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for a 370 Z I do have a set of 17x9.5's but I guess that any response here will be negative on those. Without anything more than a little bit of fender clearance what size would be best, keeping diameter down to max 18". No big horsepower envisaged but the suspension will be set up grip appropriate.

 

Searched elsewhere and found info indicating that 9.5's would be fine using18's but I have 17's so if suitable tyres are available to me they will be used. Search and ye shall find at this grate sight.

 

You have a 370Z, which came with minimum 18's. Why would you even consider using 17's? If money is the reason, sell the car, buy something cheaper. 18x9.5" square or 19x9.5. The Nismo came with 19x9.5 F and 19x10.5 R, but you want a square setup. IMO, the 18's, with the taller sidewall would be better for daily driving use. Smoother ride and less chance of a road hazard blowout. Plus 18" rims are cheaper and the tire replacement every year or two is cheaper.

 

It's for race use so my preference is the smallest diameter that will clear the brakes and for which suitable tyres are available. Lighter, lower final drive and cheaper but if I'm missing something then please enlighten me.

 

Oh. Just saw the screen name. Cute. I'd go 17x10.5 for track use as long as they clear the brakes.

 

Does said Z34 have the Akebonos (or will have those or other) BBK? Would be curious to see if 17" wheels clear them because while not "huge" per se, the Sport/Nismo brakes are shaped in a way that you really need that extra bit of barrel clearance. Guess since you have the wheels, try them out. Width at 9.5" is OK but Z34 can clear a wider wheel with proper offset (big in front, "normal" at rear, like 47/30 or so on 9.5s).

 

I seriously doubt Akebonos will clear 17s. And even if they do if your calipers are within a hair-width of the wheel barrel two things will happen. One, once everything gets hot and expands it might start to rub and B, your calipers and inside of the wheel will be absolutely covered with melted rubber picked up of the track pavement and then lodged into the gap. Speaking from experience, my track Audi had 17s with bbk that barely cleared and it was a mess to clean up after each event.

Also, while there is some weight advantage of smaller diameter wheels, there is also increased sidewall flex that could very well negate any performance advantage you gain.

 

akebono will not clear 17's. Id go 18 10.5 square. thats what im running and its really good, id assume its the same on 370