what is the measurement called that determines if your brake caliper will fit within the rim?

I know what offset is.

I know what backspacing is but this is the distance from the hub face to the inner lip of the rim. But how does this number tell me if my brake caliper will fit? I think the depth from the hub face to the backside of a spoke is the distance I need. Am I missing something?

 

I don't think that there is a definition of that. What you need to know is the outside diameter (OD) of your rotor, measured through the center, to the top of your caliper. You would then need to know the inside diameter (ID) of the wheel that interests you.

Generally speaking, if you have a R56 with the sport package, (or was it sport suspension?) you have to use rims that are at least 16". That is the same brake kit as the R50/53 JCW brakes. If you have a R50/53 with the JCW brakes, the same applies. I hope this helps!

 

Wilwood calls it "Inside Wheel Profile"- Check out page 3 in the PDF below:

http://www.wilwood.com/PDF/ds492.pdf

-Brett

 

Sure this is one dimension that must be taken into consideration BUT the critical dimension for me is the measurement of the pocket behind the spokes. Too shallow then the caliper face hits the back of the rim's spokes (or face). My JCW already came with 17"s so I know that a 17" rim should fit.

I can't believe we can put a man on the moon but we don't have a standard measurement that will help me determine if my caliper will fit the rim.

 

I call it "caliper overhang". The amount of caliper body protruding above the flush surface of the rotor hat face.

Shown here being roughly .950" or 24mm at a given radius.

 

Tirerack calls it X factor - same measurment!

Alex

 

This is posted for every wheel on the website?

 

No its not. Call/ email me if you have a question on a specific wheel. We can check clearances for you - we have alot of kits on file for this process.

Alex