The 1978 American Motors Concord arrived as AMC’s more refined compact, blending practical everyday use with the squared-off styling and ride character that defined late-1970s American cars. For owners today, that makes tire choice part fitment question and part character decision, especially on a car that may be preserved, restored, or regularly driven. The 1978 American Motors Concord uses 14-inch fitments in C78-14, D78-14, and DR78-14, with both bias-ply and radial applications depending on sub-model. That opens the door to traditional bias-ply sizing as well as modern radial-equivalent consideration in some cases. The key is matching the exact sub-model first, then choosing the tire construction and appearance that best suit the car’s intended use.
Which Tire Size Is Right for The 1978 American Motors Concord
The 1978 American Motors Concord uses three primary tire sizes, all built around a 14-inch rim, and the correct choice depends on the exact sub-model. Some versions use bias-ply sizes C78-14 or D78-14, while certain 8-cylinder applications also use DR78-14 radial construction. Before choosing a tire, confirm which Concord configuration you have so the size and construction match the car’s wheel setup and intended use.
C78-14 is a vintage alphanumeric bias-ply size in which the letter identifies the tire’s size class, the 78 marks its profile family, and the 14 identifies rim diameter. On the 1978 American Motors Concord, it represents a traditional bias-ply fitment for certain sub-models and suits owners who want to stay close to the car’s period tire construction. Its modern radial equivalents move into metric sizing rather than repeating the original alphanumeric code. C78-14 is worth considering when the goal is a restoration-oriented presentation and the car still uses the wheel and suspension setup intended for that size.
D78-14 uses the same vintage alphanumeric bias-ply system, with the letter designating the tire’s size class, the series number indicating its profile family, and the final number showing the 14-inch rim diameter. For the 1978 American Motors Concord, this size sits within the same traditional fitment approach but applies to different covered configurations than C78-14. Because it is a primary bias-ply size, the decision is less about decoding the format and more about confirming that this is the correct Concord application before comparing tire style and construction alternatives. It is best evaluated alongside the car’s exact sub-model and wheel setup.
DR78-14 follows the alphanumeric radial system, where the letter defines the size class, the R indicates radial construction within the designation, the 78 refers to the profile family, and the 14 is the rim diameter. On the 1978 American Motors Concord, this size matters because it reflects a primary radial fitment for certain 8-cylinder versions rather than a later conversion. That makes it especially useful for owners who want a period-appropriate radial-size presentation without stepping into a different modern metric format. It should still be matched carefully to the correct sub-model and existing wheel dimensions.
Sub-model fitment matters on the 1978 American Motors Concord because tire size and construction are not the same across every version. Some covered sub-models share bias-ply sizing, while certain 8-cylinder applications also introduce a primary radial option, so identifying the exact Concord configuration comes first.
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1978 American Motors Concord 6 Cyl.
The 1978 American Motors Concord 6 Cyl. uses bias-ply sizing, with C78-14 or D78-14 applying to covered configurations. That makes the main decision one of confirming the exact fitment, then choosing the tire style and presentation that best suit a restoration-oriented car or a regularly driven period compact.
The 1978 American Motors Concord 8 Cyl. introduces a split fitment path, using either D78-14 bias-ply or DR78-14 radial sizing depending on configuration. That means construction choice is part of the original fitment story here, so the wheel setup and the exact application should be verified before selecting a replacement tire.
The 1978 American Motors Concord Hatchback 6 Cyl. follows the same bias-ply fitment pattern seen on covered 6-cylinder applications, using C78-14 or D78-14. Tire selection should focus on confirming which of those two sizes belongs on the car, then choosing a period-style option that matches its appearance and road-use plans.
The 1978 American Motors Concord Wagon 8 Cyl. uses either D78-14 bias-ply or DR78-14 radial sizing in the covered fitments. That makes it important to confirm whether the wagon is set up for the bias-ply or radial application before comparing replacement tires or considering any change in construction.
Bias-Ply to Radial Tire Conversion for the 1978 American Motors Concord
C78-14 has three radial-equivalent options for owners considering a modern alternative. Those equivalents are 175R14 as an 80-series metric radial, P185/75R14 as a 75-series P-metric radial, and P195/70R14 as a 70-series P-metric radial. Each one represents a different modern sizing convention and profile approach relative to the original alphanumeric bias-ply size. A recommended rim-width range of 4 to 6 inches is associated with these alternatives, and wheel width, overall dimensions, and clearance should all be checked before making the change.
Modern Radial Equivalents
175R14
Equivalent 80-series Metric Radial (C78-14)
P185/75R14
Equivalent P-metric 75-series Radial (C78-14)
P195/70R14
Equivalent P-metric 70-series Radial (C78-14)
Important Considerations When Replacing Bias Ply With Radial
Compare overall diameter and section width carefully to ensure proper fit.
Verify recommended rim range (4-6 in) and load needs match your vehicle specifications.
Check fender clearance, steering clearance, and stance before installation.
Consider suspension condition and intended road use when choosing equivalents.
