The 1958 Austin A 105 sits in an interesting place in British motoring, combining the upright sedan character of the late 1950s with a six-cylinder identity that gives it appeal among collectors today. Tire choice matters here because this car can be fitted with either a 640-15 bias-ply tire or a 185R15 radial, both on 15-inch rims. That opens two very different paths: a more traditional bias-ply presentation or a radial setup in a classic Euro-metric size, with choices that include blackwall, whitewall, and redline styling. The right direction depends on how original-looking, road-oriented, or restoration-focused the car needs to be.
Which Tire Size Is Right for The 1958 Austin A 105
The 1958 Austin A 105 uses two primary tire sizes, and the key distinction is construction rather than wheel diameter since both fit a 15-inch rim. One option is the traditional 640-15 bias-ply size, while the other is a 185R15 radial. The first step is deciding whether the car should stay with a period-style bias-ply fitment or move to a radial in the proper 15-inch size, then checking wheel width and overall vehicle setup.
185R15 is a Euro-metric radial size in which 185 represents the nominal section width in millimeters, R indicates radial construction, and 15 is the rim diameter in inches. On the 1958 Austin A 105, this size represents the radial path and gives access to several classic-style tire choices on the correct 15-inch wheel. Available options include Coker Classic, Michelin, Avon, and Universal Vintage Tire, with blackwall, narrow whitewall, and redline sidewall treatments across series such as Michelin XVS, Coker Classic Radial, Universal Sport, and Turbosteel CR3B. It is the size to evaluate when radial construction is the priority but traditional visual character still matters.
640-15 is a numeric bias-ply size in which 640 refers to an approximate 6.40-inch nominal section width and 15 identifies the rim diameter. For the 1958 Austin A 105, this is the traditional bias-ply fitment and the natural starting point for an owner who wants a more period-style construction and profile. Product choices include BFGoodrich, Firestone, Avon, and Excelsior, with blackwall, narrow whitewall, and wide whitewall versions offered through series such as Firestone Classic Bias Ply, Silvertown Classic Bias Ply, Super Safety Crossply, and Excelsior Bias Ply. It is the size to consider when original-era tire character and sidewall presentation are central to the car’s look.
Fitment is straightforward across the covered 1958 Austin A 105 sub-model because the same two 15-inch tire sizes apply. Checking the exact sub-model still matters so the tire choice stays aligned with the car’s wheel setup and the owner’s preference for bias-ply or radial construction.
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1958 Austin A 105 Six
The 1958 Austin A 105 Six uses the same two primary tire paths found on this model line: 640-15 in bias-ply construction or 185R15 in radial form. That gives the owner a clear choice between a more traditional period-style tire presentation and a radial alternative with several available sidewall and brand options.
Bias-Ply to Radial Tire Conversion for the 1958 Austin A 105
For the original 640-15 tire size, three radial-equivalent options are available. 175R15 is the 80-series metric radial equivalent, P175/75R15 is the P-metric 75-series radial equivalent, and P185/70R15 is the P-metric 70-series radial equivalent. These choices vary by sizing convention and profile approach rather than serving as automatic substitutions. A recommended rim-width range of 5 to 6 inches is associated with these equivalents, so wheel width, overall dimensions, and vehicle clearance should be checked before making the change.
Modern Radial Equivalents
175R15
Equivalent 80-series Metric Radial (640-15)
P175/75R15
Equivalent P-metric 75-series Radial (640-15)
P185/70R15
Equivalent P-metric 70-series Radial (640-15)
Important Considerations When Replacing Bias Ply With Radial
Compare overall diameter and section width carefully to ensure proper fit.
Verify recommended rim range (5-6 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.
Best 1958 Austin A 105 Tires for Sale
Available tires for the 1958 Austin A 105 span both 640-15 bias-ply and 185R15 radial fitments, with brands including BFGoodrich, Firestone, Michelin, Avon, Excelsior, Coker Classic, and Universal Vintage Tire. The main points of comparison are construction, tire series, sidewall style, and rim-width compatibility.
