The 1979 Mercury Capri arrived at an interesting moment for compact American sporty cars, blending Fox-platform practicality with a more European-flavored shape and a wide range of four-cylinder, six-cylinder, and V8 configurations. That variety carries directly into tire selection, because this Capri can use both 13-inch and 14-inch fitments, with bias-ply and radial applications depending on the sub-model. Sizes include B78-13, C78-13, BR78-14, CR78-14, and C78-14, and some of those sizes also open the door to modern radial equivalents. The right choice comes down to confirming the exact Capri configuration first, then balancing period-style appearance, construction type, and wheel compatibility.
Which Tire Size Is Right for The 1979 Mercury Capri
Five primary tire sizes apply to the 1979 Mercury Capri, and they do not all fit the same configuration. The first step is identifying the exact sub-model, because Capri fitment varies by engine grouping and includes both 13-inch and 14-inch rim diameters as well as bias-ply and radial constructions. Once that is confirmed, the decision shifts to choosing the right size within the proper construction and evaluating whether a period-style bias-ply or a radial alternative better suits the car.
B78-13 is a vintage alphanumeric bias-ply size in which the letter identifies the size class, the 78 designates the profile family, and the 13 refers to a 13-inch rim. On the 1979 Mercury Capri, this is a traditional bias-ply fitment used on certain four-cylinder applications. Buyers familiar only with modern metric sizing may also want to note that this size has radial-equivalent alternatives in other formats. It is the kind of fitment to evaluate carefully when maintaining a period-style look on a Capri that still uses its proper 13-inch wheel setup.
C78-13 follows the same vintage alphanumeric bias-ply sizing system, with the letter denoting a larger size class than B78, the 78 marking the profile family, and the 13 indicating rim diameter. For a 1979 Mercury Capri, this is another 13-inch bias-ply fitment associated with specific four-cylinder versions rather than the full model range. Its practical role is to preserve the original-era sizing format on cars equipped for 13-inch tires. Before choosing it, confirm which of the two 13-inch bias-ply sizes belongs on the exact Capri configuration and wheel package.
BR78-14 is an alphanumeric radial size, with the R built into the designation to indicate radial construction and the 14 identifying a 14-inch rim. On the 1979 Mercury Capri, this size appears on several six-cylinder and Ghia or RS applications, making it a key fitment for buyers looking at later-style radial behavior within the original-era sizing system. Because it is already a radial primary fitment, the decision here is less about conversion and more about confirming the exact sub-model and wheel diameter. That makes it especially important on cars that may have changed wheels over time.
CR78-14 is another alphanumeric radial size, with a larger size class than BR78-14 and a 14-inch rim requirement. It is one of the most broadly used 14-inch fitments on the 1979 Mercury Capri, appearing across several six-cylinder, Ghia, RS, and V8 applications. Its importance lies in that wide sub-model coverage while still not being universal across every Capri built that year. Anyone selecting CR78-14 should verify the car's specific trim, engine grouping, and actual wheel setup so the radial size matches both the intended appearance and the hardware on the car.
C78-14 is a vintage alphanumeric bias-ply tire size that uses the familiar letter-plus-series format and mounts on a 14-inch rim. For the 1979 Mercury Capri, this size appears in a V8 application and stands apart because it shares the 14-inch wheel diameter used by radial sizes while retaining bias-ply construction. That gives it a different buyer decision than the 13-inch bias-ply options, since construction choice becomes part of the conversation even on the same rim diameter. It is worth close attention on restoration-oriented V8 cars where appearance and driving feel both matter.
Sub-model fitment matters on the 1979 Mercury Capri because tire size changes across the range. Some versions use 13-inch bias-ply tires, while others move to 14-inch radial fitments, so confirming the exact Capri configuration is the first step before comparing brands, sidewall presentation, or radial-equivalent options.
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1979 Mercury Capri 4 Cyl.
The 1979 Mercury Capri 4 Cyl. uses 13-inch bias-ply fitments rather than the 14-inch radial sizes found elsewhere in the lineup. That means tire selection starts with confirming which of the two 13-inch sizes belongs on the car, then deciding whether to stay with a traditional bias-ply presentation or explore a radial equivalent where available.
The 1979 Mercury Capri 6 Cyl. moves to 14-inch radial fitment, using alphanumeric radial sizing rather than the smaller 13-inch bias-ply applications. That makes wheel diameter confirmation especially important, followed by selecting the correct 14-inch radial size for the car's exact setup.
The 1979 Mercury Capri Ghia & RS 4 Cyl. uses 14-inch radial fitment, matching the more modern construction approach seen on several upper Capri configurations. Tire choice here centers on confirming the exact radial size used on the car and then comparing available options in the proper 14-inch format.
The 1979 Mercury Capri Ghia & RS 6 Cyl. also uses 14-inch radial sizing, so the main fitment issue is choosing the correct alphanumeric radial size for the specific car. Buyers should verify the wheel setup first, especially on cars that may have seen replacement wheels over the years.
The 1979 Mercury Capri Ghia & RS Opt. V8 is tied to a single 14-inch radial size, which makes fitment more straightforward than on some other Capri versions. Once the wheel diameter is confirmed, the focus becomes selecting the right radial tire character and appearance for the way the car is being restored or driven.
