Rear tyre grip
 

I'm actually looking for opinions on a fwd car here, but could be interesting.

Situation is a 205Gti set up for gravel but running on tarmac for an upcoming event, We've dropped the ride height a bit but its still on gravel springs and dampers.

Running road legal slicks medium hard compound.

Myself and my co-driver disagree on what to do with the rears, I think keep slick, but he reckons cut to intermediates to get the temperature up in them.

Maybe I'd agree in a tarmac set up, but I think as the car is well balanced and has a tendency to stick the back out anyway a bit temperature shouldnt be a problem. That and although I try to keep it smooth my driving style tends to be on the aggressive side.

What's the opinions here, cut.. or not?

Other things to think about is, we only have 6 tyres, 2 of which will be cut anyway for the event of rain. If we cut the rears that gives 4cut and 2 slicks. Not ideal if we puncture a front and it stays dry.

(hopefully this will spark an interesting topic :) )

Cheers,
Dave

Are you running same size front & back? If so I like the cut rears idea.

The back end only has about 1/2 the weight of the front so to me it doesnt make sense to use the same amount of rubber. I used to run wider tyres at the front of my 205.

What is the gravel setup in terms of springs and arbs?

The rear beam is completely std (as per challenge regs) with gravel dampers, stiffer than std softer than tarmac.

Front is std arb (regs again). The suspension is firm that you can barely move it by pushing on it yet get quite a bit of body roll when really going. So I would say it's over sprung and under damped for tar.

If anything the car oversteers on tar once up to a decent speed. The idea behind cutting it is to warm it further to get more grip at the rear.

Dave

Oh and yes, front and rear are the same size

Whats the front spring rate?

The firmness on the push test could be due to lots of low speed damping. Mine was like that when it had initially been modified by a rally geezer (Autofit) and it was way undersprung and overdamped with 120lb fronts and billies off a sunbeam with 250lb springs.

Have you measured the tyre temps with the slicks?

I don't know the spring rates, but they look like thick coils (2nd hand). I could easily be wrong but I would have thought if it had was over damped it would tend to skip and bounce over rough gravel, It tends toward keeping it's wheels on the ground which is why I'm inclined to suspect the opposite.

Never measured tire temps, by the time you get off stage, through the time controls and find somewhere to stop things have had time to cool off (and there's usually something broke to worry about :) ). I'll give it my best shot next time actually, as that's going to be more accurate than speculating..