These FAQs focus on the actual tire choices for the 1958 Austin A 105, including 640-15 versus 185R15 fitment, 15-inch rim considerations, radial equivalents, sidewall styling, and the checks that matter before road use.
Tire Size & Fitment
What tire size fits a 1958 Austin A 105?
The 1958 Austin A 105 uses two primary tire sizes: 640-15 in bias-ply construction and 185R15 in radial construction. Both sizes are 15-inch fitments, so the main difference is the tire type and sizing system rather than wheel diameter.
That means the real choice is not simply finding any 15-inch tire, but deciding whether the car should stay with a traditional bias-ply setup or use a radial alternative. Wheel width, overall tire dimensions, and the car’s current wheel and suspension setup should all be checked before settling on one size path.
What size rim does a 1958 Austin A 105 use?
The 1958 Austin A 105 uses a 15-inch rim with both of its primary tire sizes. That applies whether the car is running the 640-15 bias-ply size or the 185R15 radial size, so rim diameter remains consistent across the available fitments.
Rim diameter is only part of the fitment picture, though. Width still matters, especially when comparing bias-ply and radial tires, because the available products do not all share the same rim-width range. Measuring the actual wheel on the car is a smart step if it may have been changed during restoration or past service.
Does the 1958 Austin A 105 Six use the same tire size?
Yes. The 1958 Austin A 105 Six uses the same two primary tire sizes associated with this model: 640-15 as a bias-ply fitment and 185R15 as a radial fitment. Both are intended for 15-inch rims.
That keeps sub-model fitment simple, but the construction choice still affects the buying decision. An owner can focus on whether the goal is a more traditional period-style look with bias-ply tires or a radial setup with classic sidewall options, then confirm wheel width and clearance before installing a different construction type.
Bias-Ply & Radial Options
Is 640-15 a bias-ply or radial tire for the 1958 Austin A 105?
640-15 is a bias-ply tire size for the 1958 Austin A 105. It uses the older numeric sizing format and represents the traditional construction choice for this car, with available options in blackwall, narrow whitewall, and wide whitewall styles.
Choosing 640-15 usually means preserving a more period-style tire profile and appearance. That does not make every 15-inch wheel automatically suitable, since available products within this size still vary in rim-width specifications. The car’s existing wheels should be measured and matched to the intended tire before moving ahead.
What radial tire sizes are equivalent to 640-15?
Radial equivalents for 640-15 include 175R15, P175/75R15, and P185/70R15. Those cover three different radial sizing approaches: an 80-series metric radial, a 75-series P-metric radial, and a 70-series P-metric radial, all tied to the original 640-15 size.
These equivalents are comparison points rather than automatic substitutions. The recommended rim-width range associated with them is 5 to 6 inches, and the car should also be checked for wheel compatibility, tire clearance, and overall dimensions before conversion. That is especially important on a restored car that may no longer have its original wheel setup.
What should I check before converting my 1958 Austin A 105 from bias-ply to radial tires?
Start by confirming the wheel diameter and actual wheel width, then compare the intended radial size to the tire already on the car. For a 640-15 bias-ply setup, the radial alternatives include 175R15, P175/75R15, and P185/70R15, while 185R15 is also a primary radial fitment for the Austin A 105.
The next step is checking steering clearance, fender clearance, suspension condition, and how the car sits at normal ride height. A collector car can have wheel changes, worn bushings, or altered springs that affect fitment. Matching the tire to the actual car matters more than relying on size code alone.
Choosing the Right Tire
What should I consider when choosing a tire for a 1958 Austin A 105?
The first decision is whether the Austin A 105 should use its 640-15 bias-ply fitment or its 185R15 radial fitment. From there, the useful comparison points are sidewall style, tire series, brand, rim-width compatibility, and any load figures that matter for the way the car will be driven.
A restoration-oriented car may lean toward the visual character of a bias-ply tire, while a road-use car may be evaluated around the available radial offerings. It also helps to inspect the wheels already on the car, because not every product within these sizes uses the same wheel-width range.
What sidewall styles are available for 1958 Austin A 105 tires?
