Mark Houlahan
Tech Editor, Mustang Monthly
June 1, 2001
Contributers: Jeff Ford Photos By: Jeff Ford

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As an experiment, we set up our ’73 Project vehicle with the BFGoodrich radial equivalent of the F70-14 that originally came on the car. These tires are tall and offer a good, soft ride but will not hold in the corners as well as a low-profile tire.
This is a good example of plus-sizing a tire. The BFG on top is a P235/60R15 and the BFG on the bottom is a P205/70R14. Note, the rolling diameters are identical.
The Mach 1 is now dressed out in what is arguably the most popular Ford rim available: the Magnum 500. These particular Mags are from Specialty Wheels and are mounted with the P235/60R15 tire. This tire is a close replacement for the size that Ford originally used on this rim, the F60-15. Also note, plus-sizing has reduced the tire sidewall but kept the approximate 26-inch diameter. This tire also gives better handling due to its lower sidewall profile. Unfortunately, ride—when compared to the 70-series tire—will suffer.
Up next is the really big meat. On top is the P235/60R15, and on the bottom is the P255/50R16. Both carry an approximate 26-inch diameter. Only the ’71-’73 cars need apply for this particular width of tire; other year models might support the tire in the rear, but the tire could cause some serious conflicts up front.
This is what happens with Specialty Wheels’ new 16-inch Magnum. Stealthy! Many folks will assume you have a set of 15-inch 500s on your car, but you’ll know the truth. The only giveaway is the lack of lettering on the BFGs. Most performance tires from BFG don’t carry raised-white-letters beyond the 15-inch width. As with the 235 series, the sidewall is again smaller and handling will improve once again, but ride will suffer.
These 16x7-inch Halibrands and P225/55R16 BFGs are set for installation on a sister publication’s Project ’66 Ranchero. We stole the wheels to see what an aftermarket set would do for the ’73. Hmmm. Wheels; we didn’t see any wheels for a Ranchero. These wheels with their near-factory offset would work very nicely on any Ford product—even on a ’65-’66 Mustang.
The four tires tested are shown left to right: P205/70R14, P225/55R16, P235/60R15, and P255/55R16.

It can make you dizzy—this thing called tire-and-wheel selection; especially when you get involved with plus-sizing and try to figure out what type of tire or wheel you need. Reams of paper have been written on this subject, and a good amount of bandwidth on the Internet has been devoted to it. What we’re going to do for you here is remove some of the mystery and make it easier for you to make the “right choice” on the tire front. Where wheels are concerned, we will not profess to know what the ultimate wheel package is for your vintage Mustang. But we will show you how plus-sizing affects the look and feel of a ’73 Mach 1. First, we’ll throw on the stock ’73 slotted wheel, followed by Specialty Wheels’ excellent reproduction Magnum 500 in both 15- and—the new—16-inch sizes. Finally, we’ll throw on a set of 16-inch Halibrand five-spokes to see what this beautiful custom wheel can do for your Mustang.

Also, select from the sidebars below for sizing information and helpful formulas.