1978 American Motors Tire Fitment Guide

1978 American Motors vehicles use ten sizes across five models: B78-14, C78-14, D78-14, DR78-14, E78-14, ER78-14, F78-14, FR78-14, H78-14, and HR78-14. Gremlin uses B78-14 and C78-14, Concord uses C78-14, D78-14, and DR78-14, AMX uses DR78-14, Pacer uses D78-14, DR78-14, E78-14, and ER78-14, and Matador uses F78-14, FR78-14, H78-14, and HR78-14. Every one of those sizes mounts on a 14-inch wheel.

That common 14-inch diameter makes the year look simpler than it really is, because the actual size and construction still change by model. The safest starting point is to identify the exact AMC model first, then compare the tire already on the car or the original fitment references for that model before choosing between bias-ply and radial options.

C78-14 is an alphanumeric bias-ply tire size used on certain 1978 American Motors applications. The letter-number prefix is the older sizing system that indicates the tire’s general width and profile family, and the lack of an R means it is a bias-ply construction. The 14 at the end is the wheel diameter in inches, so a C78-14 mounts on a 14-inch rim.

For a buyer, the important point is that C78-14 belongs to the earlier American sizing language used before modern metric designations became common. On 1978 American Motors cars, it applies to Concord and Gremlin applications, so it should be matched to those models rather than treated as a generic 14-inch tire that automatically fits every AMC of the year.

No. 1978 American Motors models share a 14-inch wheel diameter, but they do not all use the same tire size. The Gremlin uses smaller bias-ply sizes, the Concord mixes bias-ply and radial fitments, the AMX centers on DR78-14, the Pacer spans both D- and E-series sizes in bias-ply and radial form, and the Matador uses larger F- and H-series sizes in both constructions.

That means year and make alone are not enough to choose correctly. A 1978 AMC buyer needs to know whether the car is a Gremlin, Concord, Pacer, Matador, or AMX before narrowing the choice any further, because moving from one AMC model to another can change both the section size family and the construction type.

The right answer depends on which 1978 American Motors model you have and whether that model used a bias-ply size, a radial size, or both across its applications. Concord, Pacer, and Matador all appear with both bias-ply and radial families, while the AMX is tied here to DR78-14 and the Gremlin stays with bias-ply sizing. Bias-ply tires preserve a more period-authentic construction, while radial sizing follows the later construction style AMC was using during the era.

If your goal is restoration accuracy, matching the original construction type for your exact model and application matters more than simply choosing any 14-inch tire. If the car is meant for regular road use, many owners still prefer to stay within the same size family the car used originally, then confirm the wheel and tire markings before making a final choice.

The sidewall styles available for 1978 American Motors sizes here are wide whitewall and blackwall. F78-14 and H78-14 are offered as wide whitewalls through Coker Classic, while E78-14 appears in both a wide whitewall passenger-style version and blackwall STA versions with a more utility-oriented look. Those style differences matter because they change the visual character of the car even when the wheel diameter stays the same.

For a late-1970s AMC, wide whitewalls usually suit buyers restoring a more original passenger-car appearance, especially on larger or more upscale models. Blackwalls can make better sense for a plainer or more utilitarian presentation, particularly when the tire itself leans toward heavier-duty service. Matching the sidewall style to the car’s trim level and intended presentation usually matters as much as the raw size code.

Coker Classic and STA both cover parts of the 1978 American Motors range here. F78-14 and H78-14 are available from Coker Classic, while E78-14 is available from Coker Classic and STA. Within that E78-14 size, Coker Classic focuses on a wide whitewall passenger presentation, while STA offers blackwall versions in the Traxion and Transport Highway families.

That mix gives AMC owners a choice between a more restoration-minded visual style and a more work-oriented blackwall look, depending on the exact size and application. Brand choice should come after you confirm the correct tire code for your model, because the available brands are tied closely to the size rather than spread evenly across the whole 1978 AMC lineup.

The rim width requirement depends on the exact 1978 American Motors tire size. F78-14 fits rims from 5.00 to 7.00 inches wide, H78-14 fits rims from 5.50 to 8.00 inches wide, and E78-14 appears with at least two published ranges: 4.50 to 7.00 inches on one passenger-style tire and 5.0 to 6.0 inches on one STA Traxion version. All of those sizes use a 14-inch rim diameter.

That overlap is useful, but it also shows why wheel width matters before ordering. Two tires with the same basic size code may not share the same approved width range, especially when one is a traditional passenger tire and another is built for a more commercial-style application. Checking the actual wheel width on the car avoids mounting a tire on a rim that falls outside its intended range.

Original 1978 American Motors wheels can often accept more than one tire size in this year’s range because every size here is built for a 14-inch rim diameter. That means the basic wheel diameter matches across the Gremlin, Concord, Pacer, Matador, and AMX applications. Diameter compatibility alone does not make every tire interchangeable, though, because section size and approved rim-width range still change from one code to another.

A practical approach is to treat the 14-inch wheel diameter as only the first checkpoint. After that, compare your exact wheel width to the approved range for the tire you want to use and stay within the size family intended for your AMC model. That preserves proper proportions and avoids forcing a wider or narrower tire onto a wheel it was not designed to use.

A stored 1978 American Motors should be kept out of direct sunlight and away from ozone sources such as electric motors, battery chargers, furnaces, and welding equipment. Clean, dry concrete is better than damp ground, and the car should either be moved periodically or supported in a way that reduces long static loading. Bias-ply tires are especially prone to temporary flat-spotting during long storage compared with radials.