Tires for the 1958 Austin A 105 are available in blackwall, narrow whitewall, wide whitewall, and redline styles. Those sidewall choices appear across both of the vehicle’s fitment paths, with the 640-15 bias-ply size offering traditional blackwall and whitewall treatments, and the 185R15 radial size offering blackwall, narrow whitewall, and redline options.
Sidewall style shapes the car’s overall presentation as much as construction type does. A wide whitewall gives a distinctly late-1950s visual effect, while blackwall and redline treatments create a different character. The best choice depends on the look being pursued and on which tire size path the car is actually using.
What brands offer tires for the 1958 Austin A 105?
The 1958 Austin A 105 has tire options from BFGoodrich, Firestone, Michelin, Avon, Excelsior, Coker Classic, and Universal Vintage Tire. Those brands are spread across the two main fitments, with bias-ply choices in 640-15 and radial choices in 185R15.
Brand is only one part of the decision. It still makes sense to compare the tire series, sidewall treatment, construction type, and wheel-width compatibility within the correct size. Two tires may share the same nominal fitment but differ in appearance and wheel requirements, which matters on a carefully restored or regularly driven Austin.
Restoration & Appearance
Which tire should I choose for a period-style 1958 Austin A 105?
A period-style 1958 Austin A 105 usually starts with the 640-15 bias-ply fitment, because that size and construction preserve the traditional tire character associated with late-1950s cars. Within that size, blackwall, narrow whitewall, and wide whitewall versions create different visual moods without moving away from the bias-ply format.
The best selection depends on whether the goal is a broader restoration look or a specific historical presentation. If exact originality matters, marque references and period documentation are worth consulting before choosing a sidewall treatment. For many owners, the right answer is the tire that keeps the car visually consistent with its era.
How does tire construction affect the appearance of a restored 1958 Austin A 105?
Tire construction changes the visual character of a restored 1958 Austin A 105 in noticeable ways. A 640-15 bias-ply setup delivers a more traditional presentation, while a 185R15 radial gives the car a different stance and visual feel even when the sidewall styling remains conservative.
That difference is why construction should be treated as both a fitment choice and an appearance choice. A radial can still suit a restoration-minded car, especially with blackwall, narrow whitewall, or redline styling, but it does not present exactly like a bias-ply tire. The intended balance between road use and period character should guide the decision.
Fitment, Maintenance & Road Use
Can modifications affect tire fitment on a 1958 Austin A 105?
Yes. Modifications can affect tire fitment on a 1958 Austin A 105 even when the tire size itself is correct. Aftermarket wheels, changes in wheel width, altered ride height, suspension work, or body repairs can all change the space available for a 640-15 bias-ply or 185R15 radial tire.
That is why the actual car should be checked before changing size or construction. Turning clearance, fender clearance, and the relationship between the tire and suspension components matter just as much as the printed size code. A restored car may also have non-original wheels that change what rim-width range is appropriate.
What should I inspect before driving a 1958 Austin A 105 on new tires?
Before driving a 1958 Austin A 105 on new tires, inspect the wheels for damage, confirm the rim diameter and width, and make sure the tires are seated and inflated correctly. It also helps to check lug hardware, steering components, and basic suspension condition so the new tires are not being asked to compensate for unrelated problems.
A slow first road test is wise on any collector car, especially after changing from bias-ply to radial construction or moving to a different equivalent size. Watch for rubbing, vibration, pull, or uneven clearance at full steering lock. Catching those issues early helps protect both the tires and the car.
How should tires on a collector 1958 Austin A 105 be maintained?
Tires on a collector 1958 Austin A 105 should be checked regularly for pressure, tread wear, sidewall cracking, bulges, cuts, and slow air loss. Even a car that is driven only occasionally can develop tire problems from age, long static storage, or environmental exposure rather than simple mileage.
Storage conditions matter as much as inspection intervals. Keeping the car away from prolonged sunlight, excess heat, moisture, and ozone-producing equipment helps preserve the rubber. It also makes sense to inspect the tires before every meaningful drive, since collector cars often spend enough time parked for conditions to change between outings.
