I wondered if this topic ever came up before ?
There seems to be a better choice in tyres with a 50% profile than 45% in 235width for 18" wheels. (fit lots of BMW's and Audi's)
Needing new tyres because my Conti Sport Contact 2's were well worn and winter is on it's way, I've tried fitting a set of 235/50 x 18's on my 159 Lusso. on the front are Dunlop 3D winter tyres and Pirelli Sottozero winter tyres at the rear
Differences from 45% profiles are that the speedo is now perfectly accurate, and at 2000rpm in 6th gear I'm running at 71mph, so I'm hoping I'll be better off in terms of fuel economy.
Acceleration *must* be different, according to the laws of physics at least, but I honestly haven't noticed.
Differentiating between ride and handling....the ride is slightly better, but not sure yet if that is to do with just fitting newer tyres with more tread. Handling doesn't feel any worse and to be honest steering response is very sharp and there is no tramlining like I had with the Conti's with 2mm tread.
They also fill the arches a bit more, which I like. I think the rear wing liner has rubbed the nearside tyre slightly after going over a badly marked speedbump forced the wheel high into the arch, but nothing ont he drivers side so I think I've got away with fitting the larger size.
If you're an officionado on tyres, I've probably gone a gnat's **** over the '3% rule', but i don't think I'll get brake failure
, on Flickr
<a href="http://www.flickr.com/photos/28496053@N04/8063749206/" title="alfa1 by fixitsan2, on Flickr"><img src="http://farm9.staticflickr.com/8458/8063749206_782f3af93e.jpg" width="464" height="312" alt="alfa1"></a>