Around the Rim (Part 2)

Today's post continues the saga of rotating the rims around the various cars in the yard so we can get rid of the donor ZX we picked up a few weeks ago. This time, I focused on the spacer to get the replacement rims for the MGB (from a mid 90's Honda Accord) to fit.

Space Case

1" spacer added

ET and backspace are kind of confusing topics. To really get it, you first need to imagine the rim and consider that the spot where the rim bolts to the hub is almost never at the centerpoint between the outer and inner edges of the rim. The ET (Einpress Tiefe) is the distance in mm between that centerpoint and the spot where it actually bolts to the hub. This measurement is interesting and important when calculating how well different rims will fit. It gets more complicated as you change the wheel width. I have spent lots of time trying to figure this out (see Wheels, Studs, Chrome and Backspace), deciphering the RAtwell page on tires, and finally building a spreadsheet to help me compare rims and tires. If you have the measurements for your wheel arches, and suspension, you can jump straight into the 1010Tires offset calculator. I've played with that thing quite a bit while trying to figure out what rims I could fit on the old bus. Of course, I didn't discover it until after I'd spent hours building and refining a spreadsheet calculator. Ha! And after all that, I just bought a set of 16" rims from a guy who had them on a Vanagon (See New Shoes), so I didn't have to test my spreadsheet or other measurements in the end.

rear view w/spacer

Anyway, I believe that the ET for the crummy chromes is lower (moving the rim further out) than the stock MGB rim and much lower than the Honda Accord rim. Or the other way: the Honda ET is higher than the MGB rim which is higher than the ZX. Even if we factor in that the Honda rim is an inch wider, the offset/ET is actually a bigger factor in the math, based on the pictures.

I didn't take pictures showing how close to the wheel arch the crummy chrome rims are, but the rubber on the wheel just barely extends out past the outer edge of the arch. In the photo in my last post, you can just make out the front tire and see how it is pretty far out towards the wheel arch. Technically, this isn't legal, but with the way big trucks are allowed to drive around with tires multiple inches out past the wheel arch, I guess the traffic cops have bigger issues to handle. I can support that.

The Honda Accord rims, on the other hand, are pretty recessed into the well when compared to the old crummys. I have at least an inch of space before I'm getting near the wheel arch, and as you could see from the picture on my last post, I couldn't even get my index finger between the rubber and the spring.

Math? Why Math?

spacer on, better fills wheel well

So, after all that figuring, thinking and prior planning I'd done before, you'd think I would use the same cautious approach to solving this need. Nope. Instead, I hit the eBarf and found a set of 1-inch thick aluminum integrated-lug wheel spacers for $85US delivered. My logic:
1) I need a good inch between the rubber and the spring.
2) I have at least an inch between the rubber and the wheel arch.
3) There is nothing in the front suspension, hub nor wheel arch that is more restrictive than the rear spring to rear wheel arch.
So, if I can get a rim into the rear wheel well with one of these spacers and it doesn't rub (and it shouldn't), then we can get all 4 mounted without issue. As you can see from the top picture, there's much more room for the tire on the inside and from the middle picture, it doesn't protrude out past the wheel arch on the outside. Barely. They look right on the car now.

Now that I have proven that they can fit, and look nice in their native state, I'll be spending the next wheel-related post walking through my steps and experiments to clean them up. That's it for today. Its a little short since it's my birthday. Have a great week and as always, thanks for following along-