The 1973 Subaru GL came from an era when small imported cars were winning buyers with compact dimensions, light weight, and everyday practicality rather than excess size or horsepower. For owners today, that modest early-1970s character makes correct tire selection especially important, because the tire has a big influence on stance, steering feel, and overall presentation. This model uses 13-inch fitments that include both period bias-ply 6.15-13 and radial sizes 155R13 or 145R13, depending on the specific version. Available choices stay close to the car’s original scale with blackwall radial options from brands such as Michelin, Dunlop, and Firestone. The key is confirming the exact sub-model and deciding whether originality, road manners, or period appearance comes first.
Which Tire Size Is Right for The 1973 Subaru GL
The 1973 Subaru GL uses three primary tire sizes across its covered configurations, all on 13-inch rims. Fitment varies by sub-model and by construction, so the first step is identifying whether the car is a GL Coupe or GL Coupe (Stage 1), then deciding whether a period-style bias-ply tire or a radial fitment matches the car’s current setup and intended use.
155R13 is a Euro-metric radial size with a nominal section width of 155 millimeters, radial construction, and a 13-inch rim diameter; in this format, the aspect ratio is not stated. On the 1973 Subaru GL, it represents a modernized radial-style fitment for the Coupe. Product choices in this size include blackwall offerings from Michelin and Dunlop, with tire series such as Michelin XAS-FF and SP Sport Aquajet. This size suits buyers who want to keep the correct overall format for the Coupe while comparing brand character and product details within a radial construction.
6.15-13 is a numeric bias-ply size in which the leading number indicates the nominal section width in inches, while the final number identifies a 13-inch rim. For the 1973 Subaru GL, this is the traditional bias-ply fitment shared across both covered sub-models, making it important for owners pursuing an earlier driving feel or a more period-style presentation. Bias-ply construction also changes the tire-selection conversation compared with the radial options used elsewhere on this model. This size is the one to evaluate carefully when the goal is to stay close to the car’s original-era tire character.
145R13 is a Euro-metric radial size with a nominal section width of 145 millimeters and a 13-inch rim diameter, with no aspect ratio stated in the size code. On the 1973 Subaru GL, it applies to the GL Coupe (Stage 1) as the radial fitment rather than the standard Coupe’s 155R13 radial. Available blackwall options include Michelin XAS-FF and Firestone F560 Radial, giving buyers a choice between different radial series in the correct size family. This size matters most when the Stage 1 designation is confirmed and the car retains its proper 13-inch wheel setup.
Sub-model identification matters on the 1973 Subaru GL because the two covered versions do not share the same radial size, even though both can use the same 6.15-13 bias-ply fitment. Confirming the exact Coupe designation keeps the tire search focused on the right primary size and construction path.
1
1973 Subaru GL Coupe
The 1973 Subaru GL Coupe uses 155R13 as its radial fitment and 6.15-13 as its bias-ply alternative. That gives the buyer a clear choice between staying with a period-style bias-ply presentation or selecting a correctly sized 13-inch radial in the Coupe’s proper width range.
The 1973 Subaru GL Coupe (Stage 1) uses 145R13 for radial fitment, while 6.15-13 remains the shared bias-ply size. That distinction makes the Stage 1 name especially important, because choosing between 145R13 and 155R13 changes the car’s intended fitment direction before product selection even begins.
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.
Best 1973 Subaru GL Tires for Sale
Available 13-inch Subaru GL tires center on blackwall radial choices from Michelin, Dunlop, and Firestone. The main comparison points are size, brand, tire series, radial construction details, and in some cases rim-width compatibility within the correct Coupe or Stage 1 fitment.
Owners of a 1973 Subaru GL usually need to sort out sub-model-specific tire size, 13-inch rim fitment, bias-ply versus radial choices, and which available blackwall tires best match restoration goals or regular road use.
Tire Size & Fitment
What tire size fits a 1973 Subaru GL?
The 1973 Subaru GL uses 155R13, 145R13, or 6.15-13 depending on the exact sub-model and construction choice. The GL Coupe uses 155R13 as its radial fitment and 6.15-13 as its bias-ply fitment, while the GL Coupe (Stage 1) uses 145R13 as its radial fitment and also shares the 6.15-13 bias-ply size.
