The 1968 Austin 1800 came from an era when British family cars were being pushed toward smarter packaging, front-wheel-drive practicality, and more modern road manners. Known for its roomy interior and no-nonsense engineering, the Austin 1800 appeals today to owners who appreciate unusual but highly usable classics. Tire fitment for this model centers on two 13-inch choices: a 175R13 radial or a 650-13 bias-ply. That gives owners a meaningful decision between a more contemporary radial format and period-style bias-ply options, along with whitewall variations in the bias-ply size. The right choice depends on whether the goal is road use, traditional appearance, or a careful balance of both.
Which Tire Size Is Right for The 1968 Austin 1800
The 1968 Austin 1800 uses two primary tire sizes on the same 13-inch rim: 175R13 in radial construction and 650-13 in bias-ply construction. Because both sizes apply to the Base model, the main decision is not sub-model identification but whether to keep a period-style bias-ply setup or choose the radial size associated with more modern tire construction. Sidewall appearance also matters if a restoration-oriented look is part of the plan.
175R13 is a Euro-metric radial size in which 175 refers to nominal section width in millimeters, R identifies radial construction, and 13 is the wheel diameter in inches. On the 1968 Austin 1800, this size represents the radial-format fitment and suits owners who want to stay with the vehicle's radial sizing convention on a 13-inch rim. The format will be familiar to buyers comparing classic European tire sizes, even though it does not state an aspect ratio in the code. It is the size to evaluate when keeping the Austin in its radial fitment path is the priority.
650-13 is a numeric bias-ply size in which 650 represents an approximate 6.50-inch nominal section width and 13 identifies the rim diameter. For the 1968 Austin 1800, this is the bias-ply fitment and it carries the more traditional construction style many restoration-minded owners expect to see on a period car. Available choices include Coker Classic and US Royal offerings in both narrow whitewall and wide whitewall treatments. This size is worth considering when vintage appearance matters as much as fitment, provided the wheel and overall setup remain appropriate for bias-ply use.
Sub-model fitment is straightforward for the 1968 Austin 1800 because the covered Base model uses the same two 13-inch tire sizes. The important step is deciding between the radial and bias-ply fitment paths rather than sorting through different trim-specific sizes.
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1968 Austin 1800 Base
The 1968 Austin 1800 Base uses either 175R13 radial or 650-13 bias-ply tires on a 13-inch rim. That gives the owner a clear choice between maintaining a radial-format setup or selecting a more traditional bias-ply presentation with whitewall styling options.
Bias-Ply to Radial Tire Conversion for the 1968 Austin 1800
For the 1968 Austin 1800, the 650-13 bias-ply size has four radial-equivalent options. Those include 175R13 as the 80-series metric radial equivalent, P175/75R13 as the 75-series P-metric radial, P185/70R13 as the 70-series P-metric radial, and 650R13 as the bias-look radial equivalent. Together, these options span traditional metric radial sizing, later P-metric profiles, and a radial that keeps a more vintage visual character. A recommended rim width range of 4 to 6 inches is associated with these equivalents, and wheel width, overall dimensions, and clearance should still be checked before changing sizes or construction.
Modern Radial Equivalents
175R13
Equivalent 80-series Metric Radial (650-13)
P175/75R13
Equivalent P-metric 75-series Radial (650-13)
P185/70R13
Equivalent P-metric 70-series Radial (650-13)
650R13
Bias-look Radial Equivalent (650-13)
Important Considerations When Replacing Bias Ply With Radial
Compare overall diameter and section width carefully to ensure proper fit.
Verify recommended rim range (4-6 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 1968 Austin 1800 Tires for Sale
Available 650-13 choices focus on bias-ply construction from Coker Classic and US Royal, with Coker Classic Bias Ply and US Royal Classic Bias Ply series represented. The key buying differences are sidewall treatment and presentation, with both narrow whitewall and wide whitewall options built for 13-inch fitment.