The 1979 Mercury Capri V8 can involve either a 14-inch bias-ply or a 14-inch radial fitment, so construction choice is part of the selection process as well as size. That makes this one of the most important Capri sub-models to verify carefully before ordering, especially if the goal is to preserve a traditional look or maintain an existing wheel and suspension setup.
Bias-Ply to Radial Tire Conversion for the 1979 Mercury Capri
B78-13 and C78-14 each have radial-equivalent options that give the 1979 Mercury Capri owner more than one path forward. For B78-13, the choices are 175R13 as an 80-series metric radial, P175/75R13 as a 75-series P-metric radial, P185/70R13 as a 70-series P-metric radial, and 650R13 as a bias-look radial. For C78-14, the equivalents are 175R14 in 80-series metric form, P185/75R14 in 75-series P-metric form, and P195/70R14 in 70-series P-metric form. Both mappings use a recommended rim-width range of 4 to 6 inches, and wheel compatibility plus vehicle clearance should still be checked before changing sizes or construction.
Modern Radial Equivalents
175R13
Equivalent 80-series Metric Radial (B78-13)
P175/75R13
Equivalent P-metric 75-series Radial (B78-13)
P185/70R13
Equivalent P-metric 70-series Radial (B78-13)
650R13
Bias-look Radial Equivalent (B78-13)
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 1979 Mercury Capri usually come down to sorting out the correct sub-model fitment, understanding its mix of bias-ply and radial sizes, and deciding how much weight to give to period-style appearance, wheel compatibility, and road-use practicality.
Tire Size & Fitment
What tire size fits a 1979 Mercury Capri?
The 1979 Mercury Capri uses five possible primary tire sizes: B78-13, C78-13, BR78-14, CR78-14, and C78-14. Those sizes are not universal across the model range, because Capri fitment changes by sub-model and includes both bias-ply and radial constructions.
The practical first step is identifying the exact Capri configuration and confirming whether the car is on a 13-inch or 14-inch wheel. Once that is established, tire selection becomes much easier, since the buyer can focus on the right size family, the correct construction type, and any relevant radial-equivalent alternatives without crossing into a different Capri setup.
What size rim does a 1979 Mercury Capri use?
A 1979 Mercury Capri can use either a 13-inch or 14-inch rim, depending on the specific sub-model and tire size. B78-13 and C78-13 are 13-inch fitments, while BR78-14, CR78-14, and C78-14 are designed for 14-inch rims.
That rim difference matters because it separates the smaller four-cylinder bias-ply applications from several of the larger 14-inch radial or V8-related fitments. Checking the actual wheel diameter on the car is important before selecting tires, especially on a Capri that may have had wheels changed during restoration, customization, or routine replacement over the years.
Do all 1979 Mercury Capri sub-models use the same tire size?
No, 1979 Mercury Capri sub-models do not all use the same tire size. Four-cylinder cars can use 13-inch bias-ply sizes, several six-cylinder and Ghia or RS versions use 14-inch radial sizes, and V8 applications can involve either a 14-inch bias-ply or 14-inch radial fitment.
That variation means the sub-model is not just a catalog detail; it is central to getting the fitment right. Buyers should confirm the exact Capri version first, then verify the wheel diameter currently on the car, since the correct tire choice depends on both the original application and any changes made to the wheels over time.
Bias-Ply & Radial Options
Is B78-13 a bias-ply or radial tire for the 1979 Mercury Capri?
B78-13 is a bias-ply tire size on the 1979 Mercury Capri. It uses the vintage alphanumeric sizing system and belongs to the 13-inch fitment group found on certain four-cylinder Capri applications rather than the 14-inch radial group used on several other sub-models.
That matters because a buyer considering B78-13 is usually making a construction decision as much as a size decision. A traditional bias-ply keeps the original-style sizing format, while radial alternatives can be considered separately. Before changing construction, confirm the wheel width, the vehicle's current wheel setup, and the available clearance around the tire.
What radial tire sizes are equivalent to B78-13 and C78-14?
For B78-13, radial equivalents include 175R13, P175/75R13, P185/70R13, and the bias-look radial 650R13. For C78-14, the radial equivalents are 175R14, P185/75R14, and P195/70R14. Both primary sizes are associated with a recommended rim-width range of 4 to 6 inches.
Those options give different sizing formats and profile conventions without changing the fact that they remain alternatives rather than automatic replacements. Metric 80-series, 75-series P-metric, 70-series P-metric, and bias-look radial choices should each be checked against the Capri's wheel, overall stance, and available clearance before making the switch from the original bias-ply fitment.
Should I use bias-ply or radial tires on a 1979 Mercury Capri?
That depends on which 1979 Mercury Capri sub-model is being fitted and what the goal is for the car. Some Capri applications use bias-ply sizes such as B78-13, C78-13, or C78-14, while others already use primary radial sizes such as BR78-14 or CR78-14.
