The 1966 Austin A 40 belongs to the practical small-car tradition that made postwar British motoring so distinctive, blending compact dimensions with simple, usable engineering. Today, surviving A 40s appeal to owners who want an approachable vintage car with authentic period character on the road and at shows. Tire choice on this model centers on two 13-inch fitments: a 520-13 bias-ply option and a 145R13 radial option. That opens the door to different looks as well, including blackwall, narrow whitewall, and wide whitewall styles across Firestone, Michelin, and Premium Sport offerings. The right choice depends on whether the goal is traditional appearance, radial road manners, or a careful balance of both.
Which Tire Size Is Right for The 1966 Austin A 40
The 1966 Austin A 40 uses two primary tire sizes, both on 13-inch rims, with the choice split between a radial and a bias-ply construction. The key first step is confirming whether the car is set up for the 145R13 radial fitment or the 520-13 bias-ply fitment, since construction, appearance, and available tire styles differ meaningfully between them.
A 145R13 size uses a nominal section width of 145 millimeters, radial construction, and a 13-inch rim diameter. On the 1966 Austin A 40, this is the radial primary fitment and it suits owners who want a more modern tire format while staying within the proper general sizing family for the car. Available choices include blackwall radial options from Michelin and Firestone in the Michelin XAS-FF and F560 Radial series. It is the size to examine when the car is already running a radial setup and wheel compatibility remains within the proper 13-inch range.
A 520-13 size is a numeric bias-ply designation in which the 520 represents the tire's nominal section width class and the 13 identifies the rim diameter. For the 1966 Austin A 40, this is the traditional bias-ply fitment and it is the natural starting point for owners who want a more vintage tire presentation. Choices in this size include blackwall, narrow whitewall, and wide whitewall treatments from Firestone and Premium Sport across Firestone Classic Bias Ply and Premium Sport Lowrider lines. It deserves close attention when period-style stance and sidewall appearance matter as much as basic size.
Fitment is straightforward here because the covered 1966 Austin A 40 sub-model uses the same two 13-inch tire size paths. The important decision is less about trim variation and more about whether the car is being kept on bias-ply tires or set up for radial fitment.
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1966 Austin A 40 (opt. rim)
The 1966 Austin A 40 (opt. rim) can use either the 145R13 radial size or the 520-13 bias-ply size. That makes tire selection more about construction choice, sidewall appearance, and wheel compatibility than about separating one trim-specific size from another.
Bias-Ply to Radial Tire Conversion for the 1966 Austin A 40
For the 520-13 bias-ply size, three radial-equivalent options are available. 155R13 is the 80-series metric radial equivalent, P155/75R13 is the 75-series P-metric radial alternative, and P155/70R13 is the 70-series P-metric radial alternative. These choices move from a traditional Euro-metric radial format to lower-profile P-metric options. A recommended rim-width range of 4 to 5 inches applies, and wheel diameter, wheel width, and vehicle clearance should all be checked before making the switch.
Modern Radial Equivalents
155R13
Equivalent 80-series Metric Radial (520-13)
P155/75R13
Equivalent P-metric 75-series Radial (520-13)
P155/70R13
Equivalent P-metric 70-series Radial (520-13)
Important Considerations When Replacing Bias Ply With Radial
Compare overall diameter and section width carefully to ensure proper fit.
Verify recommended rim range (4-5 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 1966 Austin A 40 Tires for Sale
Available 1966 Austin A 40 tire choices span 145R13 radial and 520-13 bias-ply fitments from Michelin, Firestone, and Premium Sport. The product grid lets you compare blackwall, narrow whitewall, and wide whitewall styles, along with classic bias-ply and metric radial tire series.
These 1966 Austin A 40 tire FAQs focus on the two 13-inch fitments, radial versus bias-ply selection, available sidewall styles, radial equivalents for 520-13, and the checks that matter before putting a vintage small car back on the road.
Tire Size & Fitment
What tire size fits a 1966 Austin A 40?
