Check this thread for empirical feedback ........
IMPORTANT ADVICE: Don't run spacers! - Brakes & Suspension - Zclub - Australia's Largest Nissan 370Z and Nissan 350Z Forum
Note: there is nothing wrong with a space that is hub-centric and which requires longer studs - ARP do a 75mm long stud which is perfect.
My issue is with "spacers" that are fixed to the hub with the original studs, and the wheel is fixed to the spacer with a second set of studs .... it was this typre of spacer that is the subject of the link.
I have used up to 25mm spacers for my track wheels as I could not get a forged wheel with the right offset. These spacers are hub centric to the hub and centric to the wheel centre bore hole, all fixed to the hub with 75mm ARP studs.
The wheel nuts are thrown away after every 20 changes and the stud threads inspected before each track meet. I;ve lost a wheel "at speed" in my race car and it gains youur attention in the ost immdeiate manner possible.