Obsessing on Wheels and Tires

I continue to struggle with the idea of maximizing performance.  It is getting silly.  For example, since the car needs new tires, and the wheels need to be refinished, I'm tempted to get new tires and wheels that yield the widest possible tread width that will fit.  Sounds reasonable, right?  So, what are the constraints?

The first question going down this "big rubber" path has to do with the rear fender skirts.  Here's a comparison of cars without and with skirts:

"Hot Rod" without fender skirts.

"Classic" with skirts.  The "wide whites" are pretty cool!

The difference may seem subtle, but I think the car looks somehow incomplete without the skirts.  I would like to be ABLE to put them on.

Why is this important?  Well, in pursuit of "big rubber", the skirts are the limiting factor for determining how wide a tire can fit.  Let's ignore the wheels for a minute... with the skirts on the rear, there seems to be plenty of room for a tire with 9" section (225 series).  This is about an inch wider (15%) than stock.  Here are some pictures showing the rear clearance with 215/65R15 tires (slightly wider and shorter than the "stock" 205/70R15's) on the original 15x5" wheels.  There is clearly room for another inch of rubber on the inside, leaving a fairly generous 3/4" clearance.

Left rear: 7/8" clearance under the fender skirt

Right rear: about 3/4" clearance

Left rear: 1 3/4" clearance to the rear spring.  A 1" wider tire would fit here.

Left rear: about the same.  The side-to-side consistency gives me confidence that body and frame are straight.

Another inch is good, right? Well, if I leave the skirts off, I might just be able to squeeze yet another inch (245 series)...if I had the right wheel.  Am I willing to give up that inch to be able to use fender skirts?  Well, yes I am.  Am I absolutely sure the 225's will fit under the skirts?  No, not completely.  How far am I willing to go to find out?

Let's talk about wheels.  There are 4 key parameters here: lug spacing, diameter, width, and backspacing.  The stock wheels have 5x4.5" lugs and are 15" diameter, 5" wide, with 3.25" backspacing.    225 series tires require at least 6.5" wide wheels, and 7" would be better.  Backspacing is a science into itself, but there is a lot of info on the off-roading forums... I guess Jeep drivers like wide tires as much as I do!  In any event, the maximum backspacing I need is 3.50"... any more, and the tire/wheel won't fit in front. The inside will rub on the suspension.  In back, I need enough backspacing to keep the outer edge of the tire away from the skirt, yet keep the inner edge of the tire away from the rear leaf spring. For a 225 series tire on a 7" rim, I calculate this to be at least 4.25" backspacing.  This puts all the additional width on the inside, and keeps the outer face of the rim in about the same location. 

These requirements are incompatible!  What do do?  Different wheels front and back?  Once again, the off-roaders have an answer.  Get a set of 4 big-backspace wheels, and then use wheel spacers on the front hubs to keep them from rubbing.

These spacers bolt onto the regular lugs, and the wheel then bolts on to them.

These are available in just about any size. Now, what about diameter?  I'd like to keep the overall diameter of the tire about the same as stock.  Modern tires tend to be smaller, but they would look funny on the t-bird, and would change the gear ratio... the engine would have to rev higher on the freeway, and the speedometer would be high.  Let's keep the overall diameter the same.  But, I can get larger diameter wheels (say 16") and lower profile tires, and end up with the same overall diameter.  This will give more responsive handling.  If, however, I ever want white sidewalls, the smaller wheel is better because it provides more room for the sidewall.  Besides, it looks more "stock", and balanced with the rest of the car.

So, I need 16x7  or15x7 wheels with at least 4.25" backspacing.  Oh, by the way, I'm cheap and I don't want to drop $800-1000 on a set of new rims, at least not until I'm absolutely sure they will fit properly.  I want to get something really cheap just to try this out and check that they fit.  Are there any "stock" steel wheels that meet this criteria, that I might pick up from in a junk yard, yet still look decent?

Well, it turns out that there are a couple... Pre-'07 Jeep wheels have the right lug spacing, and 5.25" backspacing. I can easily pick up a set of 2" wheel spacers for the front, and thinner spacers for in back. 

 

93-01 Jeep TJ 15x7 wheels look nice!

02-06 Jeep Liberty 16x7 aren't quite as attractive

2002-09 Mustang 16x7 wheels have 4.25" backspacing.

These are 2006 16x7 Mustang OEM steel wheels, which you rarely see.  I like the design.  They would look good in body color, with "spider" or bullet center caps!

This is the typical '05-09 Mustang 16x7 alloy wheel.  These are readily available, but a little too modern for my taste.

Vintage Mustang wheels are available in 15x7, with 4.25" backspacing.  Unfortunately, these are highly desirable used, and rather expensive!

Some early T-bird owners really like these wheels.  So do Mustang owners... so they are pretty expensive!

I currently have my eyes peeled for a cheap set of Jeep or Mustang wheels to try out.  Am I obsessing?  Yeah.  Another inch of tread on the road doesn't really matter that much. This T-birds was never intended to be an ultimate performance car, and to try to make it into one is both delusional and futile.  But it is a fun problem to think about.  These wider tires could make the car more unique, more personal, more "mine". 

Then again, maybe it's just a phase I need to work through.

Update 3/28/12:  I made a commitment to refurb the stock wheels, based on Uncle Packard's offer to buy me wide whitewalls.  Yet, I still struggle with wanting "different" wheels!  This makes no sense... the tires won't be much bigger or better with different wheels, it will just look more "custom".  Maybe this harkens back to my boyhood, and lusting after the '57 T-bird down the street with nice AR rims.  

Today I was on the verge of buying a set of Jeep rims for $50 on craigslist, thinking that it would be OK to have two complete sets of wheels and tires... one of which would require spacers.  I could store them in the garage, and fix them up later... I was deliberately ignoring the cost of additional tires and spacers, as well as the lack of space in my garage!  Clearly, other parts of the restoration are more important.

I really need to let go of this... in order to do that, I may need to look a little deeper within, humble myself, and simply accept the grace being offered to me.