A 1966 Austin A 40 uses two primary tire sizes: 145R13 in radial construction and 520-13 in bias-ply construction. Both sizes are built for 13-inch rims, but they represent different sizing systems and different approaches to how the car is set up.
That means the real fitment question is not just rim diameter, but whether the car is staying with a traditional bias-ply arrangement or using a radial setup. Checking the current wheel width, the tire already on the car, and the intended driving and appearance goals will help narrow the choice between the two primary fitments.
What size rim does a 1966 Austin A 40 use?
The 1966 Austin A 40 uses a 13-inch rim with both of its primary tire sizes. The radial 145R13 and the bias-ply 520-13 are both matched to that same rim diameter, so wheel diameter remains consistent even though tire construction and sizing format change.
Rim diameter is only one part of the fitment picture on a vintage car. Before changing from one construction type to another, it is smart to confirm actual wheel width as well, since some radial-equivalent options and several product choices are intended for specific width ranges rather than any 13-inch wheel.
What does 520-13 mean on a 1966 Austin A 40?
On a 1966 Austin A 40, 520-13 is a numeric bias-ply tire size. The 520 portion refers to the tire's nominal section-width class, and the 13 identifies the rim diameter in inches.
That older sizing format matters because it points you toward a traditional bias-ply tire rather than a modern metric radial. If the goal is to keep a vintage look, 520-13 is the fitment to study first, especially since it is available in blackwall, narrow whitewall, and wide whitewall versions with different visual character.
Bias-Ply & Radial Options
Is 520-13 a bias-ply or radial tire for the 1966 Austin A 40?
For the 1966 Austin A 40, 520-13 is a bias-ply tire size. It uses the older numeric bias-ply sizing system rather than a metric radial format, and it represents the more traditional vintage fitment path for this car.
That distinction affects both appearance and selection. A 520-13 bias-ply tire opens up period-style sidewall choices such as blackwall, narrow whitewall, and wide whitewall, while a move away from that construction calls for a separate fitment check around wheel width, radial sizing, and the overall setup of the car.
What radial tire sizes are equivalent to 520-13?
Radial equivalents for 520-13 include 155R13 as an 80-series metric radial, P155/75R13 as a 75-series P-metric radial, and P155/70R13 as a 70-series P-metric radial. These are equivalent-size alternatives to the original bias-ply format, not additional primary factory-style size designations.
Each of those options keeps the 13-inch rim diameter but uses a different radial sizing convention and profile family. A recommended rim-width range of 4 to 5 inches applies to the equivalent comparison, and the final choice should still be checked against the car's wheel width, physical clearance, and intended use.
What should I check before converting my 1966 Austin A 40 from bias-ply to radial tires?
Start by confirming the wheel diameter and wheel width on the car, then compare the intended radial equivalent against the existing setup. For a 520-13 Austin A 40, radial-equivalent options include 155R13, P155/75R13, and P155/70R13, with a recommended rim-width range of 4 to 5 inches.
A radial conversion also deserves a close look at steering clearance, fender clearance, suspension condition, and the way the car is actually driven. On an older car that may have changed wheels or ride height over the years, measuring the real setup is more useful than assuming any equivalent size will behave the same way.
Choosing the Right Tire
What should I consider when choosing a tire for a 1966 Austin A 40?
The first choice is between the two primary fitments: 145R13 radial or 520-13 bias-ply. From there, compare the tire's construction, sidewall appearance, brand, tire series, and any wheel-width guidance that applies to the way the car is currently equipped.
A buyer restoring a more traditional look may focus on the 520-13 bias-ply options, while someone prioritizing a radial setup may gravitate toward 145R13. It also helps to compare practical details such as load figures where stated, tire weight where relevant, and whether the car's existing wheels support the intended tire correctly.
What sidewall styles are available for 1966 Austin A 40 tires?
