Front Tyres

[Guest]

My early 944 came with 215 tyres all round from the factory and still has 215' s all round.

Im getting really annoying loss of grip from the front end and know the tyres need replacing. I have been told by a mate to put 205' s on the front as the 215' s will imbalance the car by taking grip away from the back or something.

I notice even the turbo had 205 fron and 225 rear so i guess it would be better to stick thinner wheels on the front.

Any views on this?

 

[944Turbo]

Generally the narrower tyre the less grip, so fitting narrower fronts to a neutral car would tip the balance towards understeer, as would wider rears.

 

[Guest]

My 250bhp Turbo has 225' s on the front and 245' s on the rear, as intended, and the grip is phenominal.
I would stick with 215' s, if that' s what the car was intended to be run on, and maybe change to a different tyre brand, if you' re unhappy with the grip on your current tread pattern.

 

[John Sims]

Grip and all things related are a huge subject - Oh goody[]

Many factors will effect grip and whether a car will understeer or oversteer.

In the first instance tyre performance (from one tyre to the next) in grip (in the dry) is greatly influenced by the contant patch. The more tyre that is in contact with the road, the more it will grip. Obviously there are many other influences like the tread pattern and the compound but this can be taken as a rule of thumb.

Based on the above, the wider the tyre the better the grip. But - the contact patch doesn' t necessarily relate directly to the tyre profile as my 205 Conti' Sports have a greater width than the 225 michellins that were on the previous wheels. Confusing or what?

Relative to the ballance of your car, if it feels like it is washing out at the front, not turning in or understeering you would want to increase the effective grip at the front. Putting less rubber in contact with the road at the front of the car will not help this at all. If anything it will have the inverse effect.

 

[Guest]

Well the car have P6000 on the rear and rubbish H rated Power Racers on the front.

I want to put Dunlop SP9000 on the front as i was told that these are the best tyres in 215/50/15 sizes.

 

[Guest]

Depending on how much tread is left on your rears, why not put P6000' s on the front too and then replace all four with Dunlops, when the Pirelli' s wear out.
Just a thought! []

 

[Guest]

Took the car out over the weekend over the long back roads of the peak district. The car is fine in corners with excellent grip but its figity in a straight line. It was quite a bumpy road with parts you could take off on over the like moorlands and i was travelling at about 95 - 100 (this road is empty and you can see 2 miles ahead).
I have been in other cars at this speed on the same road and wasnt having a fight with the steering, i think it may be the width of the front tryres tramlining or my susp is on the way out any ideas.

 

[wedgepilot]

Part of my drive to work is over bumpy B-roads and my 944 will fidget around just like you describe. I think that' s just because of the way the suspension geometry is. My XR2 does exactly the same, although my old TR7 didn' t. I' m sure there is someone more knowledgable than me who can describe exactly why!

If it was moving around or pulling to one side on a smooth road, I would get the suspension looked at.

 

[Diver944]

Marcus, have you got the new tyres on the front yet?

I had a very nervous front end (with 225' s on 17" wheels) and after renewing the wishbone bushes and having a full geometry setup it was not much better. It turns out it was because the tyres had worn unevenly - nearly bald on the inside edge. New tyres removed the fidgety feeling and most of the tramlining.

 

[Guest]

Waiting to get paid before i put the new tyres on and am still deciding if to put 205 or 215' s on.

I checked the tyres i have and they arnt really that low in tread and they are worn even across the tread.

Maybe im used to my old 924 which seemed fine over the same road and not the same twitching (though it went very light over 100mph)

I am having real bad vibrations over 60mph now and am hoping it the suspension as i want an excuse to lower it and stick koni shocks all round.

I also have creaking from the susp now and again and a mate said it might be the anti roll bar bushes.

 

[tim court]

Number One rule with Tyres - Put the same make/compound on all four corners.

Number Two rule - Check the geometry with a trusted specialist regularly - at least every 12 months - particularly with our so smooth brit roads..... Your friendly Porsche independant dealer should point you in the right direction.

As for the squeaking.... you can sus out quite a bit by getting under the front and having a good look and a good tug...... No - the suspension mounting points you dirty boy! A set of mounting rubbers for roll bar etc. are dirt cheap and easy to do if you are half competant.

Hope that helps.

 

[John Sims]

Put the same make/compound on all four corners.

Tim,

I would agree with your comments regarding the same axle, but I' m not so sure that the same tyres front and back is an issue - provided the level of grip relative to both is ballanced for the car.

i.e. If you have a car which oversteers and wheel spins dramatically, then wider, grippier tyres at the back would help.

Pirelli have different front and back tyres in thier top range anyway.

 

[Mark_Bennett]

Pirelli have different front and back tyres in thier top range anyway.

True, but the reasoning is that the " Direzionale" front tyres have a better water clearing tread, clearing the water out of the way for the " Asimmetrico" rears. This was stated in some litrature from Pirelli on the P Zero Direzionale Front, P Zero Asimmetrico Rear " system" .

The website is less clear.
http://www.pirelli.co.uk/en_GB/tyres/catalog/tyre_category.jhtml?catid=UK_UHP&productid=2070

http://www.pirelli.co.uk/en_GB/tyres/catalog/tyre_category.jhtml?catid=UK_UHP&productid=2064

You can also put Asimmtricos all round.

 

[Guest]

Got the new tyres, went for 205/60/15 Pirelli P6000 as im running 215/60/15 P6000 at the rear anyway. car drives much better, steering is more presise and its grips better thean before.

 

[Guest]

Glad to hear it. Do the front tyres now turn in better than the previous ones?

 

[Guest]

Much Better

 

[Guest]

My car has 215/50/15 Yokohamas all round and I' ve never had any problems. It is twitchy over the bumpy Bs but I thought that was because I' m not used to driving with such wide tyres - my old Honda Concerto was twitchy everywhere, and bouncy with it, and I' ve only had my 944 for a couple of months.

Should we really have narrower tyres on the front?

In case you' re wondering, we have similar driving styles from the sound of it . . .[]

 

[Robbiemeister]

Should we really have narrower tyres on the front?

It depends on the wheel size (width).

I think some 944' s have the same width all round, later cars tend to have wider wheels at the rear.

The info. should be in the drivers handbook. If you haven' t got one I suggest you do as they are full of little bits of useful info. eg. the proper way to get the sunroof open.[]