Important Fitment Notes
The tire sizes listed on this page assume factory-standard vehicle configuration. The following modifications may affect tire fitment and are not reflected in this guide:
Suspension changes (lowering, lift kits, spring replacements)
Body alterations (fender modifications, custom bodywork)
If your vehicle has been modified from factory specifications, verify tire clearance before purchase.
Frequently Asked Questions
Common questions for the 1978 American Motors Concord usually center on identifying the right 14-inch tire size by sub-model, understanding bias-ply versus radial applications, and knowing what to inspect before putting a vintage AMC back on the road.
Tire Size & Fitment
What tire size fits a 1978 American Motors Concord?
The 1978 American Motors Concord uses three primary tire sizes: C78-14, D78-14, and DR78-14. All three fitments use a 14-inch rim, but they do not apply across every Concord sub-model in the same way. C78-14 and D78-14 are bias-ply sizes, while DR78-14 is an alphanumeric radial size used on certain 8-cylinder applications.
The practical first step is confirming the exact Concord sub-model before choosing a tire. A 6-cylinder car may follow a different fitment path than an 8-cylinder car, and some covered applications allow more than one primary size. Matching the car’s existing wheel diameter and verifying whether it is set up for bias-ply or radial construction will help narrow the choice correctly.
What size rim does a 1978 American Motors Concord use?
The covered tire sizes for a 1978 American Motors Concord all use a 14-inch rim diameter. That includes C78-14, D78-14, and DR78-14, so the rim diameter remains consistent even though the tire sizes and constructions vary by application. The difference is in the tire code and construction type rather than a change in wheel diameter.
Rim diameter is only one part of fitment, so it should not be treated as the whole answer. A Concord with 14-inch wheels still needs the correct tire size for its sub-model, and wheel width should be checked as well if the car has been changed from its original-style setup. That becomes especially important when comparing bias-ply sizing to radial alternatives.
Do all 1978 American Motors Concord sub-models use the same tire size?
No, the 1978 American Motors Concord does not use one tire size across every covered sub-model. Covered 6-cylinder applications use C78-14 or D78-14 bias-ply sizing, while certain 8-cylinder versions use D78-14 bias-ply or DR78-14 radial sizing. The size and construction both vary within the Concord range for this model year.
That variation means a buyer should identify the exact Concord sub-model before comparing tires. A Hatchback 6 Cyl. and a Wagon 8 Cyl. do not necessarily follow the same fitment path, even though both use 14-inch rims. Checking the actual wheel setup on the car is also wise, especially if the vehicle has been modified or has replacement wheels from an earlier repair or restoration.
Bias-Ply & Radial Options
Is C78-14 a bias-ply or radial tire for the 1978 American Motors Concord?
C78-14 is a bias-ply tire size on the 1978 American Motors Concord. It uses the vintage alphanumeric bias-ply sizing system, with the letter marking the size class, the series number reflecting the profile family, and the 14 identifying the rim diameter. It is one of the primary Concord fitments rather than a modern substitute size.
That matters because a bias-ply tire keeps the car within its original-style sizing format and construction approach for the covered application. Buyers considering a change should compare wheel width, clearance, and the intended use of the car before moving to a radial alternative. A restoration-minded Concord may call for different priorities than one meant for regular weekend road use.
What radial tire sizes are equivalent to C78-14?
Radial equivalents for C78-14 include 175R14, P185/75R14, and P195/70R14. The 175R14 option is an 80-series metric radial, P185/75R14 is a 75-series P-metric radial, and P195/70R14 is a 70-series P-metric radial. These sizes offer modern radial sizing paths while referencing the original C78-14 fitment.
Each equivalent should be treated as an alternative to evaluate, not as an automatic interchange. The recommended rim-width range associated with these equivalents is 4 to 6 inches, and the car’s actual wheel width, physical clearance, and overall setup should be checked before making the switch. That helps avoid choosing a radial size that looks or fits differently than expected.
What should I check before converting my 1978 American Motors Concord from bias-ply to radial tires?
Start by confirming which original bias-ply size belongs on the car and whether a true radial equivalent is available for that specific size. On the 1978 American Motors Concord, radial-equivalent information is present for C78-14, while some covered applications also use DR78-14 as a primary radial fitment. Rim diameter stays at 14 inches, but size and construction vary by sub-model.
A careful conversion also means checking wheel width, overall tire dimensions, and clearance at the fenders and steering components. The car’s suspension condition matters as well, particularly on a low-use collector vehicle that may have worn bushings or sagging springs. If the Concord has aftermarket wheels or any ride-height changes, those details should be verified before committing to a radial alternative.
Choosing the Right Tire
What should I consider when choosing a C78-14 tire for a 1978 American Motors Concord?
The first consideration is making sure C78-14 is actually the primary size for your 1978 American Motors Concord sub-model. C78-14 is a vintage alphanumeric bias-ply fitment, so choosing it means staying with the original-style sizing convention and construction family used on certain covered applications. It should not be selected simply because it shares the same 14-inch rim diameter as the other Concord sizes.
