Hose Coupling size question.

I need to get new hose couplings for my greddy 24 FMIC. If the actual pipe diameter is 2.25in should i get the 2.25 or 2.5 couplings for it.

If I am understanding what it is you are looking for, you need to add the pipe size plus double the coupler wall thickness. For example, a 2.5" pipe with a coupler with 1/4" thickness would require a clamp that can do 3" and a little under. In Tbolt terms, you would want one with a minimum size of about 2.75 inches or so. But for T-bolt clamps, which are the only clamps I would ever recomend for IC piping, you can just walk into any NAPA and try them all on for size. They have them in one of thier catalogs, and usually have plenty of all sizes in stock. I just bought 6 or so for the 2g. All of the clamps on the pimped out 3.5" UICP were from the same place, all in stock.

Edit> Reading your post again it sounds like you are asking about the actual couplers. Couplers are measured in ID (inside diameter) and the pipes should be measured in OD (outside diameter). So a 2.25" pipe would require 2.25" couplers. I've used the cheaper thin couplers available from most vendors with good success, but after using samco couplers I dont think I will ever go back. They are 1/4 inch thick, so buy clamps accordingly. www.sporthoses.com is the importer I use.

Hopefully one of those paragraphs answeres your question. :)

that answerd everything, thankyou very much.