One of the most important improvement we do to our classic Fords is upgrade the wheels and tires. Not only do wheel and tire sizes usually increase, but we can also take advantage of technology that is ever evolving.
Replacing a steel wheel with one made of aluminum reduces unsprung weight, and that's always a good thing. Another plus is that an aluminum wheel can be a thing of beauty, while a stamped-steel rim is rarely so.
When it comes to tires, few would argue that a bias-ply or bias-belted tire is better than a modern radial. The only exception we can think of is for concours-show usage. Modern radial tire technology just keeps getting better and better, and this is something many classic Ford enthusiasts should take advantage of.
The first issue in any wheel and tire upgrade is determining whether the desired combination will fit your car. You'll want to fill the wheelhouse completely while having no part of the tire protruding from the car and no interference during steering or suspension travel. Remember also that once you mount a tire to a wheel, you've bought both. At that point, no company will refund your money if the combination you've selected doesn't fit your car.
We'll examine some popular wheel and tire upgrades, and talk about some of the different aspects of size that you need to be aware of before you shop for a new set of rolling stock. To begin, you'll need to determine the fitment parameters of your car. First, you must measure the backspacing on the wheel you want and the wheelhouse depth on the car you have.
 The easiest way to measure...  The easiest way to measure backspace is to put the wheel face down on the ground. Lay a straight edge across the rim of the wheel. Using a ruler or tape measure, determine the distance from the straight edge to the face of the flange mounting pad. This measurement is the wheel backspace. On this American Racing rim, the backspacing is 331/44 inches. The offset is the distance from the face of the mounting flange to the true centerline of the wheel. |  The wheelhouse depth must...  The wheelhouse depth must be carefully measured in order to determine what width wheel can be accommodated. Be sure to allow at least 11/42 inch on either side of the wheel for tire sidewall protrusion in your calculations. Take the measurement from the inner wheelhouse to the inside edge of the fender lip. |  Early in the decision process,...  Early in the decision process, look at the potential for brake-caliper interference if your car has disc brakes. Templates are available from brake manufacturers to help determine if your brakes will work with the wheels you want. They may also have a list of workable combinations, although it's difficult to keep track of every possible combination. Even with the templates and a manufacturer's list of applications, the best way to be certain a wheel will clear the brake calipers is to test the fit before you buy the wheels or mount any tires. If necessary, purchase one wheel for the test. Most wheel shops will refund your money if the wheel is returned undamaged and has never had a tire mounted. We test fitted this wheel at all four corners before any tires were mounted. |
 With the wheel seated on the...  With the wheel seated on the axle flange, check for adequate clearance on the inside edge of the rim. Remember that the car's body will tend to roll into the top of the tire's inner sidewall during turns. |  Another clearance checkpoint...  Another clearance checkpoint is this rear-suspension snubber mounting. The outer edge may need to be folded inward or cut off entirely. | |