confused... help!!! was thinking about getting some 18's for my 03 wrx sti. it's primarily used for track days, what's all this about 18's messing with the cars handling? i'd assumed (possilbly foolishly) that bigger wheels = more grip so she handles better? am i gonna mess her up if i fit the 18's??? help!

 

IMO 17 are better for handling than 18s as you can use a more cushioned tyre and 18 can be a bit lardy compared to 17s, the reaction response is better on 17s too. 18 is more for look IMO. And weight diffrence.
This is all my opinion.

 

On a newage 18's are fine and IMO better than the 17"rim....because of the wider width tyre you can run on a newage, means you can run a higher profile, unlike the classic.

 

I'm sure prodrive used to advise 18" on a newage.
Fitting 18" also allows for bigger brakes

 

For track use i agree with busta 17`s give a far better feel, 18`s are alright for road use but wont feel as good a ride and you will feel the bumps a lot more

 

18s far better on newage-IMO

 

Correct!

18's improve torque delivery. get them.

 

Im with Busta, 17s are better for handling but 18s look better.

 

Also if you are that bothered about 18s having more tread on road, 17s you can get wide tyres of upto 255 width dependant on wheels.

 

is a cushioned tyre a good thing for a trackday car? i'd kinda thought the stiffer the better? oo-er! side wall rigidity n all that (of course i could be barking up the wrong tree here!) would 17's and some lowering work? reduce centre of gravity, body roll etc? i want cornering so awesome my face slides of my head when i go round a bend.

 

On 17s I would use a 40 tyre on track and 45 on road and get the widest possible tyre that you wheel alows (235-255). Thickness also depends on your driving style (racing over the bumps on corners and allowing continuas speed throughout them, or just sticking on Tarmac).
Coilovers would be best idea also if just tracking it instead of lowering springs, roll will be massively reduced along with arbs, drop links etc and a MUST is a full geometry for track will see great gains.