Storage habits have a direct effect on how the car feels when it returns to the road. A collector AMC that sits for long periods benefits from stable inflation pressure, occasional rotation of the tires under load, and a quick inspection before driving again. That routine is especially worthwhile on late-1970s cars that may alternate between long storage periods and occasional weekend use.

Tire life on a 1978 American Motors is usually limited more by age than by mileage. Collector-car tires often deserve close evaluation once they reach about five to seven years of age, and replacement becomes a serious consideration as they approach the ten-year mark, even if the tread still looks healthy. The DOT date code on the sidewall is the best starting point for determining age.

That age-based approach matters because many AMC cars are driven infrequently and can appear fine while the rubber is already hardening. A low-mileage tire is not automatically a fresh or trustworthy one. If the date code shows real age, or if the sidewalls are checking and the ride has become harsh, replacement is usually wiser than trying to stretch service life further.

Tires on a 1978 American Motors should be inspected before every drive, with a more thorough check before any longer outing. Look for sidewall cracking, cuts, bulges, uneven tread wear, and pressure loss, and pay attention to how the car feels in the first few miles. On bias-ply applications, changes in tracking or ride quality can be an early clue that the tire needs closer inspection.

Frequent inspection is particularly important on collector cars because long idle periods can hide gradual deterioration. If the car carries a tube-type application, valve stems and the condition of the inner tube system deserve attention as well during service. A few minutes of inspection before a trip can prevent a roadside problem and often reveals age-related issues before they become obvious failures.

The 1978 American Motors Concord appears with C78-14, D78-14, and DR78-14 fitments, which shows that both bias-ply and radial construction were part of the model’s tire story during this period. By the late 1970s, American manufacturers were in the middle of the shift toward radials, so either construction can be historically relevant depending on the exact application. The key is matching the size and construction to your car rather than assuming one answer covers every Concord.

For restoration work, sidewall style and overall visual character should be considered alongside the size code itself. If originality is important, compare your car’s surviving labels, manuals, and old photos with marque-club guidance before making the final call. That extra step is worthwhile because late-1970s cars often sit right at the crossover point where tire construction could vary within the same model family.

Correct tire fitment absolutely matters when a 1978 American Motors is judged for authenticity. Size, construction type, sidewall style, and overall stance all affect whether the car looks right for its era and trim level. On a late-1970s AMC, a blackwall utility-style tire, a wide whitewall passenger tire, and a radial replacement can create very different impressions even when the wheel diameter is still 14 inches.

Judges and knowledgeable AMC enthusiasts typically notice mismatches in construction or sidewall presentation before they ever look at minor details. If your car is headed for a serious show, confirm what the event expects, because some venues reward period-correct appearance while others place stronger weight on exact factory-style specifications. Marque clubs and factory literature are the best tie-breakers when the car falls into a radial-transition year.

Within the 1978 American Motors E78-14 size, the Coker Classic and STA options serve noticeably different purposes. The Coker Classic E78-14 is a bias-ply wide whitewall rated at 1,400 pounds at 32 psi with a 4.50 to 7.00 inch rim-width range, while the STA Traxion E78-14 is a blackwall bias-ply tire with an 8-ply rating and a single-load figure of 1,710 pounds at 60 psi on a 5.0 to 6.0 inch rim range. STA also offers a blackwall Transport Highway version in the same size family.

That means the choice is not just brand preference. The Coker Classic better suits a passenger-car restoration look, while the STA tires lean toward a heavier-duty visual and service character. Before choosing between them, compare the wheel width on the car and decide whether the goal is an authentic whitewall presentation or a more utilitarian blackwall bias-ply setup.

A correctly sized, properly maintained tire for a 1978 American Motors can be appropriate for normal highway use, but safety depends on matching the tire to the model, wheel, and condition of the car. The tires shown here are a mix of bias-ply and radial fitments, and highway confidence on a late-1970s AMC is affected not only by the tire itself but also by alignment, suspension wear, brake condition, and age of the rubber. A sound tire cannot compensate for a neglected car.

The practical takeaway is to evaluate the whole package before a trip. A freshly restored or well-maintained AMC on the correct size and properly inflated tires can be very usable, while an older car with cracked sidewalls, unknown tire age, or worn steering parts should be sorted first. Highway use should be approached with the car’s era, condition, and intended construction type all in mind.

Inflation pressure for 1978 American Motors tires should follow the factory recommendation for the car and the tire maker’s stated limits for the exact product. Among the sizes with published figures here, F78-14 carries 1,500 pounds at 32 psi, H78-14 carries 1,770 pounds at 32 psi, the Coker Classic E78-14 carries 1,400 pounds at 32 psi, and the STA Traxion E78-14 reaches 1,710 pounds single load at 60 psi. Those figures are load-capacity references, not a blanket pressure setting for every AMC application.

The safest approach is to start with the vehicle manufacturer’s recommendation for your model, then make sure the tire you choose supports that use on the correct wheel. Do not transfer pressure numbers from an STA commercial-style E78-14 to a passenger whitewall tire, or from a Matador size to a Pacer size, simply because they share a 14-inch rim diameter.

Before a longer drive in a 1978 American Motors, inspect each tire for cracks, cuts, bulges, exposed cord, unusual wear, and proper inflation. Make sure the spare is usable, confirm that valve stems are sound, and look closely at any tire that has been sitting under load for a long period. A quick rolling check in the first few miles can also reveal vibration or flat-spotting that was not obvious in the garage.

Tires are only one part of the pre-drive checklist on a car from this era, but they are one of the easiest places to catch trouble early. After the tire inspection, continue with the basics: wheel hardware, brakes, fluids, steering feel, and lights. That broader check is especially important on AMC cars that may spend weeks or months between outings and then suddenly be asked to handle a full-day trip.