1978 Subaru GL Tires

The 1978 Subaru GL uses two primary tire sizes: 155R13 in radial construction and 6.15-13 in bias-ply construction. Both sizes are associated with this model and both use a 13-inch rim, so the correct choice depends on which tire setup the car is using rather than on a different wheel diameter.

That means the first step is confirming whether the car is staying with a bias-ply arrangement or being fitted with the radial-size option. If the wheels, suspension, or ride height have been changed over the years, it is smart to verify actual wheel width, tire clearance, and the overall condition of the setup before selecting a replacement tire.

The 1978 Subaru GL uses a 13-inch rim diameter with both of its primary tire sizes. The radial 155R13 and the bias-ply 6.15-13 are both intended for 13-inch wheels, which simplifies the diameter question even though the car has two different tire constructions associated with it.

Rim diameter is only part of the fitment picture, so it still helps to check the wheel itself before mounting new tires. Collector cars sometimes end up with replacement wheels, and a mismatch in wheel width or an altered suspension can affect how a tire sits on the rim and how much clearance it has during steering and suspension movement.

The 1978 Subaru GL Coupe follows the same fitment pattern and can use either 155R13 radial tires or 6.15-13 bias-ply tires. There is no separate coupe-only tire size in this coverage, so the fitment question remains centered on construction choice rather than on a different sub-model size.

That makes the coupe owner’s decision fairly straightforward: determine which tire type is actually on the car or which direction the car is being restored toward. A buyer looking for a more traditional appearance may lean toward the bias-ply format, while someone keeping the radial-size setup should confirm wheel compatibility and compare available radial tire options in 155R13.

6.15-13 is the bias-ply tire size associated with the 1978 Subaru GL. Its numeric format is typical of vintage bias-ply sizing, with the 6.15 figure indicating nominal section width and the 13 showing the wheel diameter in inches.

Choosing this size keeps the car in a traditional construction format rather than moving to the radial-size alternative. That matters for owners who care about period-style appearance and setup consistency, but the wheel itself should still be checked for diameter, condition, and suitability before mounting a new tire, especially if the car has had wheels replaced at some point.

155R13 is the radial tire size used on the 1978 Subaru GL. In this size format, 155 is the nominal width in millimeters, the R identifies radial construction, and 13 is the rim diameter, so it represents a distinctly different construction path from the 6.15-13 bias-ply option.

That distinction matters because a radial-size setup affects tire choice, wheel compatibility, and the overall presentation of the car. Owners considering 155R13 should make sure the vehicle is actually set up for that size and compare available radial products carefully, including rim-width requirements and any changes made to the wheels or suspension over the years.

A 1978 Subaru GL can be approached from either direction because both a 6.15-13 bias-ply size and a 155R13 radial size are associated with this model. The better choice depends on whether the goal is to preserve a more traditional presentation or maintain the car around its radial-size configuration.

Appearance, driving expectations, and the actual wheel setup should guide that decision. A bias-ply choice may suit a restoration-oriented approach, while a radial setup may appeal to owners keeping the car in radial form for regular road use. Before changing construction, check wheel condition, tire clearance, and any modifications that might affect how the new tires sit on the car.

Start with the correct primary size and construction for the car’s setup: either 155R13 in radial form or 6.15-13 in bias-ply form. After that, compare practical factors such as wheel compatibility, intended use, and whether the goal is a traditional restoration-oriented look or a period-style radial presentation.

The available 155R13 products also show that brand, tire series, and specification details can matter within the same size. A buyer should look at rim-width suitability where stated, load information when available, and the overall character of the tire rather than treating all same-size options as interchangeable in appearance or setup requirements.

For the 1978 Subaru GL’s 155R13 radial size, available products include Michelin and Dunlop. Those brands appear in period-oriented offerings such as Michelin XAS-FF and Dunlop SP Sport Aquajet, giving buyers more than one route within the same basic radial fitment.

Brand choice should be treated as one part of the selection process rather than the whole answer. It still helps to compare the specific tire series, blackwall presentation, and any stated rim-width or load details so the selected tire matches the car’s intended use and the wheel setup actually on the vehicle.

The available 155R13 radial products for the 1978 Subaru GL use a blackwall sidewall style. That gives the car a clean, understated presentation that fits many compact import restorations and preserved drivers without adding a more decorative stripe or raised-letter appearance.

Sidewall style is partly an appearance decision, but it should still be made after the correct size and construction are settled. Once those basics are confirmed, blackwall options can be compared by brand and series to find a tire that suits the way the car is being presented, whether that means a careful restoration or a tidy road-going vintage Subaru.

A period-style 1978 Subaru GL can be approached with either the 6.15-13 bias-ply size or the 155R13 radial size, depending on the presentation and setup being preserved. The bias-ply route emphasizes a more traditional vintage tire format, while the radial route keeps the car in the radial-size pattern associated with this model.

The right choice depends on how closely the car is being restored and what look the owner wants to maintain. When exact historical accuracy matters, marque references, original literature, and vehicle-specific restoration guidance are worth checking before settling on construction, since a period-style tire is not automatically the same thing as a factory-original tire choice.

Tire construction changes more than the internal build of the tire; it also influences how a restored 1978 Subaru GL presents visually. A 6.15-13 bias-ply setup gives the car a more traditional vintage look, while a 155R13 radial keeps it in a later-style compact-car sizing format that still feels appropriate to the period.

That visual difference matters on a small car because the tire contributes noticeably to stance and overall character. Owners should decide early whether the restoration is centered on an earlier-looking bias-ply presentation or a radial-era look, then make sure the chosen size works with the wheels on the car and the way the Subaru is meant to be shown or driven.

Yes, modifications can affect tire fitment on a 1978 Subaru GL even when the tire size itself is correct. Aftermarket wheels, changes in wheel width, suspension alterations, lowering, or body repairs can all influence how a 155R13 or 6.15-13 tire sits in the wheel opening and how much clearance it has in use.

That is why fitment should be checked on the actual car, especially with an older vehicle that may have changed hands several times. Steering clearance, fender space, and wheel condition all deserve attention before a new tire is mounted, and any deviation from the original-style setup makes those checks even more important.

Before driving a 1978 Subaru GL on new tires, inspect the wheels for correct diameter and general condition, and make sure the tires are seated properly and inflated appropriately for the application. It also helps to check for any rubbing at the fenders or suspension, especially if the car has been modified or has replacement wheels.

A broader walk-around is worthwhile on any vintage Subaru that has seen limited use. Look for aging issues elsewhere in the chassis, confirm that steering and suspension components are in sound condition, and recheck the tires after the first short drive for air retention and clearance so the car is ready for more regular road use.

Tires on a collector 1978 Subaru GL should be inspected regularly for cracking, bulges, cuts, abnormal wear, and slow air loss, even if the car is driven only occasionally. Vintage cars often spend long periods parked, so tire age and storage conditions can matter just as much as tread depth.

Pressure checks, periodic movement of the car, and storage away from prolonged sunlight, moisture, and ozone sources all help preserve tire condition. It is also smart to look over the wheels and suspension at the same time, because a well-maintained tire can still be affected by alignment issues, worn components, or a wheel that no longer matches the intended setup.