The 1977 Mercury Bobcat belongs to the compact-car era when American small cars were expected to balance easy maneuverability, economy, and everyday practicality. Whether in Runabout Base or Wagon form, the Bobcat carried that late-1970s character into a size and tire package that feels distinct from earlier full-size domestic cars. For this model year, the 1977 Mercury Bobcat uses BR70-13 or BR78-13 radial tires on 13-inch rims. That means the main decision is not bias-ply versus radial, but confirming the exact size on the car and choosing the right profile for appearance, stance, and wheel compatibility. Careful wheel and clearance checks matter even more if the car has been modified over the years.
Which Tire Size Is Right for The 1977 Mercury Bobcat
The 1977 Mercury Bobcat uses two primary tire sizes, BR70-13 and BR78-13, and both are radial sizes for 13-inch wheels. Because the same two sizes appear across the covered sub-models, the first step is confirming which size is actually on the car now by checking the wheel setup, existing tire marking, and available clearance before choosing between the two profiles.
BR70-13 is a vintage alphanumeric radial size. The letter-and-number combination identifies the tire's size class and profile family, while the R indicates radial construction and the 13 identifies a 13-inch rim. On a 1977 Mercury Bobcat, this size suits buyers who want to stay with a period-style radial format that matches the car's compact late-1970s character. It is worth evaluating when the goal is to keep the car on the smaller of its two primary radial fitments, but wheel width, current stance, and body clearance should still be confirmed on the actual vehicle.
BR78-13 is also a vintage alphanumeric radial size. In this format, the letter marks the tire's size class, the 78 identifies its profile family, the R denotes radial construction, and the 13 indicates a 13-inch rim diameter. For a 1977 Mercury Bobcat, this size represents the alternate primary radial fitment used within the same wheel diameter. It should be considered only after confirming which of the two primary sizes matches the car's present wheel and tire setup, especially on cars that may have seen wheel, suspension, or ride-height changes over time.
Tire fitment for the 1977 Mercury Bobcat is fairly straightforward because the covered sub-models share the same two radial size choices. Checking the exact sub-model still helps keep the selection process organized, especially when the car's current wheels or tire profile may not match its original-style setup.
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1977 Mercury Bobcat Runabout Base
The 1977 Mercury Bobcat Runabout Base uses the same two 13-inch radial fitments found elsewhere in the Bobcat range. That makes the key decision less about trim-specific tire construction and more about confirming whether BR70-13 or BR78-13 is the better match for the car's current wheel and clearance setup.
The 1977 Mercury Bobcat Wagon also uses the same pair of 13-inch radial sizes. Tire selection comes down to verifying which of the two primary fitments belongs on the wagon's current wheels and making sure the chosen profile works with the vehicle's ride height and fender clearance.
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
Owners usually want to confirm whether BR70-13 or BR78-13 belongs on their 1977 Mercury Bobcat, how those vintage radial sizes should be interpreted, and what to inspect on a compact collector car before putting it back on the road.
Tire Size & Fitment
What tire size fits a 1977 Mercury Bobcat?
A 1977 Mercury Bobcat uses one of two primary tire sizes: BR70-13 or BR78-13. Both are radial tires in a vintage alphanumeric format, and both mount on 13-inch rims. The covered Bobcat sub-models share those same two fitment choices rather than using different constructions or different wheel diameters.
The practical next step is confirming which of those two sizes belongs on the specific car in front of you. Check the tire size already fitted, confirm the wheel diameter, and look at overall clearance around the fenders and suspension, especially if the Bobcat has had wheel, suspension, or ride-height changes over the years.
What size rim does a 1977 Mercury Bobcat use?
The 1977 Mercury Bobcat uses a 13-inch rim with its primary tire fitments. Both BR70-13 and BR78-13 are built around that same rim diameter, so the difference between the two sizes is not wheel diameter but the tire's alphanumeric sizing profile within the same 13-inch wheel family.
That makes rim-diameter verification simpler, but it does not remove the need to check the actual wheels on the car. Many older compact cars have been changed over time, so it is smart to confirm the wheel's true diameter and width before selecting a tire, rather than assuming every 1977 Bobcat still has its original-style wheel setup.
Do all 1977 Mercury Bobcat sub-models use the same tire size?
The covered 1977 Mercury Bobcat sub-models use the same two tire sizes: BR70-13 and BR78-13. Both the Runabout Base and the Wagon share those radial fitments, so there is no split here where one sub-model uses a completely different construction type or a different rim diameter.
Even with that shared fitment, the exact tire choice still needs to match the car's present configuration. Looking at the current tire marking, measuring the wheel, and checking clearance can help confirm whether BR70-13 or BR78-13 is the right direction, particularly on cars that have seen years of maintenance changes or aftermarket updates.
Choosing the Right Tire
What should I consider when choosing a BR70-13 tire for a 1977 Mercury Bobcat?
