.

I would bet that when you change your tyres, the handling on your car will be an absolute dream.

Cheers

Simon

Chewy

I don't want to get into the debate over which tire is better, because I don't know. I am running SO1 and I think they are pretty good. I was going pretty fast around MIRA about a month ago with my crappy SO1's. So the point I am trying to make is that could this happen because of differnt tire heights. Although they are quoted as being the same height there are always slight variations in height, from different tires and also from different tread heights. Now with the center diff trying to give the same power front and rear, now through in a different tire height and you could have oversteer or understeer depending on were the tires are located.
No I probably don't know what I am talking about.
chewy

RichB

Alistair, you are soo right! When my STI arrived I had to put 2 new front tyres on it, SO2s, I have been gradually getting used to AWD and 270+bhp but had found myself 'losing' the back end round small bends when the roads were wet and going very slowly. Having read about the Scoobs wet weather domination I was beginning to wonder what I was doing wrong, afterall 30mph round a roundabout following other cars should not see me twitching at the back, I wasn't backing off or anything. I was becoming more and more of a big girls blouse until I went to get my geometry checked out, I was going to swap the front tyres to the back to see if it made much difference. Bloke says you need 2 new tyres on the back - Uh? They don't seem that bad but sure enough 2 new SO2s later I can't get the back out at all. Expensive lesson but at least I am not afraid of Mrs Brady (old lady) having me round the outside of roundabouts anymore.
Does anyone know where I can get some part worn SO2s from with about 3mm left on them? I guess the old tyres would be ideal for MIRA or a first track day.
RichB

Bajie

Due to an argument with a rather large pot hole I've just put Michelin Pilots on the front but still have Yoko A520s on the back.
Should I change these also to Pilots then.
Bye bye Xmas bonus !!!

Bajie

Just re-read the thread!
Bye bye Xmas bonus

Paul Wilson

RichB, mmm twilight zone, I had exactly the same thing 2 new SO2's on an STi, but I managed to spin it outside my house ooh embarasing! luckily no damage done

DBarthorpe

Are SO1s the tyres that are supplied on the UK car from new? Are they Bridgestone Potenzas?

I assume SO2s are the Bridgestone Pole Positions?

Dave.

alistair

Jap cars have SO1's, UK cars have RE010's as standard. My SO2's were PP's, but I think they also do a standard SO2.

All are Bridgestone.

alistair

Jap cars have SO1's, UK cars have RE010's as standard. My SO2's were PP's, but I think they also do a standard SO2.

All are Bridgestone.