I also noticed that the inner fender lip was bent at about the 10 o'clock position. Apparently, the tire had contacted the lip, bending it and slicing the tire. I tried bending it back but mostly all I accomplished was chipping the paint. Just to compound the issue, the front tires also rub occasionally when going over seemingly small bumps. Obviously, buying new tires wasn't going to be that easy.
It's easy to see right away why the tires rub--they are flush with the outer edge of the fender. I'll have to say it looks pretty badass, but it's not very practical. The tires and wheels are different sizes front and rear so they'll require a different approach. The front should be the easier to fix so let's start there. The wheel is an American Racing Wheel Torq Thrust D in size 15x4.5". That pretty narrow, but I guess a previous owner was going old school with skinnies up front and fatties in the rear. While I normally like the fattest tires possible on all four corners, the manly steering option necessitates less friction when turning the wheel. Most of the problem lies with the tire which is a 205/60R15. It bulges much wider than the rim. In fact, Google tells me that this size tire requires a 5.5" wide rim at a minimum. So a simple solution is to switch to the proper sized tire for the rim which would be about an inch narrower. But splitting the difference would only move the edge of the tire inboard 1/2". This may be enough, it's hard to say.
The rear fix is going to be a bigger issue. First of all, the tire is 255/60R15. They look nice and meaty from the rear, but Google tells me nobody runs a tire this big on a 65/66 Mustang without performing some sheet metal surgery. The largest anyone fits is a 225/60R15. A simple tire calculation shows that my tire is 27" tall and 10" wide whereas the smaller tire is only 26.1" tall and 9.3" wide. So not only would my already high cruising rpms increase, I'd only move the outside edge of the tire by 0.35" which is nowhere near enough. What gives? It turns out the proper wheel to use is 15x8" with a 4.5" backspacing. But my wheel is 15x8.5" with a 3.77" backspacing. So my 1/2" wider wheel with its smaller backspacing actually sticks out 1.23" farther than the 15x8" rim. Now that is why my tire is rubbing. If I look under the rear of the car there is about an inch of clearance between the tire and the leaf spring--space that I could use on the outside.
After much debate I finally decided to order two new wheels and tires for the rear. The Torq Thrust D wheel in 15x8" only cost about $200 each and I figured I could sell the old wheels to recoup around half the cost. TireRack shipped the wheels with the tires mounted and balanced in just a few days. But when I removed the packing material I knew I screwed up. The wheels didn't match--I ordered the wrong ones.
American Racing makes many styles of Torq Thrust wheels but only one style comes in both black and a 15" diameter, the Torq Thrust D. I had always assumed that was the style I had since that was the only wheel that came in my size and color. So after more scrutiny of the tiny pictures on AR's website I concluded that I actually had Classic Torq Thrust II's, but mine were painted black instead of the factory argent. Torq Thrust II's start at $400 a piece so I didn't really want to spend $1600 on different sized wheels. If these new wheels fit ok I could always replace the front wheels to match.
I removed the old rear wheels and fitted the new wheels. Before I could tighten down the lug nuts I new these wouldn't work. They stuck out almost as much as the old ones. WTH? I was getting more than a little frustrated at this point. So I took some pictures of the old wheels, reinstalled them on the car and when back to the computer to try and decipher what was what.
Here's a shot of my old wheel. It's a two-piece wheel with a cast aluminum center and a forged rim. That's why they run $400, not including the aluminum center cap. The new wheels are one-piece cast aluminum, thus the cheaper price. Here's a photo from the website.
Close but not quite. The new wheel has a satin finish on the lip while the center cap is plastic! No wonder it's half the price. So why didn't it fit? Besides misidentifying the wheel style, my measurements were off. I measured the wheel width with my calipers by measuring from the outside to the inside of the rim. However, I wasn't accounting for the the thickness of the rim material. Obviously, the tires mount on the inside, not the outside of the rim. So my 8.5" measurement on the outside meant the wheel was only 8" wide. That means I was comparing backspacing for the wrong size wheel. Plus, I was looking at the specs for the wrong style wheel, and they weren't the same. Likewise, my front wheel was only 15x4" not 4.5".
Here's a picture of the backside of the rim. I had to remove black overspray from between the spokes which confirmed that they were repainted. BTW, carb cleaner removed the overspray like magic. You can see that they are indeed 15x08" with what looks like part number 245551. Unfortunately, this number doesn't match anything on American Racing's website. Looking closely at the backside of the wheels they appear to be a lot older than the 1500 miles since the last major rebuild, which was done 10 years ago. So it's possible these wheel are vintage and weren't considered "Classic" when they were made.
At this point I was really wanting to keep to old wheels and decided I would try to fix the rubbing issues by going with smaller tires front and rear. Dropping down from 255/60R15 to 225/60R15 was only going to gain me 15mm of clearance on the outside edge, but the shorter tire would also gain me clearance at the front of the wheel well, where the bigger tire was rubbing. On the front I calculated a 175/65R15 might gain me the necessary clearance, but there are very few tires available in that size. I really wanted the same brand front and rear, mainly for aesthetics. Luckily, BFGoodrich makes the size I wanted for the rear, and a matching skinny tire for the front, 155/80R15. This skinny size is one of the few sizes that fit on narrow drag wheels, which is what I have. At this point, without replacing the front wheels at a cost of $800, I just needed a tire that fit the front wheel and wouldn't rub.
I found this nice calculator at https://www.wheel-size.com/calc/ that gives a nice visual diagram of my fitment issues.
You can see how the existing front tire is way too big for the width of the rim. The new tire fits much better and is even the same height.
The rear diagram doesn't eliminate the interference but it does gain me more suspension travel. So I ordered the new set of tires from Tire Rack and had them shipped directly to the tire shop down the street. They arrived there the next day and I had them installed the following day.
Wow, those front tires are skinny! The best part is they shouldn't ever rub, plus it's a whole lot easy to steer at slow-to-no speeds. It's hard to tell if the rears could still rub, but I definitely gained more suspension travel.