These FAQs for the 1968 Austin 1800 cover the two primary tire sizes, 13-inch rim fitment, bias-ply versus radial choices, radial equivalents for 650-13, whitewall selection, and the checks worth making before road use on a collector-era Austin.
Tire Size & Fitment
What tire size fits a 1968 Austin 1800?
The 1968 Austin 1800 uses two primary tire sizes: 175R13 in radial construction and 650-13 in bias-ply construction. Both are 13-inch fitments, so the choice is tied more to tire type and intended presentation than to a different wheel diameter.
That means the first question is whether the car is staying with a radial-format setup or moving toward a period-style bias-ply look. On a car that has been modified over the years, it is still smart to confirm the actual wheel size and width before selecting either size.
What size rim does a 1968 Austin 1800 use?
Both primary tire sizes for the 1968 Austin 1800 are built around a 13-inch rim diameter. The radial 175R13 and the bias-ply 650-13 share that same basic wheel diameter, which simplifies the wheel-diameter side of the fitment decision.
Rim diameter is only part of the picture, especially if the car no longer has its original wheels. Wheel width should also be checked, particularly when comparing the 650-13 bias-ply fitment to radial-equivalent options, since construction changes can affect how a tire works with the wheel and the car's available clearance.
Does the 1968 Austin 1800 Base use the same tire size?
Yes. The 1968 Austin 1800 Base uses the same two fitment paths found on the model overall: 175R13 in radial construction and 650-13 in bias-ply construction. There is no separate Base-only tire size to sort out here.
That keeps the buying decision focused on construction and appearance rather than trim differences. A Base owner can concentrate on whether the car is being kept in a more traditional bias-ply style, shifted toward a radial alternative, or selected around the whitewall look that best suits the car.
Bias-Ply & Radial Options
Is 650-13 a bias-ply or radial tire for the 1968 Austin 1800?
650-13 is the bias-ply tire size used on the 1968 Austin 1800. It is a vintage numeric bias-ply format, with the 650 code indicating nominal section width and the 13 indicating the wheel diameter in inches.
That matters because a buyer looking at 650-13 is usually choosing a more traditional construction style and appearance. It is also the size tied to the available whitewall bias-ply products, so the decision often comes down to whether period-style presentation is more important than moving to a radial equivalent.
What radial tire sizes are equivalent to 650-13?
Radial equivalents for 650-13 include 175R13 as an 80-series metric radial, P175/75R13 as a 75-series P-metric radial, P185/70R13 as a 70-series P-metric radial, and 650R13 as a bias-look radial equivalent. These are alternatives tied specifically to the 650-13 bias-ply size.
Each option reflects a slightly different sizing convention and visual direction, so the choice is not just about keeping the same rim diameter. Wheel width, overall tire dimensions, and clearance around the suspension and body should all be checked before substituting any equivalent for the original bias-ply size.
Should I use bias-ply or radial tires on a 1968 Austin 1800?
Either can be appropriate on a 1968 Austin 1800, depending on what you want from the car. The primary bias-ply fitment is 650-13, while 175R13 represents the radial fitment and additional radial equivalents exist for owners comparing alternatives from the 650-13 size.
A bias-ply choice usually aligns better with a traditional vintage presentation, especially with whitewall options available in 650-13. A radial path may better suit owners prioritizing a radial-format setup, but the switch should still be checked against wheel width, clearance, and the current condition of the car's suspension and steering components.
Choosing the Right Tire
What should I consider when choosing a 650-13 tire for a 1968 Austin 1800?
Start with the role the car will play. A 650-13 tire on a 1968 Austin 1800 is the bias-ply fitment, so the main considerations are whether a traditional construction matches the car's intended look, whether the 13-inch wheel setup is correct, and which sidewall treatment suits the car.
Available 650-13 choices also differ by brand, tire series, rim-width specification, load capacity, and sidewall style. Looking at those details helps narrow the selection between a more understated narrow whitewall and a more pronounced wide whitewall without drifting away from the proper size family.
