Geometry and interface
Request rim diameter and width in inches, pitch circle diameter (PCD), wheel offset (ET) and center bore in millimeters, and the fastener-seat profile. Compare caliper envelope drawings at the same hub mounting plane.
Digital sourcing / Spec desk
Black Rhino Sourcing Lab
Build a fitment record that links the vehicle, wheel geometry, supplier quote and evidence to one revision.
Specification matrix
Evidence before commitment
Keep the source of each field next to its value. A supplier dimension, a third-party measurement and a buyer approval answer different questions.
Sample baseline
Record the vehicle, axle, tire size and wheel part revision. Mark the rim datum, whether the tire is mounted and the fixture used before asking for radial runout or lateral runout values.
Load and report scope
Ask for a report that names the tested wheel design, load rating, size, offset and method. Have the importer confirm market applicability and any differences between the test unit and quoted part.
Quote normalization
Compare stock and custom programs by separating stock confirmation, mold or blank cost, sample charges and quote validity. Request the same quantity, finish and named delivery point from each supplier.
Cross-reference record
When the project also includes hub assemblies, match the OE cross reference against vehicle and axle. Confirm hub flange geometry, ABS encoder orientation and included installation hardware before using a cross number.
Release decision
Document any approved substitute and its scope. Reopen approval if a changed width, offset, finish system or production location affects the fitment or supporting evidence.
Worked example / Illustrative
How an offset discrepancy changes the RFQ
Suppose an example brief calls for an 18 × 9 in wheel at ET20, and a quote offers the same width at ET35. This example illustrates a document check. It represents no stock or test result.
Clarify
Hold rim width constant. The 15 mm offset increase moves the wheel centerline inward by 15 mm relative to the hub face.
Compare
Ask both suppliers for cross sections and brake envelopes at the same mounting datum. Do not compare profile photos as clearance evidence.
Verify
Use a representative wheel and vehicle to check clearance through steering and suspension travel, with the intended tire and hardware.
Coordinate
Carry the approved ET, finish and drawing revision into the order and carton checklist. Request buyer approval before any substitution.