1964 AC Tire Fitment Guide

1964 AC vehicles use three tire sizes across the model range: 550-16 for the AC Ace, and 640-15 or 670-15 for the AC Cobra and AC Grayhound. The Ace size mounts on a 16-inch rim, while both Cobra and Grayhound sizes mount on 15-inch rims. Rim width guidance is available for all three sizes, with 550-16 covering 3.25 to 4.00 inches, 640-15 covering 4.00 to 5.00 inches depending on the tire, and 670-15 covering 4.50 to 6.00 inches depending on the tire.

That means year and make alone are not enough for a confident selection on 1964 AC vehicles. Start by identifying the model, then confirm the wheel diameter and compare your wheel width to the range used by the tire you want. Once those basics are settled, you can choose the sidewall style and brand that best matches your restoration goals.

On a 1964 AC tire, 550-16 is a numeric bias-ply size. The 5.50 figure is the nominal section width in inches, written without a decimal in modern shorthand, and the 16 is the wheel diameter in inches. It is not a radial code and it does not carry an aspect ratio number in the way a modern metric tire would.

For a 1964 AC Ace owner, that code points you toward the model's correct 16-inch fitment family rather than the 15-inch tires used on the Cobra and Grayhound. It also helps set expectations for appearance and construction: a narrow, tall-sidewall bias-ply tire with a distinctly period profile. Confirm your wheel width before settling on a specific brand or sidewall treatment.

No. The 1964 AC Ace uses 550-16, while the 1964 AC Cobra and 1964 AC Grayhound use 640-15 or 670-15. The Cobra and Grayhound share the same 15-inch fitment family, but the Ace follows a separate 16-inch path, so there is no single tire size that covers every 1964 AC model.

That split matters because it changes more than appearance; it changes the wheel diameter your tire must fit. If you are working from registration paperwork or a project car with mixed parts, verify the model first and inspect the actual wheel before choosing a size. That simple check prevents the most common year-make-level mistake on 1964 AC vehicles.

For a 1964 AC Cobra or 1964 AC Grayhound, both 640-15 and 670-15 are traditional bias-ply sizes that fit 15-inch wheels. The difference is width and overall visual presence rather than a change from bias-ply to radial construction. A 640-15 gives you the narrower of the two shared fitments, while a 670-15 gives you the wider, fuller-looking period size.

The right choice usually comes down to the wheel you have, the stance you want, and how closely you are trying to follow the car's historical presentation. If the car is being judged or restored to a specific market or build style, consult marque references before making the final call. For a driver-level restoration, confirm wheel width and pick the size whose proportions best suit the car.

1964 AC tires are available in several sidewall styles depending on size. The 550-16 used on the Ace comes in blackwall and wide whitewall. The 640-15 used on Cobra and Grayhound comes in narrow whitewall and wide whitewall, while the 670-15 comes in blackwall and wide whitewall.

Sidewall style affects the car's visual character as much as the size itself. Blackwalls usually suit a more sporting or competition-influenced presentation, while whitewalls can lean toward a more formal grand-touring or U.S.-market show look. If authenticity matters, compare your choice to period photos and club guidance for the exact model and market presentation you are aiming to recreate.

Several brands cover 1964 AC vehicles. The 550-16 is available from Excelsior, Avon, BFGoodrich, and Firestone. The 640-15 is available from BFGoodrich and Firestone, and the 670-15 is available from Firestone, US Royal, Coker Classic, and Universal Vintage Tire.

That spread gives an AC owner room to prioritize brand heritage, sidewall appearance, or the exact rim-width range that best matches the wheels on the car. Avon can be especially appealing on a British sports car, while Firestone, BFGoodrich, and US Royal all bring strong period-American visual associations that can make sense on a Cobra. Compare the individual tire details, not just the brand name, before deciding.