Sidewall choices for the 1966 Austin A 40 include blackwall, narrow whitewall, and wide whitewall, depending on the tire size and product line. Blackwall appears in both the 145R13 radial and 520-13 bias-ply selections, while the whitewall treatments appear within the 520-13 bias-ply offerings.
That gives the car noticeably different visual personalities without changing the basic 13-inch fitment family. A blackwall usually supports a cleaner, more understated presentation, while narrow and wide whitewalls push the car toward a stronger vintage style, so sidewall choice should match the overall restoration or driving theme.
What brands offer tires for the 1966 Austin A 40?
Tires for the 1966 Austin A 40 are available from Michelin, Firestone, and Premium Sport. Michelin and Firestone cover the 145R13 radial fitment, while Firestone and Premium Sport appear in the 520-13 bias-ply offerings with several appearance variations.
Brand alone should not be the only deciding factor on a vintage application like this. It is more useful to compare the correct size first, then look at whether the tire is radial or bias-ply, which series it belongs to, what sidewall style it uses, and whether the wheel dimensions on the car support that particular choice.
Restoration & Appearance
Which tire should I choose for a period-style 1966 Austin A 40?
For a period-style 1966 Austin A 40, the 520-13 bias-ply fitment is the natural place to start. It uses a traditional numeric bias-ply size and is available in several visual treatments, including blackwall, narrow whitewall, and wide whitewall, which can shape the car's overall presentation.
The right look depends on how authentic or personalized the restoration is meant to be. If exact originality matters, compare the intended tire against marque references, period photography, or model-specific restoration guidance, then choose the sidewall treatment that best matches the car's era and the style you want to preserve.
Does correct tire fitment matter for a 1966 Austin A 40 restoration?
Correct tire fitment matters on a 1966 Austin A 40 because tire construction, size format, and sidewall style all influence how the car sits and how authentic it looks. The difference between a 520-13 bias-ply tire and a 145R13 radial is not just technical; it also changes the visual character of the car.
Restoration-minded owners usually get better results by choosing tires that match the intended theme of the build before looking at brand or cosmetic details. Confirming the wheel setup first also helps prevent a mismatch between the tire's appearance and the way the car actually needs to be driven or displayed.
Fitment, Maintenance & Road Use
Can modifications affect tire fitment on a 1966 Austin A 40?
Yes, modifications can affect tire fitment on a 1966 Austin A 40 even when the car still uses a 13-inch wheel. Changes such as aftermarket wheels, altered wheel width, suspension work, ride-height changes, or body adjustments can all influence which tire size and construction work comfortably on the car.
That matters most when moving between the 520-13 bias-ply and 145R13 radial fitments or when considering a radial equivalent for 520-13. Measuring the actual wheel and checking steering and fender clearance on the car as it sits now is the safest way to avoid selecting a tire on assumption alone.
What should I inspect before driving a 1966 Austin A 40 on new tires?
Before driving a 1966 Austin A 40 on new tires, inspect the wheels for correct diameter and sound condition, then verify proper tire pressure, secure mounting, and adequate clearance at the fenders and steering components. It is also smart to check the suspension and steering system for looseness that could affect how the car tracks.
A vintage car that has spent long periods parked deserves extra attention after tire installation. Look over the old valve hardware, watch for uneven stance, and recheck clearance after a short drive, especially if the car has changed from bias-ply to radial construction or is using wheels that are no longer original in width.
How should tires on a collector 1966 Austin A 40 be maintained?
Tires on a collector 1966 Austin A 40 should be kept at the correct operating pressure for the tire being used and inspected regularly for cracking, bulges, cuts, uneven wear, and gradual air loss. Because collector cars are often driven less, age and storage condition matter almost as much as tread depth.
Good maintenance also includes storing the car away from prolonged sunlight, moisture, and ozone sources, and moving it periodically so one spot of the tire is not loaded for too long. A quick pre-drive inspection is worthwhile every time the car comes out after sitting, especially on older bias-ply tires or low-mileage vintage radials.
