Looking to get a set of wheels. These damn wheels take forever to clean and they get dirty so quickly.

 

Here's a decent thread discussing the bore stats; straight & to the point w/no OT digression :
https://www.northamericanmotoring.co...d.php?t=115823

I haven't had my rims off to measure the backspacing tho. sorry.

 

follow this link:
http://www.mini2.com/forum/faq.php?f...heel_tire_tech

shows the offsets of most MINI wheels. will give you an idea of the back spacing and/or offsets needed for your setup.

MINI hub bore is 56.1mm

 

How do you measure backspacing? Maybe I'll give it a shot today.

Is "ET" considered the backspacing number?

Here what I think the procedure will be...

From the inside of the wheel, take a staightedge across the hub face, then using another ruler running perpendicular to the straightedge, measure the distance to the back side of the spokes at the lowest point?

I found my tool kit so I want to see how it works.

 

You got it. That's exactly what I would do too.

 

Okay, at its deepest part I'm getting 30mm (towards the center of the wheel where the caliper lives), 28mm at the shallowest point (towards the outer part of the wheel). You're gonna be safe with a 30mm backspacing for sure. With the wheel mounted, there's still 5-10MM clearance, maybe more (this is just a guess).

I used a square riding along the hub surface with a digital caliper measuring depth.

 

I said this in another thread, but offset (backspacing) is only part of the equation for wheels for the JCW. The car has VERY LARGE brake calipers, and most wheels that would otherwise fit the car will NOT clear the calipers. You'll need to get a wheel that is KNOWN to fit over the JCW brakes.

Otherwise, you'll be shooting in the dark -- even IF you find a wheel with the right bolt pattern (4x100) and centerbore (56.1mm) and width (7" to 8" wide) and offset (somewhere between 40 and 50mm should do), the spokes of the wheel may run into your brake calipers.

Also, the wheel centerbore does not have to be exactly 56.1. Aftermarket wheels will usually have a bigger bore, so you'll use a centering ring to mount them. You just can't run a SMALLER hub bore...

Conveniently, there's a thread wheels that do fit the JCW that I started, HERE.



--Dan
Mach V

 

Thanks Dan. I saw your thread on the the rims that fit the JCW. But while those wheels are nice, I'm looking at other brands. But yes, I'm trying to find out if the rims I'm interested in will fit over the brake calipers. Every other measurement is within scope.

I cross posted a similar thread in hopes to catch someone who's been down this road before.

NOTE:
My post incorrectly stated backspacing at 30mm. What I measured was NOT considered backspacing. I don't think there is an official name for it.

Maybe I'll OFFICIALLY name it the "brake caliper pocket depth" (distance from the rim's hub mounting surface to the back of the spoke) I can't believe that's not an industry standard.

 

SmokeM, et al, I owe you an apology. While we were all speaking about the right thing -- distance from the spokes to the hub's face -- I'm afraid I recalled how to refer to it incorrectly. I called it backspacing. While I've seen it called different things in different places, Caliper Height (shown here) aka Caliper Depth (or as I read your previous post now, your "brake caliper pocket depth" negates any ambiguity ) is probably the most correct way to refer to it.

This is the best diagram I can find on the web. (note, they don't use "hub bore" here either, but rather "hub pilot diameter")



Sorry for the confusion I introduced into the equation using the incorrect terminology.

 

No worries minim8o! The mass confusion wasn't started by us. As a whole for 99% of the folks out there, the backspacing concept works. For the other 1% that upgrades their brakes (guessing at that percentage), that number is not the answer. I too was under the impression "backspacing" was the number I was looking for.

I took the liberty of updating the diagram with the dimension I think is the missing link (I also cleaned up the hub interface a bit). While you are right that the caliper height is a critical dimension, it is only half of the puzzle. Maybe the people who actually make the wheels call this dimension something. I really can't believe it doesn't have an official name. Anyway, here is the updated diagram to show what we are all after. I hope it catches on so folks like Dan and Krut don't have to spend an afternoon, mounting wheel after wheel to see if it will clear the calipers :(

While we're at it, that dimension should have a min and a max depth. The challenge wheels have a sloping spoke, its not entirely flat, its deeper on one side then the other by a couple of MM. I'm sure other rims are like that as well.

 

I don't mean to quibble, but there is NO single number that's going to tell you if a given wheel will fit over a particular set of brakes. Spoke and lip design are complicated and vary by wheel -- the spokes are rarely flat and square in their inner profile.

Either we're going to need a cardboard template (which will match the profile of a JCW caliper) to set inside a wheel to test the fit, or we're going to have to test fit each wheel candidate on the actual car. Knowing that building my own template is potentially going to give us the wrong answer if I'm off by a mm or two, I have gone with the test-fit method. Time-consuming, but it works...

--Dan
Mach V

 

I'm in agreement Dan. I think we're saying the same thing. My focus was on this particular dimension though, as the other wheel dimension are easily obtainable.

You may also be responding to my original post before I edited it to account for a sloping spoke. We're on the same page though.