Rim width depends on the tire size and, in some cases, the specific tire within that size. On 1964 AC vehicles, 550-16 fits rims from 3.25 to 4.00 inches. The 640-15 fits rims from 4.00 to 5.00 inches depending on the tire chosen, and the 670-15 fits rims from 4.50 to 6.00 inches depending on the tire chosen.

That range is why wheel measurement matters before you settle on a particular product. Two tires with the same size code can overlap but not match exactly in approved rim width. Measure the actual wheel, compare it with the range for the tire you want, and avoid assuming that any tire with the same size stamp will suit every wheel equally well.

1964 AC bias-ply tires can require different setup approaches depending on the exact tire and wheel, so tube use should be confirmed product by product and wheel by wheel. The size markings here do not establish one universal tube rule across every 1964 AC tire. Wheel design, bead condition, and whether the rim was originally intended for tube-type service all matter.

That is especially important on an older British car, where original wheels, restored wheels, or replacement wheels may not all be the same. Before final assembly, inspect the wheel carefully, confirm the tire's sidewall marking, and replace valve stems or tube hardware as part of the installation rather than reusing old components on a collector car.

A 1964 AC Cobra or 1964 AC Grayhound can use both 640-15 and 670-15 on 15-inch wheels because both sizes share the same rim diameter. That means the wheel diameter itself does not force the choice between them. The deciding factor is whether the wheel width falls within the approved range of the specific tire you want to run.

In practice, that makes wheel measurement the key setup step when moving between the narrower and wider 15-inch options. A car with original wheels may accept both sizes, but the fit should still be checked against the chosen tire's rim-width range, sidewall profile, and the clearance available inside the fender and suspension area.

A 1964 AC should be stored in a cool, dry space away from direct sunlight, electric motors, welders, battery chargers, and other ozone-producing equipment that can age rubber prematurely. Keep the tires clean, maintain proper inflation, and move the car periodically if it will sit for long stretches. Bias-ply tires are more prone to temporary flat-spotting during storage than modern radials, so extended static loading deserves extra attention.

For seasonal or long-term storage, many owners either roll the car occasionally or support it in a way that reduces prolonged stress on one contact patch. Avoid parking on bare dirt or damp concrete if possible, and check the spare as carefully as the road tires. A collector car can spend more time aging in storage than it does wearing its tread on the road.

On a 1964 AC, tire age usually matters more than mileage. Collector cars often cover limited annual miles, so the practical service-life question centers on rubber age, storage conditions, and inspection results rather than tread wear alone. A good rule is to evaluate tires closely once they reach about five to seven years of age and to treat roughly ten years as a serious replacement point regardless of remaining tread.

Check the date information on the tire and inspect for cracking, hardening, bulges, or recurring air loss as the tire ages. A lightly used Ace, Cobra, or Grayhound can still be riding on tires that look usable at a glance but have aged out structurally. When in doubt, err on the side of fresh rubber for a car that will be driven at road speeds.

Tires on a 1964 AC should be inspected before every drive and especially before any longer outing. Look for sidewall cracking, cuts, bulges, irregular tread wear, embedded debris, and signs that pressure is not being held consistently. Because these are bias-ply applications on older vehicles, a quick walkaround is not enough if the car has been sitting for weeks or months.

Add a more thorough inspection at regular service intervals, including checking valve stems, wheel condition, and the spare. If your setup uses tubes, pay extra attention to slow leaks and stem condition after storage. That habit matters on an AC because many of these cars see occasional use, and long idle periods can hide tire problems until the day you finally head out for a drive.

A 1964 AC Cobra would have been a bias-ply car in period, and the shared 15-inch Cobra fitments here are 640-15 and 670-15. That aligns with the construction expected for mid-sixties performance and grand-touring applications before radial tires became common in later years. The exact size and sidewall treatment could vary with market, presentation, and restoration goals, so one universal original-equipment answer is too broad for every Cobra.

