Originally Posted by roycemek
Not sure if they are slightly different but the calipers are STR-60. From what I understand they are lightened versions of the ST-60. I've been running spacers for a few years now for my track setup so I'm pretty comfortable with them. With the shape of the inner barrels of the OEM 18's the calipers clear nicely at about 6-7mm or ~0.25" and that is at its closest which really is just one particular allen bolt. If I wanted more clearance I could replace that one allen with a half head height allen and gain another couple mm's.
I looked on ST's website for an STR-60 template to compare the minimum diamter required for the ST-60 and STR-60. Didn't find anything. I wanted to see if the STR-60 has some material along the top of the caliper machined off since it seems to require 4-5mm less than the ST-60.