By 1978, Subaru had established a clear identity around compact, efficient cars with practical packaging and a reputation for durability, and the DL and GL captured that character well. A buyer looking at 1978 Subaru fitment is usually dealing with two closely related model lines that share the same tire choices rather than a wide spread of model-specific sizes. Both models use two 13-inch fitments, with the real choice centering on whether you want a bias-ply tire for a more period-correct look and feel or a radial for more modern road manners. Before choosing a tire, confirm your model and decide whether originality or regular driving behavior matters more to your build.
Which Tire Size Is Right for Your 1978 Subaru
Two tire sizes are used across 1978 Subaru vehicles, and both the DL and GL share the same choices. Because both sizes mount on 13-inch wheels, the real decision is usually construction and driving character rather than basic model fitment. Understanding that distinction before choosing a product helps you narrow the right tire much faster.
Year(s): 1978|Fit(s): DL, GL|Construction: Radial|Rim: 13 in
155R13 is a metric radial size with a 155-millimeter section width and a 13-inch rim diameter, using the older Euro-metric convention that typically corresponds to an 80-series profile. This size is available from Michelin and Dunlop in Blackwall form, and the products here are radial designs with H speed ratings up to 130 mph; one is marked TL while another does not carry the same tube marking. For a 1978 Subaru driven regularly on modern roads, this is the more familiar modern-style choice in the year's shared 13-inch fitment.
6.15-13 is a numeric bias-ply size in which the first number expresses nominal section width in the traditional inch-based format and the final number is the 13-inch rim diameter. It represents the period-style bias-ply fitment shared by both the DL and GL. For a 1978 Subaru restored with an eye toward original-era appearance and driving feel, this size is the one that aligns with that older construction style.
Since both sizes use a 13-inch rim diameter, either can often work on the same wheels once actual rim width is confirmed.
1978 Subaru Models
Two Subaru models are covered for 1978: the DL and GL. They share the same tire sizes, so the key difference is not basic fitment but how closely you want the tire to match the car's original-era character versus a more modern radial driving feel. Select your model below for model-specific tire fitment history and products.
1978 Subaru DL
The 1978 Subaru DL was the simpler, value-oriented trim in Subaru's compact lineup, aimed at buyers who wanted economy and practicality in a small Japanese car. Its tire choices mount on 13-inch wheels, with one radial option and one bias-ply option depending on whether the goal is regular road use or a more period-style presentation.
The 1978 Subaru GL sat above the DL in trim and presentation, giving buyers a more upscale version of Subaru's compact formula without changing the underlying size family. Its tires also fit 13-inch wheels, so the decision comes down to radial versus bias-ply construction rather than a different wheel diameter.
Two products are available across two tire sizes for 1978 Subaru vehicles. The 155R13 radial is offered by Michelin and Dunlop in Blackwall form, while the 6.15-13 covers the year's bias-ply fitment. Confirm your preferred size and construction before selecting, since tube markings can vary by product.
These FAQs cover the two shared 1978 Subaru tire sizes, the difference between radial and bias-ply choices, 13-inch wheel compatibility, Blackwall product options, and the storage and inspection habits that matter on a lightly used collector car.
Size Basics & Fitment
What tire sizes fit 1978 Subaru vehicles?
1978 Subaru DL and GL models use two tire sizes: 155R13 and 6.15-13. Both sizes fit 13-inch rims, and both apply across the full 1978 Subaru model range covered here rather than being split by DL versus GL. For the radial 155R13, available products fit rim widths from 4.00 to 5.50 inches.
That means the first step is not sorting between DL and GL, but deciding whether you want a radial or a bias-ply tire. If your priority is original-era character, the bias-ply route will usually be the more authentic visual and driving match. If your Subaru will see more routine road use, the radial path is often the more natural place to start. Always confirm the actual wheel width before ordering.
What does 155R13 mean on a 1978 Subaru tire?
On a 1978 Subaru, 155R13 is an older Euro-metric radial size. The 155 refers to nominal section width in millimeters, the R identifies radial construction, and the 13 is the wheel diameter in inches. In this older metric format, the aspect ratio is typically understood as an 80-series profile even when it is not written out in the size code.
That makes 155R13 the more modern-construction option for a 1978 Subaru DL or GL while still keeping the car in its proper compact 13-inch tire family. If you are comparing it with 6.15-13, the biggest difference is not wheel diameter but tire construction and the way the car will feel on the road. It is a good choice to investigate first if your car is driven more than it is shown.
What does 6.15-13 mean on a 1978 Subaru tire?
On a 1978 Subaru, 6.15-13 is a traditional numeric bias-ply size. The 6.15 is the nominal section width expressed in the older inch-based naming system, and the 13 is the wheel diameter in inches. Unlike a radial metric code, it does not use an R and belongs to the earlier bias-ply style that remained familiar on many small cars from the period.
For a buyer, that usually signals an authenticity-focused fitment rather than a modernized one. The size still belongs to the same 13-inch wheel family used by the radial option, but it brings the visual stance and driving character associated with period bias-ply construction. If the goal is a restoration that looks and feels closer to the late 1970s, this is the size to research more closely.