For a historically faithful restoration, focus first on selecting the correct size family and a period-appropriate sidewall style rather than chasing a brand name unless you have factory or ownership records to support it. Marque clubs, period photography, and surviving unrestored cars are the best tie-breakers when you are refining a car for show-level authenticity.

Correct tire fitment absolutely matters when showing a 1964 AC. Judges and knowledgeable enthusiasts notice whether the car carries the right size family for the model, the correct bias-ply construction for the era, and a sidewall style that matches the way the car would have appeared in period. A mismatch in wheel diameter, an obviously incorrect width, or an overly modern visual treatment can stand out immediately.

That does not mean every event applies the same standard, but originality classes usually reward close attention to these details. An Ace with an appropriate narrow 16-inch bias-ply presentation and a Cobra or Grayhound on the right 15-inch bias-ply family will read more convincingly than a car wearing a size chosen only for convenience. Check the event's judging rules and compare your choice with marque-specific references before finalizing the tire setup.

In 640-15 for the 1964 AC Cobra and 1964 AC Grayhound, BFGoodrich offers a wide whitewall tire rated at 1190 pounds at 32 psi with a 4.00 to 4.50 inch rim-width range. Firestone offers wide whitewall versions also rated at 1190 pounds at 32 psi with a 4.50 to 5.00 inch rim-width range, plus a narrow whitewall version rated at 970 pounds at 32 psi on the same 4.50 to 5.00 inch rim range.

That makes the choice partly visual and partly dimensional. If your wheel is narrower, the BFGoodrich range may align more closely; if your wheel is wider, the Firestone range may be the better match. The narrow-whitewall Firestone also creates a distinctly different sixties appearance from the fuller whitewall styles, so wheel measurement and restoration intent should be weighed together.

1964 AC tires in these fitments are traditional bias-ply designs, and they can be suitable for normal road use when they are fresh, correctly fitted, properly inflated, and in sound condition. One 550-16 Avon option carries an 80L service description, which corresponds to a 75 mph speed capability, while the other sizes here do not show separate speed-letter variation. On a car of this era, tire condition and setup are usually more important than chasing modern high-speed expectations.

The bigger picture is that an Ace, Cobra, or Grayhound is still a sixties machine with era-specific suspension, brakes, steering feel, and chassis behavior. Even when the tires are capable of highway use, the whole car should be treated with the respect due an older performance or touring vehicle. Smooth inputs, proper pressures, and a thorough pre-drive check matter at least as much as the size stamped on the sidewall.

Inflation pressure on 1964 AC tires should follow the vehicle's factory recommendation for the car and the tire maker's pressure limits for the exact tire chosen. Several of these sizes carry load-and-pressure references: 550-16 appears at 840 pounds at 32 psi on one Firestone and 992 pounds on one Avon 80L tire, 640-15 appears at 1190 pounds at 32 psi on several options and 970 pounds at 32 psi on one narrow-whitewall Firestone, and 670-15 ranges from 1450 pounds at 32 psi to 1550 pounds at 32 psi depending on the tire.

Those numbers are not blanket inflation instructions to copy from one size to another. Use them as tire-specific capacity references, then confirm the pressure that suits your exact 1964 AC model, tire size, and vehicle loading. If the car still has its handbook or factory placard information, compare that guidance with the tire's own limits before setting pressures.

Before taking a 1964 AC on a longer drive, inspect all four tires and the spare for cracking, cuts, bulges, uneven wear, and proper inflation. Make sure the wheels are sound, the valve stems are in good condition, and any tire that has sat for a long period does not show severe flat-spotting or age-related stiffness. On a bias-ply car, a careful look at sidewalls and shoulders is especially important.

Treat the tires as one part of a broader road-readiness check that also includes brakes, steering, cooling, and fluid condition. A Cobra may tempt a spirited pace and a Grayhound may encourage longer touring miles, but both deserve the same methodical preparation. If anything about the tire condition feels questionable, resolve it before the trip rather than asking an older collector car tire to prove itself on the road.