Wheel Spacers - Good/Bad?

[TriShield]

Looking to install GNX fender flares on my 87 GN with the Pontiac GTA style wheels. Are wheel spacers adviseable to push the wheels out just a little bit to fill the flares? What are the drawbacks?

What size tires should I run on the car? Looking to run the same size tire on all four wheels instead of bigger on the back, smaller in the front.

 

[Red Regal T]

I REALLY DON'T KNOW ANYTHING ABOUT HIGH DOLLAR SPACERS. ALL I'LL COMMENT ON IS SLIP-ON SPACERS. YOU CAN BUY THEM AT ANY AUTOPARTS STORE AND ONLY ARE AVAILABLE UP TO 7/16". THEY MAY COME THICKER BUT I'VE NEVER SEEN THEM. AS LONG AS YOU REPLACE YOUR STOCK STUDS WITH 2" LONG STUDS, ALSO AVAILABLE AT AUTO PARTS STORES, THERE IS NO PROBLEM WITH THESE SPACERS. I USE THE 7/16" SPACERS ON MY REAR TIRES. ALSO HAVE ALUMINUM DRUMS WHICH ARE THICKER THAN STEEL.

PROBLEMS ARISE WHEN THE STUD IS TOO SHORT AND THE LUG CAN'T GRAB ENOUGH THREADS. THIS IS DANGEROUS.

AS FAR AS TIRES, I RUN IROC WHEELS WHICH ARE THE SAME SPECS AS THE WHEELS YOU'VE MENTIONED. I RUN 255 50 16S ON THE REAR AND 225 60 16S ON THE FRONT. APPROXIMATELY THE SAME HEIGHT ALL AROUND.