What sidewall styles are available for 1968 Austin 1800 tires?
The available 650-13 tires for the 1968 Austin 1800 include narrow whitewall and wide whitewall sidewall styles. Those choices are tied to the bias-ply product selection, giving the car two distinctly different vintage visual treatments within the same basic size.
That makes sidewall style an appearance decision as much as a fitment one. A narrow whitewall tends to keep the presentation subtler, while a wide whitewall creates a stronger period-style statement, so the right choice depends on how original-looking, understated, or visually prominent the finished car is meant to appear.
What brands offer tires for the 1968 Austin 1800?
Coker Classic and US Royal both offer 650-13 tires for the 1968 Austin 1800. Their products appear in bias-ply construction and are available within Coker Classic Bias Ply and US Royal Classic Bias Ply series, with whitewall options in each brand's lineup.
Brand choice should be considered alongside the actual tire details rather than on name alone. Comparing sidewall style, tire series, rim-width range, and load specification will usually be more useful than trying to treat one brand as universally better for every Austin 1800 owner or every restoration goal.
Restoration & Appearance
Which tire should I choose for a period-style 1968 Austin 1800?
For a period-style 1968 Austin 1800, the 650-13 bias-ply size is the natural starting point because it carries the vintage numeric format and traditional construction many owners associate with an earlier visual presentation. Available whitewall versions also make it easier to shape the car's final look.
The exact appearance choice still depends on how the car is being restored and how closely originality matters to the owner. If the goal is strict historical accuracy, marque literature, period photos, and Austin-specific club references are worth checking before settling on a particular whitewall treatment or construction style.
How does tire construction affect the appearance of a restored 1968 Austin 1800?
Tire construction changes more than the spec sheet on a restored 1968 Austin 1800. A 650-13 bias-ply gives the car a more traditional vintage character, while a radial-format tire such as 175R13 or a radial equivalent usually creates a more modern visual impression even when the size remains close.
That visual difference is why many restorers decide on construction early in the project rather than treating it as a final detail. Sidewall style also plays a major role, especially when choosing between narrow and wide whitewall bias-ply options that can make the same Austin look restrained or more distinctly period-styled.
Fitment, Maintenance & Road Use
Can modifications affect tire fitment on a 1968 Austin 1800?
Yes. A 1968 Austin 1800 may originally center on 13-inch fitment, but aftermarket wheels, changes in wheel width, suspension work, or body alterations can all affect how a 175R13, 650-13, or radial equivalent sits on the car. Even small changes can alter clearance.
That is especially important when evaluating a switch from bias-ply to radial sizing. A car that has been lowered, fitted with different wheels, or rebuilt with non-stock components should have wheel dimensions and clearance checked at the fenders and steering range before any tire is chosen strictly by catalog size.
What should I inspect before driving a 1968 Austin 1800 on new tires?
Before driving a 1968 Austin 1800 on new tires, inspect the wheels for correct diameter and condition, confirm proper inflation, and look over the suspension and steering for looseness or wear that could affect how the car tracks. A basic clearance check is also worthwhile once the tires are mounted.
Collector cars often sit for long periods, so it also helps to inspect the rest of the tire-related system rather than focusing only on the new rubber. Valve stems, wheel fasteners, alignment condition, and any signs of rubbing on the inner fender or suspension should be addressed before regular road use.
How should tires on a collector 1968 Austin 1800 be maintained?
Tires on a collector 1968 Austin 1800 should be checked regularly for pressure loss, tread wear, sidewall cracking, cuts, bulges, and age-related deterioration. Cars that are driven infrequently can develop condition issues simply from long storage, even when tread depth still looks acceptable.
Good storage habits matter just as much as routine inspection. Keeping the Austin away from prolonged sunlight, excess heat, moisture, and ozone sources helps preserve tire condition, and a quick visual inspection before every drive is smart when the car is used seasonally or only on occasional weekend outings.