That means the first step is confirming whether the car is a Coupe or a Coupe (Stage 1). Once that is clear, tire choice becomes a matter of staying with the proper radial size for that version or selecting the shared bias-ply size for a more traditional setup on the same 13-inch wheel diameter.
What size rim does a 1973 Subaru GL use?
The tire fitments covered for the 1973 Subaru GL all use a 13-inch rim diameter. That applies to the radial sizes 155R13 and 145R13 as well as the numeric bias-ply size 6.15-13, so wheel diameter remains consistent even though the tire sizing systems differ.
Rim diameter consistency helps narrow the search, but it does not make every tire automatically interchangeable between sub-models. A buyer still needs to confirm the exact Coupe version, then compare the actual tire size and, where available, the wheel-width suitability before moving from one radial size or construction type to another.
Do all 1973 Subaru GL sub-models use the same tire size?
No. Both covered 1973 Subaru GL sub-models share the 6.15-13 bias-ply size, but they do not share the same radial size. The GL Coupe uses 155R13 as its radial fitment, while the GL Coupe (Stage 1) uses 145R13.
That difference matters because a car identified only as a 1973 Subaru GL still needs the sub-model confirmed before ordering radial tires. Using the correct size keeps the tire proportion closer to the intended setup, while the shared 6.15-13 bias-ply size gives both versions a common period-style option on a 13-inch rim.
Bias-Ply & Radial Options
Is 6.15-13 a bias-ply or radial tire for the 1973 Subaru GL?
6.15-13 is the bias-ply tire size used on the 1973 Subaru GL. It is the shared bias-ply fitment for both the GL Coupe and the GL Coupe (Stage 1), while the radial fitments are 155R13 for the Coupe and 145R13 for the Stage 1.
That makes 6.15-13 the key size for owners who want a traditional construction rather than a radial setup. The practical decision is less about rim diameter, since all of these use 13-inch wheels, and more about whether the car is being kept in a period-style tire format or set up around its sub-model-specific radial size.
Should I use bias-ply or radial tires on a 1973 Subaru GL?
A 1973 Subaru GL can be set up with either its covered bias-ply fitment or its covered radial fitment, depending on the exact sub-model and the owner’s goals. The common bias-ply size is 6.15-13, while the radial sizes are 155R13 for the GL Coupe and 145R13 for the GL Coupe (Stage 1).
Bias-ply and radial choices usually come down to period appearance, driving feel, and how the car is intended to be used. Before changing construction, confirm the wheel setup, make sure the chosen size matches the correct sub-model, and check for adequate clearance if the car has been altered from its stock-era configuration.
What should I check before converting my 1973 Subaru GL from bias-ply to radial tires?
Start by confirming the exact sub-model, because the 1973 Subaru GL does not use one universal radial size. The GL Coupe uses 155R13 as its radial fitment, while the GL Coupe (Stage 1) uses 145R13, and both share 6.15-13 only on the bias-ply side.
After that, verify that the wheels are still 13-inch units suited to the selected radial size and compare the tire against the car’s current wheel width and available clearance. It also helps to inspect suspension and steering components first, since worn parts can make any construction change harder to evaluate on a light early Subaru.
Choosing the Right Tire
What should I consider when choosing a 1973 Subaru GL tire?
Start with the exact sub-model and the correct primary size. A 1973 Subaru GL Coupe calls for either 155R13 radial or 6.15-13 bias-ply, while the GL Coupe (Stage 1) uses 145R13 radial or the same 6.15-13 bias-ply size, so the right choice begins with fitment, not brand preference.
Once size and construction are settled, compare the tire’s intended look and use. Some owners want a blackwall radial that keeps the car road-friendly, while others want the more traditional presentation of a bias-ply tire. Rim-width suitability, load figures where stated, and the overall condition of the car’s wheel setup also deserve attention.
What sidewall styles are available for 1973 Subaru GL tires?
The available radial tires for the 1973 Subaru GL are blackwall tires. That applies across the covered 145R13 and 155R13 product choices, including Michelin, Dunlop, and Firestone offerings, so the visible sidewall presentation stays clean and understated rather than moving into whitewall or raised-letter territory.
