Re: GT Decisions
I have a jtd on 18's, love the diesel economy and performance, and can't say that the 18's make the ride any more harsh than the 17's. Test drove both rim sizes ansd was not able to tell them apart. Genrerally think that the GT rides very well.
A word of caution about the 18's thought, the design of the rim means that the alloy sticks out further than the tyre making is extreemly easy to ruin a rim just by getting a little too close to a curb eg. pulling up outside your house. The first thing you hear is the bang of the rim hitting the curb, and not the usual squeek of the tyre touching first. Its a bit like going back to a car with wheel trims !!, except it's £300 for a new rim and not £10 for a new trim!!.
I have had to have one rim reconditioned, and was able to get a spare alloy from Ned at Autolusso, so have always got the option of fitting a rim while getting another one fixed.
One other thing about 18's, you don't get a space saver Spare, (I have one now, thanks again Ned), just a compressor and a can of goo, as I understand it you do get a spare with 17's.
I will stick with the 18's though as they look great on the car, I just make sure I use my nearside mirror to make sure I'm not too close !!.