I’ve been all over this with the on line experts and the fact remains bigger is better if you have the power to use them…
There is no way larger front tires can cause understeer…
Too wide in the rear causing oversteer? Who is telling you this stuff and what Lotus have they tested their “theroy” on ?
It is good that the world has people who use physics to really push what can be achieved.
But it still isn’t possible to break the laws of physics…
I am simply saying that it is possible to go too big. Nothing more.
A simple equation.
A fixed given weight over a given contact patch/area give’s say ‘x’ amount of downward pressure on said contact patch.
Increasing the contact patch/area but not the weight will reduce the downward pressure as it is spread over a greater area.
Continue increasing the contact patch/area and there will come a point when the downward pressure is so low that any sideways movement will cause the contact patch not to grip as well as it did before.
As I mentioned before it is possible to dial out most if not all of this with softer compound tyres and a more aggressive Geo.
But there still comes a point when grip will be lost.
The possible overly aggressive Geo will destroy the tyres in a very short period of time and become dangerous (but they will give an amazing amount of grip before hand).
All things to be considered when modifying 
I agree with Andy. A cold tyre does not grip as well as a warm one, and if you cant warm the tyre up, through driving style, geo or the fact that it is too wide, then the grip will be less than with a tyre at optimum temperature.
I remember from a Galaxy, a long time ago…
P = F/A
look at the problems with F1 teams, if a car isn’t that hard on it’s tyres then they have trouble getting and keeping them warm for qualifying, in some ways as much of a problem as being too hard on them and having to replace them.
Sometimes I think Frank can be a little too “American” where bigger must be better regardless
Tyre temps and any form of slippery surface will change the dynamic even more…
Thats where I would start to doubt about overly large tyres on a lightweight car … some rain and your stuffed, standing water and poor road surface and your dead.
It gets even more complicated when aero downforce packages and ground effects come in to it… ask any F1 team… 
Just not sure why you would just guess and put wide rubber on the car to fill the arches when all the research & development for the GT3 has already been done for you , I’m sure if you ask the right people they will tell you .
Back in the early 90s I changed the wheels and tyres on my CRX for slightly wider ones , the end result was rubbish , it changed the whole dynamics of the car and was far better as standard .
Guys one thing I think as petrol heads we are all forgetting.
WIDE TYRES LOOK FOOOOOOKIN COOL!!! 
Had 2 friends with E46 M3s at the same time, other than one been vommit coloured, the other one had the optional 19" wheels. I might have looked better but the ride quality was terrible and it also handled worse.
When pushing serious horsepower, wider tyres may well be needed.
How much wider is a grey art depending on a whole load of things. Vehicle set up, body mods, all sorts.
The GT3 might have been restricted in it’s tyre size due to any race regulations it had to comply too. So people now pushing more horsepower than the GT3 without regulation can go explore…
A basic saying is ‘how fast can you afford to go?’.
So depending on how much money you want to throw at wheels/tyres and the swift or not so swift need to replace the rubber. Will be another factor in determining what to go for.
Outright performance costs… 
[quote=SeanB]Guys one thing I think as petrol heads we are all forgetting.
WIDE TYRES LOOK FOOOOOOKIN COOL!!! [/quote]
This ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[quote=SeanB]Guys one thing I think as petrol heads we are all forgetting.
WIDE TYRES LOOK FOOOOOOKIN COOL!!! [/quote]
Oh yes, I remeber looking under the back of a Countach and nearly having a personal accident due to the size of the rear tyres
[quote=SeanB]Guys one thing I think as petrol heads we are all forgetting.
WIDE TYRES LOOK FOOOOOOKIN COOL!!! [/quote]
True , I kept the wheels on because they looked cool .
I still think the proper fit GT3 rubber looks cool 
It would probably work as well
[quote=Muu]Panama Cigars - Carlos Fandango Wheels - YouTube [/quote]
Carlos Fandango , awesome !
Anytime one of you guys wanna bring your skinny assed Exige over and do some canyon runs or some track time we’ll see who’s right…
I hope ya like lookin at my ass…
:whistle:
Just not sure it’s going to handle like a GT3 by bolting huge Flintstones on Frank , is it really that easy ?
[quote=frank]Anytime one of you guys wanna bring your skinny assed Exige over and do some canyon runs or some track time we’ll see who’s right…
I hope ya like lookin at my ass…
:whistle: [/quote]
Get a proffesional race driver to do back to back test for apex speed in yours a 2-11 and an Exige, this will tell you if you are right or made a plonker of yourself and added too much rubber