Start by confirming that BR70-13 is the size your 1977 Mercury Bobcat actually uses, since BR78-13 is also a primary fitment for this model year. BR70-13 is a vintage alphanumeric radial size for a 13-inch rim, so the choice centers on staying with the proper size format and matching the tire to the car's wheel setup.
Once the size is confirmed, focus on how the car will be used and presented. A Bobcat kept close to a period-style appearance may call for one approach, while a driver with altered wheels or suspension may need closer attention to wheel width, profile, and available clearance before settling on a BR70-13 tire.
What should I consider when choosing a BR78-13 tire for a 1977 Mercury Bobcat?
Choosing a BR78-13 tire begins with making sure that BR78-13, not BR70-13, is the correct primary fitment for the specific 1977 Mercury Bobcat. It is a vintage alphanumeric radial for a 13-inch wheel, so the key is preserving the correct size relationship rather than simply picking any tire that fits the rim.
A careful comparison of the car's current wheels, tire markings, and available space in the wheel openings is worthwhile before making the final decision. That matters even more on a Bobcat that may no longer sit at stock ride height or may have aftermarket wheels that change how either primary size works on the car.
How do I choose between the available primary tire sizes for a 1977 Mercury Bobcat?
The right choice depends on whether your 1977 Mercury Bobcat is set up for BR70-13 or BR78-13. Both are proper primary radial fitments on 13-inch rims, so this is not a question of bias-ply versus radial but of identifying which alphanumeric size matches the car's wheel and tire package.
Reading the existing sidewall, confirming the wheel diameter, and checking the car's present stance usually point you in the right direction. A Bobcat that has remained close to its original-style setup may be easier to sort out, while one with changed wheels or suspension calls for a closer look at clearance before selecting either size.
Restoration & Appearance
Which tire should I choose for a period-style 1977 Mercury Bobcat?
A period-style 1977 Mercury Bobcat is best approached by staying within its primary vintage radial fitments, BR70-13 or BR78-13, depending on the car's actual setup. Both are alphanumeric radial sizes that suit the compact late-1970s look more naturally than a modern tire format that changes the car's visual character.
The best restoration-oriented choice is the one that matches the Bobcat's wheel diameter, profile, and intended presentation without forcing a size change. When exact originality matters, it is smart to compare the current car against marque references or historical documentation so appearance decisions support the restoration rather than just approximate it.
Does correct tire fitment matter for a 1977 Mercury Bobcat restoration?
Correct tire fitment matters on a 1977 Mercury Bobcat restoration because tire size affects both the car's appearance and how convincingly the finished vehicle reflects its era. Using BR70-13 or BR78-13 keeps the restoration conversation centered on the Bobcat's actual primary fitments rather than on a generic modern substitute.
Fitment also shapes practical details such as wheel compatibility and visible proportion within the wheel opening. A restoration-minded owner should confirm the rim diameter, verify what size the car is set up to use, and avoid assuming that any 13-inch tire will present the same way on the finished vehicle.
Fitment, Maintenance & Road Use
Can modifications affect tire fitment on a 1977 Mercury Bobcat?
Yes, modifications can affect tire fitment on a 1977 Mercury Bobcat even when the car stays within its primary 13-inch wheel diameter. Changes such as aftermarket wheels, altered wheel width, suspension work, lowering, or body adjustments can influence which of the two primary sizes, BR70-13 or BR78-13, works more cleanly on the car.
That is why it helps to inspect the actual vehicle instead of relying only on model-year fitment. Clearance at full steering lock, space near suspension components, and the relationship between the tire and fender opening all deserve a look before replacing tires on a Bobcat that may no longer match its original-style configuration.
What should I inspect before driving a 1977 Mercury Bobcat on new tires?
Before driving a 1977 Mercury Bobcat on new tires, inspect the wheels, valve stems, lug hardware, and the basic condition of the suspension and steering components. It is also wise to verify that the new tires match the car's correct primary size, either BR70-13 or BR78-13, and that there is no interference at the wheel openings.
A short post-installation check can prevent surprises on the road. Look for proper air retention, listen for rubbing during low-speed turns, and recheck visual clearance once the car is resting at normal ride height. Collector cars that have sat for long periods benefit from a careful shakedown rather than an immediate long-distance drive.
How should BR70-13 or BR78-13 tires on a collector 1977 Mercury Bobcat be maintained?
BR70-13 or BR78-13 tires on a collector 1977 Mercury Bobcat should be maintained with regular pressure checks, routine visual inspection, and attention to age-related deterioration. Because many older Bobcats see limited use, sidewall cracking, flat spotting, cuts, bulges, and slow air loss can become more important than tread wear alone.
Storage conditions matter as much as mileage on a lightly used compact collector car. Keeping the Bobcat away from prolonged heat, direct sunlight, moisture, and ozone sources helps preserve tire condition, and periodic inspection before each driving season can catch problems early before they affect road manners or reliability.