Buying the Right Tire
Should I choose the 155R13 or the 6.15-13 for my 1978 Subaru?
For a 1978 Subaru, the choice between 155R13 and 6.15-13 is mainly a choice between radial and bias-ply construction. Both sizes fit the DL and GL and both use a 13-inch rim diameter, so this is not a matter of one size fitting one model and the other fitting a different model. The radial 155R13 is the more contemporary construction, while 6.15-13 reflects the older bias-ply approach.
That usually means 6.15-13 appeals more to restorations where original-era appearance and feel are a priority, while 155R13 makes more sense for owners who plan to spend more time driving the car on present-day roads. The right answer depends on how the Subaru will be used and judged. Once you have settled on that direction, verify your wheel width and then compare the available products within that size.
What sidewall styles are available for 1978 Subaru tires?
The 155R13 radial products for 1978 Subaru come in Blackwall form. Blackwall styling suits the compact, understated look many late-1970s import cars carried, especially on practical trims such as the DL and GL. It keeps the presentation clean and era-appropriate without introducing a more decorative sidewall treatment.
For a buyer trying to preserve the right look, sidewall appearance matters almost as much as size. A 1978 Subaru restored in stock fashion generally looks most natural with a plain black sidewall rather than a more stylized treatment. If visual authenticity is one of your goals, compare the sidewall appearance first and then choose the construction that best matches how the car will be used.
What brands make tires for 1978 Subaru vehicles?
1978 Subaru vehicles in 155R13 radial form are available from Michelin and Dunlop. Michelin appears here in the XAS family, while Dunlop covers the size with its SP Sport Aquajet line. Both are well-known names with long histories in period European and import-oriented radial tire development.
Brand choice matters most after you have settled on the correct size and construction. If you are staying with 155R13, compare the sidewall appearance, speed marking, and any tube designation on the specific tire you are considering. That approach keeps the decision centered on fitment and intended use instead of choosing a name first and trying to force the size question afterward.
Fitting & Setup
What rim width do 1978 Subaru tires require?
For 1978 Subaru vehicles using 155R13, the supported rim width range is 4.00 to 5.50 inches on a 13-inch wheel. That range covers the radial fitment used on both the DL and GL. The year's other tire size, 6.15-13, shares the same 13-inch rim diameter family.
Rim width is worth checking before you commit to a tire because two wheels with the same diameter are not always the same width. The safest path is to confirm the actual wheel on the car, especially if the Subaru has changed hands several times or has been restored with replacement wheels. Once the wheel width is known, you can choose your construction style with much more confidence.
Do 1978 Subaru tires require inner tubes?
Tube requirements on 1978 Subaru tires depend on the specific tire. Within the 155R13 radial choices, one tire is clearly marked TL for tubeless use, while another does not carry the same tube marking in its size designation. That means tube status can vary by product rather than being assumed across the entire size.
The wheel itself matters just as much as the tire marking, especially on an older car. Before installation, check the sidewall designation on the exact tire you choose and make sure the wheel condition and wheel type support that setup. If your Subaru still has original-style wheels, this is one area where a tire professional or marque specialist can help you avoid an incorrect assembly.
Can the original 1978 Subaru wheels be used with both tire sizes?
In most cases, the original 1978 Subaru wheels can be used with both tire sizes because 155R13 and 6.15-13 share the same 13-inch rim diameter. That common diameter is why both sizes appear across the DL and GL without requiring a model-specific wheel diameter change. The main remaining variable is wheel width, not wheel diameter.
That shared 13-inch fitment gives owners some flexibility when choosing between a more period-style bias-ply tire and a radial alternative. Even so, an older Subaru may no longer have its factory wheels, so a quick width check is still worthwhile before making the final choice. Treat wheel diameter as the first box to check and wheel width as the second.
Maintenance, Storage & Longevity
How should I store a 1978 Subaru when the tires are fitted?
A stored 1978 Subaru should be kept out of direct sunlight and away from ozone sources such as electric motors, battery chargers, welders, and furnace equipment. Clean, dry floors and stable temperatures help preserve the rubber, and the car should either be moved periodically or supported in a way that reduces long-term static loading. Bias-ply tires tend to flat-spot more readily in storage than radials, so that difference matters if your Subaru sits for long periods.
Good storage habits protect the tire as much as the car. Keep inflation checked during storage, avoid letting the tires sit under extra load, and inspect the sidewalls before bringing the car back into service. If your 1978 Subaru wears bias-ply tires for authenticity, expect a little more sensitivity to long stationary periods than you would with a radial setup.
How long do tires on a 1978 Subaru typically last?
On a 1978 Subaru, tire life is usually judged more by age than by miles, especially on collector or hobby-driven cars. A practical rule is to begin evaluating tires closely once they reach about five to seven years of service and to treat ten years as a point where replacement deserves serious consideration regardless of tread depth. The DOT date code on the tire sidewall is the starting point for that timeline.