Once the fitment is confirmed, the choice becomes more about how the car will be used and presented. A Concord aimed at restoration-style appearance may benefit from staying in its primary bias-ply format, while a regularly driven car may lead the owner to compare available radial-equivalent paths. Wheel width, vehicle stance, and the overall look you want from the tire should guide the final decision.
How do I choose between the available 14-inch tire sizes for a 1978 American Motors Concord?
Choosing between the 14-inch tire sizes on a 1978 American Motors Concord starts with identifying the sub-model and existing tire construction. C78-14 and D78-14 are bias-ply sizes, while DR78-14 is a radial size used on certain 8-cylinder applications. Even though all three share the same rim diameter, they are not interchangeable primary fitments across the whole Concord range.
A useful way to narrow the decision is to confirm whether the car is a 6-cylinder, 8-cylinder, hatchback, or wagon application and then inspect the wheels already on it. From there, think about whether the goal is a traditional bias-ply presentation or a radial-style setup where applicable. That approach keeps the choice grounded in fitment rather than making it a cosmetic guess.
What rim-width specifications should I compare when choosing 1978 American Motors Concord tires?
Rim width becomes most relevant when comparing radial alternatives to the original bias-ply sizing. For the C78-14 equivalents, the associated recommended rim-width range is 4 to 6 inches. That range helps frame whether a modern radial alternative is being matched to a wheel that supports the intended tire dimensions.
The smartest comparison is between the wheel actually on the car and the tire being considered, especially if the Concord has been restored with replacement wheels or later modifications. A 14-inch diameter match alone is not enough. Checking width before installation can help avoid unwanted changes in sidewall shape, clearance, or overall appearance once the tire is mounted.
Restoration & Appearance
Which tire should I choose for a period-style 1978 American Motors Concord?
A period-style 1978 American Motors Concord usually starts with using the correct primary size and construction for the specific sub-model. That may mean C78-14 or D78-14 in bias-ply form, or DR78-14 on covered 8-cylinder radial applications. Staying within the original-style alphanumeric sizing format keeps the car visually closer to its late-1970s tire presentation.
Construction choice affects both look and character, so the decision should follow the car’s restoration goals. A preservation-oriented Concord may favor its primary bias-ply fitment, while another owner may consider a radial alternative where appropriate for road use. When exact originality matters, period photos, marque references, and vehicle-specific documentation remain the best final check.
How does tire construction affect the appearance of a restored 1978 American Motors Concord?
Tire construction changes more than how the car drives; it also changes how a restored 1978 American Motors Concord presents. Bias-ply tires in sizes such as C78-14 or D78-14 keep the vintage alphanumeric format and the traditional look associated with the car’s era. DR78-14 keeps a period radial-style designation, while modern metric equivalents introduce a newer-looking size language.
That difference matters if the car is being restored with close attention to period character. Even when a radial alternative is practical, the visual impression at the wheel opening can shift once the sidewall and sizing format change. Matching the tire to the restoration’s purpose, rather than choosing only by convenience, usually leads to a more satisfying result.
Fitment, Maintenance & Road Use
Can modifications affect tire fitment on a 1978 American Motors Concord?
Yes, modifications can affect tire fitment on a 1978 American Motors Concord even when the tire size appears correct on paper. Aftermarket wheels, changes in wheel width, suspension lowering, replacement springs, or bodywork can all alter the space available for a C78-14, D78-14, or DR78-14 tire. That is especially important on a car that may have passed through several owners over the years.
The safest approach is to inspect the actual wheel and surrounding clearance before choosing a replacement tire. Turning clearance at full steering lock, vertical clearance at the fender opening, and the condition of suspension components all influence whether the intended fitment still makes sense. A vintage Concord with stock dimensions and a modified one may need very different verification steps.
What should I inspect before driving a 1978 American Motors Concord on new tires?
Before driving a 1978 American Motors Concord on new tires, inspect the wheels for correct diameter and condition, confirm the tire size matches the sub-model, and check that the tires are mounted and inflated properly. It is also wise to look over the valve stems, wheel hardware, and the suspension and steering parts that support the car’s stance and tracking.
A short, careful first drive can reveal issues that are easy to miss while the car is stationary. Watch for rubbing, unusual pull, vibration, or signs that the tires are contacting a fender or steering component under load. On a collector car that sits often, those checks matter just as much as the new tires themselves because old chassis parts can affect the result.
How should tires on a collector 1978 American Motors Concord be maintained?
Tires on a collector 1978 American Motors Concord should be inspected regularly for air loss, cracking, bulges, cuts, and uneven tread wear, even if the car is driven only occasionally. Low annual mileage does not prevent aging, and long periods of storage can be hard on both bias-ply and radial tires. Pressure checks remain important before each drive, especially after the car has been sitting.
Storage conditions also play a major role in long-term tire health. Keeping the Concord away from prolonged sunlight, moisture, excess heat, and ozone sources such as electric motors can help preserve the tires between outings. A longer trip deserves an extra inspection of tread, sidewalls, and overall condition so the car is not asked to cover distance on tires that only look sound at a glance.
