BIG BRAKE WHEEL CLEARANCE
Wheel clearance is one of the most commonly misunderstood parts of installing a big brake conversion.
A larger multi-piston caliper can extend further towards the wheel spokes than the original braking system. This means a wheel may have the correct diameter and offset yet still contact the caliper because of its spoke profile.
A correctly sized wheel spacer can provide additional clearance by moving the wheel outward from the hub.
The amount required depends on the wheel design, offset, spoke profile and brake package. Two wheels with apparently identical specifications can provide completely different caliper clearance.