Has anyone tried using really wide tyres & rims?
i reckon I could fit 245mm to my rims, just wondering if this would add extra grip to the front or what the drawbacks would be?

Fitting wider tyres doesn't give any more grip at all - its a fallacy

there is only one way to increase grip and that is to change the co-efficient of friction between tyre and road - there's two ways to do this:

1) fit a softer compound tyre or drive on grippier tarmac)
2) increase the weight of the car (or more accurately, the downforce acting on the tyre contact patch

I think the 245's will rub the wheelarch liners as the steering is turned.

My 16VT came with 245's on the back and they just about rubbed the outer part of the arches on rough roads as well.

Thou should'st heed the advice of Nigel.....

having wider tyres will improve grip in some extent ...

And lessen it in another

There are also swings and roundabouts available......

maybe - depends on your definition of 'improve' - however, it certainly won't 'increase'

with wider tyres, you'll get marginally better lateral grip, and for the front tyres at least, the slip angle will be improved. However, you'll find that slides become less progressive and you'll risk snap-oversteer if you fit wider tyres to only the front.

FWIW, I run 215 section tyres, despite my power figures. I have very little problem with traction in the dry, and rarely in the wet either

well i would put wider tyre at the rear too wide up front will get tramlining ...

Wider tyres also mess up your aerodynamics.

Ok thanks for all your advice, the reason im asking is I recently replaced the standard rims with team dynamics 17inch and fitted 215 falcons. the handling was noticeably better than the standard rims and tyres especially on accelleration round a bend. has anyone done a test vs standard 20vt rims? the new rims and tyres weigh approx 1kg heavier than standard.

There are so many variables in this I am not sure what it would prove. Different wheels, tyre widths, tyre make/model and new/used tyres.