1968 Morgan Plus 4 Tires

The 1968 Morgan Plus 4 uses four primary tire sizes across its covered fitments: 155R15, 560-15, 165R15, and 590-15. The Base sub-model uses 155R15 as its radial size and 560-15 as its bias-ply size, while the Plus sub-model uses 165R15 as its radial size and 590-15 as its bias-ply size.

That means the first step is identifying whether the car is a Base or a Plus, not simply choosing any 15-inch tire. After the sub-model is confirmed, the next question is whether the car is being kept in its bias-ply fitment or matched to its radial fitment, since size format, appearance, and product choices differ between those two paths.

All four primary tire sizes used on the 1968 Morgan Plus 4 are built for a 15-inch rim diameter. That includes the radial sizes 155R15 and 165R15 as well as the bias-ply sizes 560-15 and 590-15, so wheel diameter remains consistent even though the tire sizes and constructions vary by sub-model.

A shared 15-inch rim diameter does not mean every tire choice is automatically interchangeable. Wheel width, the car's actual sub-model, and whether the car has been fitted with non-original wheels should still be checked, especially when moving between narrow bias-ply tires and radial sizes that may have different recommended wheel-width ranges.

No. The 1968 Morgan Plus 4 Base and Plus sub-models use different primary tire sizes. The Base uses 155R15 in radial form or 560-15 in bias-ply form, while the Plus uses 165R15 in radial form or 590-15 in bias-ply form.

That difference matters because the correct tire decision begins with the exact sub-model, even though both versions use 15-inch wheels. A buyer looking at period-style bias-ply tires, radial alternatives, or whitewall versus blackwall options should make those appearance and construction choices only after confirming whether the car is a Base or a Plus.

560-15 is a bias-ply tire size for the 1968 Morgan Plus 4 Base. It is the vintage numeric bias-ply fitment associated with that sub-model, while 155R15 is the radial size tied to the same version of the car.

Choosing between those two formats affects more than the size code on the sidewall. A buyer comparing 560-15 with a radial alternative should confirm wheel width, overall tire dimensions, and clearance at the fenders and steering, since staying with bias-ply preserves the traditional format while moving to a radial changes the construction type and sizing convention.

Radial equivalents for 590-15 include 165R15 as an 80-series metric radial, P165/75R15 as a 75-series P-metric radial, and P175/70R15 as a 70-series P-metric radial. Those options give the 1968 Morgan Plus 4 Plus owner several ways to compare a traditional bias-ply size with modern radial sizing formats.

The practical difference is that the alternatives move from a classic Euro-metric radial convention to progressively more modern P-metric profile choices. Each one should be treated as an alternative to evaluate rather than an automatic swap, so wheel width, section fit, and available clearance around the Morgan's front and rear wheel openings should be checked before converting.

A bias-look radial equivalent is available for the 560-15 size used on the 1968 Morgan Plus 4 Base. That equivalent is 560R15, which keeps a more traditional visual presentation while using radial construction rather than a true bias-ply build.

This kind of option is useful for an owner who wants a vintage-style appearance without staying in the original bias-ply construction format. The wheel still needs to be appropriate for the conversion, and the vehicle should be checked for tire dimensions and clearance just as carefully as it would be with any other radial-equivalent change.

A 155R15 choice for a 1968 Morgan Plus 4 starts with confirming that the car is the Base sub-model using the radial fitment. After that, compare the available radial series, blackwall presentation, rim-width suitability, and product details such as load figures or speed-designated versions where they appear.

The available 155R15 range includes Firestone, Michelin, Avon, and Vredestein options, so the main decision is less about basic fitment and more about the kind of radial tire you want on the car. Buyers should still verify the wheel width on the vehicle and consider whether the goal is touring use, sporting road use, or a more restoration-oriented appearance.

Sidewall choices for the 1968 Morgan Plus 4 include blackwall, narrow whitewall, and wide whitewall, depending on the tire size. The radial sizes are mostly blackwall, although 165R15 also appears with narrow and wide whitewall treatments, while the bias-ply sizes include blackwall and whitewall options as well.

That variety matters because sidewall treatment changes the look of the car even when the size stays correct. A buyer trying to preserve a restrained British sports-car presentation may lean toward blackwall, while a more restoration-oriented or custom visual direction may call for one of the available whitewall treatments in the matching size and construction.

Brands available across the 1968 Morgan Plus 4 fitments include Firestone, Michelin, Avon, Vredestein, BFGoodrich, American Classic, Coker Classic, US Royal, and Pro-Trac. Brand availability depends on the size, with some choices appearing only in certain radial or bias-ply fitments.

That means the brand decision should come after the correct sub-model and tire size are confirmed. Once the size is narrowed down, compare the brands by construction type, sidewall treatment, tire series, and wheel-width compatibility rather than assuming that every brand offers the same style or the same type of fitment for this Morgan.

A period-style 1968 Morgan Plus 4 usually starts with the correct primary size for the exact sub-model and, in many cases, the corresponding bias-ply format. That means 560-15 for the Base or 590-15 for the Plus if the goal is to retain the traditional numeric sizing style associated with the car's vintage character.

From there, the appearance decision becomes more specific, including blackwall versus whitewall treatment and how closely the finished look matches the owner's restoration direction. Exact originality can vary by market and prior history, so owners pursuing a very precise restoration should compare their tire choice with authoritative Morgan references and marque-specific documentation.

Tire construction changes the restored appearance of a 1968 Morgan Plus 4 because the car was offered in both vintage bias-ply sizing and Euro-metric radial sizing. A numeric bias-ply size such as 560-15 or 590-15 gives the car a more traditional visual language, while 155R15 or 165R15 presents a more modern radial format.

Sidewall treatment builds on that difference, since blackwall, narrow whitewall, and wide whitewall options are not distributed evenly across every size. Owners balancing drivability with a vintage look may also consider a radial alternative or, for the Base bias-ply size, a bias-look radial, but the final choice should still suit the car's wheels and restoration goals.

Yes. A 1968 Morgan Plus 4 may have the correct nominal tire size on paper and still run into fitment problems if aftermarket wheels, altered wheel widths, suspension changes, or body modifications have been made over the years. This matters especially when moving between the original bias-ply sizes and radial alternatives.

The safest approach is to verify the actual wheel diameter and width on the car, then check steering travel and fender clearance with the suspension loaded. Cars that sit lower than stock or use different wheel offsets deserve extra attention, because even a correct-size tire can become a poor choice if the wheel and chassis setup have changed.

Before putting a 1968 Morgan Plus 4 back on the road with new tires, inspect the wheels for damage or corrosion, confirm that the tire size matches the car's exact sub-model fitment, and make sure the tires are seated and inflated properly. It is also wise to check for rubbing at full steering lock and through suspension movement.

A broader road-use check should include brake condition, steering play, suspension wear, and the general condition of the spare if one is carried. Classic cars that see limited mileage benefit from a cautious first drive, because noises, pulling, or contact marks can reveal wheel or clearance issues before they become a larger problem.

Tires on a collector-driven 1968 Morgan Plus 4 should be checked regularly for pressure loss, sidewall cracking, tread wear, cuts, bulges, and signs of age-related hardening. Low-mileage cars often spend long periods parked, so condition matters just as much as tread depth whether the car is running bias-ply tires or radials.

Storage habits also affect service life. Keeping the car away from prolonged sunlight, moisture, excess heat, and ozone sources helps protect the rubber, and moving the car periodically can help avoid long-term flat spotting. A brief visual inspection before each drive is a smart routine, particularly on a lightweight vintage sports car that may sit between outings.