I'm looking to get new rims. How does a 16x8.5 rim ride compared to a 15x8.5 rim on a 240z.

Car has coilovers and flares so clearance is not a problem..

If everything else is equal, a larger diameter, and therefore lower profile tire rides harsher than a taller profile tire. Of course, everything else is rarely truly equal...

GrassRoots Motorsports Magazine also did some comparisons, and noted larger diameter wheels "could" add weight, so if you're autocrossing etc. it might be a factor to consider. I can't remember which issue, but I think it was in the last year.

GWGarrard

The other question to ask is what tires are available in 15 vs 16-inch sizes.

I'm was running Pole Postion -03s but they don't make them in 245X45X16 anymore, they are(were) expensive and I will be running on a set of Yokohoma Es-100s this year instead.

Harshness is relative to tire pressure, tire type and size, road condition, springs and shock settings. This year along with the new tires I'll be riding on 250F/275-R springs and Tokico HTS 16-position adjustable shocks, and TechnoToyTuning TC rods @ -2 camber and 5 degrees of caster. I imagine it will be harsh,

I have I believe 250F 275 R springs with Tokiko's so I'm not that concerned.

I'm curious as to how heavy the stearing is and is it more enjoyable on the street with 15's or 16's?

I looked around and they are making very few 245' and 225 tires;-( in either size.

I have my 16x10 for the track etc and they are really heavy and too much rim for the street IMHO on 275 45 16