Every fitment issue we see in wholesale orders traces back to one skipped step: measuring the pipe's outer diameter (OD), not the inner. Here is the two-minute method we recommend to retail customers and wholesale buyers alike.
Measure OD, not ID
The tip's inlet slides over the pipe, so the pipe's OD must equal the tip's inlet size. Measure with calipers across the pipe mouth, or wrap a tape measure around the pipe and divide the circumference by 3.14.
mm ↔ inch conversion table (ER Performance inlet range)
- 51mm = 2.01" | 54mm = 2.13" | 57mm = 2.24" | 60mm = 2.36"
- 63mm = 2.48" | 67mm = 2.64" | 70mm = 2.76" | 73mm = 2.87"
- 76mm = 2.99" | 80mm = 3.15"
Common outlets: 76mm = 2.99" | 89mm = 3.50" | 101mm = 3.98" | 114mm = 4.49".
Slip-fit vs weld-on
Clamp-on (slip-fit) tips need 2–3" of straight, rust-free pipe to grip. Weld-edge tips require professional welding but give a seamless OEM+ finish. Each ER Performance product page lists its inlet options, outlet size, length and installation method.
Between sizes?
Use an adapter/reducer pipe, or ask us — as the factory we can quote custom inlet sizes for OEM/ODM orders via the wholesale program. More fitment answers in our FAQ.