For many early compact imports, that simple blackwall look suits the car’s proportions and avoids overpowering a small 13-inch wheel and tire package. Buyers focused on appearance should still match the sidewall treatment to the car’s overall restoration direction, then choose the correct size and construction for the exact Coupe version first.
What brands offer tires for the 1973 Subaru GL?
Michelin, Dunlop, and Firestone all offer applicable radial tires for the 1973 Subaru GL. Michelin appears in both 155R13 and 145R13 fitments through the XAS-FF series, Dunlop offers the SP Sport Aquajet in 155R13, and Firestone offers the F560 Radial in 145R13.
Brand choice only matters after the correct size is confirmed for the specific Coupe version. From there, compare each tire’s series, construction, blackwall presentation, and any stated wheel-width or load details that apply, rather than assuming that every brand’s 13-inch tire serves the same Subaru GL configuration.
Restoration & Appearance
Which tire should I choose for a period-style 1973 Subaru GL?
For a period-style 1973 Subaru GL, the shared 6.15-13 bias-ply fitment is the natural place to begin because it reflects the earlier sizing and construction approach used on this car. The radial alternatives, 155R13 for the Coupe and 145R13 for the Coupe (Stage 1), move the tire choice toward a more later-service style setup.
The best direction depends on whether the goal is an earlier visual presentation or a radial-equipped driver. Buyers pursuing exact historical authenticity should confirm the car’s original delivery configuration through marque-specific references, but the practical first step remains choosing the correct sub-model and staying within its proper 13-inch fitment family.
How does tire construction affect the appearance of a restored 1973 Subaru GL?
Tire construction changes more than road feel on a restored 1973 Subaru GL; it also influences the car’s visual character. A 6.15-13 bias-ply tire gives the Subaru a more traditional small-car presentation, while the radial options in 155R13 or 145R13 create a look associated with later replacement practice on compact imports.
That visual difference matters because the Subaru GL is a small, lightly styled car whose tire shape is easy to notice. Restorers should decide early whether the project leans toward period flavor or driver-oriented practicality, then keep the size matched to the correct Coupe or Coupe (Stage 1) designation.
Fitment, Maintenance & Road Use
Can modifications affect tire fitment on a 1973 Subaru GL?
Yes. Modifications can affect tire fitment on a 1973 Subaru GL even when the wheel still appears to be the correct 13-inch diameter. Changes such as aftermarket wheels, altered wheel width, suspension work, lowering, or body clearance changes can influence whether the intended 145R13, 155R13, or 6.15-13 setup remains appropriate.
A modified car should be checked as it sits rather than assumed to match stock-era tire space. Measure the existing wheel, inspect inner and outer clearance, and verify steering travel before changing sizes or construction types, especially when moving between the sub-model-specific radial sizes and the shared bias-ply fitment.
What should I inspect before driving a 1973 Subaru GL on new tires?
Before driving a 1973 Subaru GL on new tires, inspect the wheels, lug hardware, valve stems, and the general condition of the suspension and steering components. It also makes sense to confirm that the tire size matches the car’s exact sub-model, since the Coupe and Coupe (Stage 1) do not share the same radial fitment.
Tire condition remains important even when the tires are newly mounted. Check inflation, make sure there is no rubbing at full steering lock, and look over brake and wheel-bearing condition on a car that may have spent long periods parked. Early compact collector cars benefit from a slow, careful first road test.
How should tires on a collector 1973 Subaru GL be maintained?
Tires on a collector 1973 Subaru GL should be kept properly inflated, inspected regularly for cracking, cuts, bulges, uneven wear, and air loss, and protected from long exposure to sunlight, moisture, and ozone sources. That advice applies whether the car is running 6.15-13 bias-ply tires or the radial 145R13 or 155R13 fitments.
Low-mileage collector cars often age their tires out before they wear them out, so condition matters as much as tread depth. Periodic checks of wheel balance, alignment, and storage conditions help preserve ride quality and appearance, while a pre-drive inspection is especially wise after the car has been sitting for extended periods.