A restoration-oriented owner may prefer to stay with the original-style construction format used by that particular Capri configuration, while a road-use-focused owner may want to evaluate one of the stated radial equivalents where available. The key is to keep the decision tied to the exact sub-model, wheel diameter, and intended appearance rather than treating every Capri as the same.
Choosing the Right Tire
What should I consider when choosing a 1979 Mercury Capri tire?
Start with the exact sub-model, because the 1979 Mercury Capri spans five primary sizes, two rim diameters, and both bias-ply and radial constructions. The correct choice depends first on whether the car uses a 13-inch or 14-inch wheel and whether its original application falls into a bias-ply or radial fitment group.
After the basic fitment is confirmed, focus on the kind of Capri being built or driven. Some owners want a period-style presentation that stays close to the original construction type, while others may be comparing a bias-ply size with a stated radial equivalent. Wheel setup, intended use, and the visual character of the tire should all guide the final decision.
How do I choose between the available 14-inch tires for a 1979 Mercury Capri?
Choosing among 14-inch 1979 Mercury Capri tires starts with determining whether the car needs BR78-14, CR78-14, or C78-14. That matters because the first two are radial alphanumeric sizes, while C78-14 is a bias-ply size used in a V8 application.
Once the proper size is narrowed down, construction becomes the next major factor. A radial primary fitment keeps the car in its intended 14-inch radial size family, while a V8 Capri using C78-14 raises a more deliberate choice between preserving a traditional bias-ply setup or considering one of the stated radial-equivalent paths where applicable.
How do I choose between the available B78-13 tires for a 1979 Mercury Capri?
A B78-13 tire for a 1979 Mercury Capri should first be chosen on fitment accuracy, since that size belongs to a specific 13-inch four-cylinder application. After confirming that B78-13 is the right primary size, the buyer can compare whether the goal is a traditional bias-ply presentation or a radial-equivalent alternative in a different sizing format.
That distinction affects both appearance and the overall direction of the tire setup. Keeping the original-style B78-13 format supports a more period-oriented look, while 175R13, P175/75R13, P185/70R13, or 650R13 may be evaluated as radial equivalents. The wheel width and available space around the tire should still be checked before settling on an alternative.
Restoration & Appearance
Which tire should I choose for a period-style 1979 Mercury Capri?
A period-style 1979 Mercury Capri tire choice starts with using the correct primary size for the exact sub-model. That could mean a 13-inch bias-ply fitment such as B78-13 or C78-13, a 14-inch radial fitment such as BR78-14 or CR78-14, or a 14-inch bias-ply C78-14 on a V8 application.
The key is to preserve the Capri's proper size family and construction type before thinking about alternatives. Buyers pursuing a restoration-oriented look should match the tire to the car's specific configuration and then use marque history, period photos, and vehicle-specific references if exact originality matters beyond general period-style fitment.
How does tire construction affect the appearance of a restored 1979 Mercury Capri?
Tire construction changes the visual impression of a restored 1979 Mercury Capri because bias-ply and radial tires do not present the same way even when they belong to related vintage size families. On this Capri, that difference is especially noticeable because some sub-models use primary bias-ply fitments while others use primary radial sizes.
A buyer trying to keep the car close to its original-era tire character should pay attention not just to wheel diameter, but also to whether the Capri was fitted for bias-ply or radial construction. That choice influences how authentic the finished stance and overall presentation feel, particularly on a restoration where details matter.
Fitment, Maintenance & Road Use
Can modifications affect tire fitment on a 1979 Mercury Capri?
Yes, modifications can affect tire fitment on a 1979 Mercury Capri. Even though the original applications already vary between 13-inch and 14-inch sizes, changes such as aftermarket wheels, altered wheel width, different offsets, lowered suspension, or body modifications can further change what clears the car properly.
That is why the actual setup on the car matters just as much as the original sub-model assignment. A Capri that now sits differently than stock may need extra attention to inner clearance, fender space, and steering sweep. Confirming those details before selecting a tire helps avoid choosing a size that belongs to the right Capri family but not the current build.
What should I inspect before driving a 1979 Mercury Capri on new tires?
Before driving a 1979 Mercury Capri on new tires, inspect the wheels for the correct diameter and sound condition, and make sure the tires are properly seated and inflated for initial use. It is also wise to look over suspension and steering components, especially on a collector-era car that may have spent long periods parked.
A short first drive should include attention to rubbing, steering feel, and any signs of uneven clearance during turns or suspension movement. After that, recheck pressure and give the tires another visual inspection. On a Capri with an older chassis or changed wheel setup, those simple checks can catch fitment issues before they become a larger problem.
How should tires on a collector 1979 Mercury Capri be maintained?
Tires on a collector 1979 Mercury Capri should be maintained with regular pressure checks, visual inspections, and attention to age-related deterioration as much as tread wear. Cars that are driven infrequently can still develop sidewall cracking, flat spotting, bulges, cuts, or slow air loss even when the tread looks serviceable.
Storage conditions also matter on a low-use Capri. Keeping the car away from prolonged sunlight, heat, moisture, and ozone sources helps protect the tire casing over time. Periodic inspection is especially important before longer drives, since a collector vehicle can appear ready for the road while its tires have aged beyond what a quick glance reveals.