That age-based approach matters because an older Subaru may wear very little tread while the rubber itself hardens, cracks, or loses flexibility. A car that only comes out for weekend drives is not exempt from aging. If you do not know when the tires were installed, confirm the date code first and use that information along with condition, storage history, and driving plans.
How often should tires on a 1978 Subaru be inspected?
Tires on a 1978 Subaru should be inspected before every drive and again before any longer outing. Look for sidewall cracking, cuts, bulges, irregular tread wear, low pressure, and any sign that the tire is not holding air consistently. If your chosen setup involves tube-type construction or mixed tube markings across products, valve stems and air retention deserve extra attention.
Frequent inspection is especially important on a small vintage car because tire issues can change the way the car tracks, steers, and brakes long before a complete failure occurs. A short walk-around takes only a minute and often catches problems early. On a longer trip, include the spare in the inspection so you are not relying on an aged or neglected backup.
Restoration & Authenticity
What tires were originally fitted to the 1978 Subaru DL?
A 1978 Subaru DL would have been associated with the era when bias-ply and radial fitments overlapped in the small-car market, which is why both 6.15-13 and 155R13 appear within the year's tire choices. Bias-ply construction was the older standard, while radial tires had become increasingly common by the late 1970s. The original factory fit could vary by market, equipment level, and production timing.
For a restoration, that means you should treat the year-make size range as the starting point and then confirm your specific car through original literature, surviving examples, or Subaru marque resources. Construction type, sidewall appearance, and size code all matter if the goal is authenticity. If your DL will be judged, event-specific standards are worth checking before you settle on radial versus bias-ply.
Does correct tire fitment matter for showing a 1978 Subaru?
Correct tire fitment does matter when showing a 1978 Subaru, especially if the event emphasizes factory-style presentation or preservation accuracy. Judges and knowledgeable enthusiasts often notice whether the size, construction type, and sidewall appearance fit the era and the character of the car. A modern-looking radial where a period-style bias-ply appearance is expected can stand out quickly on a carefully restored compact import.
That does not mean every show car must wear the same tire, but it does mean your tire choice should match the standard you are building toward. A driver-level Subaru can reasonably prioritize road use, while a concours-minded car should be researched more narrowly. Marque clubs and event rulebooks are the right places to confirm how closely originality is judged for your class.
Why would a restorer choose bias-ply tires for a 1978 Subaru instead of radial tires?
A restorer may choose bias-ply tires for a 1978 Subaru because bias-ply construction preserves the period look and driving character associated with earlier original-style fitment. The 6.15-13 size sits squarely in that tradition and keeps the car visually closer to what many late-1970s economy cars wore in base-era presentation. Radials such as 155R13 belong to the same general fitment family but reflect a more modern construction method.
The right choice depends on the goal of the restoration rather than on one construction being universally correct for every 1978 Subaru. If the car is built for authenticity, bias-ply often becomes the stronger visual match. If it is built to be driven more often, a radial may be more appealing while still keeping the car in an appropriate 13-inch size family.
Safety & Road Use
Are 1978 Subaru tires safe for highway driving?
1978 Subaru tires can be suitable for highway driving when the tire's condition, inflation, age, and speed rating all match the way the car is used. The 155R13 radial options here carry H speed ratings, which correspond to 130 mph. In real use, a 1978 Subaru's overall mechanical condition, braking capability, suspension health, and alignment are usually more important highway-limit factors than the tire's speed ceiling.
Safety comes from the whole package, not the size code alone. A fresh, correctly fitted tire on a well-sorted car is far more reassuring than an old tire with plenty of tread on a neglected chassis. Before regular highway use, verify the age of the tires, inspect the sidewalls, and make sure the car tracks straight and holds pressure properly at normal driving speeds.
What inflation pressure should I use for 1978 Subaru tires?
Inflation pressure for a 1978 Subaru should be set by the vehicle's factory recommendations and then checked against the tire manufacturer's own guidance for the exact tire you choose. One 155R13 radial here includes a maximum load capacity of 937 pounds, but that figure does not automatically become the day-to-day pressure setting for every 155R13 tire or for the 6.15-13 bias-ply size.
The important point is not to transfer pressure assumptions from one tire to another just because both fit a 13-inch wheel. Construction type, casing design, and intended use can change the proper operating pressure. Start with the vehicle recommendation, confirm the tire's sidewall markings, and make small adjustments only with a clear reason and consistent pressure checks.
What should I check before taking a 1978 Subaru on a longer drive?
Before a longer drive in a 1978 Subaru, inspect each tire for cracking, cuts, bulges, exposed cords, uneven wear, and proper inflation. Check that the valve stems are sound, and if your chosen tire setup involves tube-type construction or mixed tube markings across products, give air retention extra attention. The spare should also be usable, correctly inflated, and no older or rougher than the road tires if possible.
Tires are only one part of the pre-trip picture on a late-1970s car. It is equally wise to confirm brakes, steering, wheel bearings, and basic fluid condition before setting out. A compact Subaru in good tune is a very different experience from one that has been sitting, and a careful pre-drive inspection is the best way to keep a pleasant trip from becoming a roadside repair.
