1966 Morgan Tire Fitment Guide

1966 Morgan vehicles use four tire sizes overall: 155R15, 560-15, 165R15, and 590-15. The 4-4 Series uses 155R15 and 560-15, while the Plus 4 uses those same two sizes plus 165R15 and 590-15. All four sizes fit 15-inch rims, but the rim-width requirements are not identical. 155R15 works with 4.00 to 5.50-inch rims, 560-15 uses 4.5 or 4.50 to 5.50-inch rims depending on the tire, 165R15 uses 4.50 to 6.00-inch rims, and 590-15 uses 4.00 to 4.50-inch rims where that range is specified.

That means year and make alone are not enough if you own a 1966 Morgan Plus 4, because the Plus 4 spans both shared and model-specific sizes. Start by identifying the model, then confirm which tire size matches the wheel currently on the car and the look or driving character you want. If your Morgan already has reproduction wheels or has been changed from its earlier fitment, verify the wheel width before settling on a tire size.

On a 1966 Morgan, 155R15 is a metric radial size. The 155 refers to a nominal section width of 155 millimeters, the R indicates radial construction, and the 15 is the rim diameter in inches. In this older metric style, no aspect ratio is printed, and the size is conventionally treated as an 80-series radial. That makes 155R15 a very familiar postwar European sports-car format rather than an American numeric bias-ply code.

For a Morgan owner, the practical significance is that 155R15 points you toward a radial tire family with a more modern construction style than 560-15 or 590-15. It is shared by both the 4-4 Series and Plus 4, so it can be a useful starting point if you are still confirming your exact car. You should still check whether you want tube-type or tubeless radial versions, since both appear within this size.

No, not every 1966 Morgan model uses the same full size range. The 4-4 Series and Plus 4 both use 155R15 and 560-15, but only the Plus 4 also uses 165R15 and 590-15. All of those sizes mount on 15-inch rims, so rim diameter is consistent across the year even though the full fitment range is not. The difference is in the size options tied to the model, not in a change from one wheel diameter to another.

That makes model identification especially important if you are working with a Plus 4, because it opens the door to larger radial and bias-ply choices not shared with the 4-4 Series. If you own a 4-4 Series, your path is simpler because both of its sizes are also the common sizes across the Morgan range. A quick check of the car’s actual installed tire size and wheel width will usually settle the question before you choose a replacement.

For a 1966 Morgan, 155R15 and 560-15 are the two shared sizes across both the 4-4 Series and Plus 4, but they represent different construction philosophies. 155R15 is a radial size offered in blackwall form, while 560-15 is a bias-ply size offered with narrow whitewall and wide whitewall treatments. The radial choice generally aligns with owners who want a more modern road-going tire character, while the bias-ply choice aligns with owners pursuing a more traditional mid-century appearance and feel.

The best choice depends less on whether the tire will physically mount, since both fit 15-inch rims, and more on how you use the car. If your Morgan is judged for originality or you want the visual language of a period British sports car interpreted through classic whitewall options, 560-15 has a stronger vintage presentation. If you plan to drive the car regularly on modern roads and want a radial-format option, 155R15 is the more natural place to start.

1966 Morgan tires come in a wider range of sidewall treatments than many buyers expect. The 155R15 radial choices are blackwall only. The 560-15 bias-ply options are available with narrow whitewall and wide whitewall styling. The Plus 4-specific 165R15 radial expands the range further with blackwall, narrow whitewall, and wide whitewall choices, while 590-15 comes in blackwall and wide whitewall form.

For most British sports-car restorations, blackwall is often the most natural visual direction, especially if you want a leaner, competition-oriented appearance. Whitewall choices can still suit certain presentation goals, personal taste, or period custom touches, particularly on a car restored to a specific regional style. Sidewall style changes the car’s stance and personality more than many owners expect, so it is worth deciding that visual direction before narrowing down brand and construction.

Several well-known brands cover 1966 Morgan sizes. 155R15 is available from Firestone and Michelin. 560-15 is available from Firestone and US Royal. 165R15 is available from Coker Classic, American Classic, Firestone, and BFGoodrich. 590-15 is available from BFGoodrich and Avon. That gives the Morgan range a mix of heritage American brands and established European-style offerings, especially in the radial sizes.

Brand choice usually matters most after you have already settled the size, construction, and sidewall style. Michelin and Avon tend to appeal to buyers looking for historically European-flavored options, while Firestone, BFGoodrich, US Royal, Coker Classic, and American Classic broaden the period-style and reproduction market. A sensible way to narrow the field is to start with the exact size your model uses, then choose the sidewall appearance you want before comparing individual tire series.

Rim-width requirements for 1966 Morgan tires depend on the size. 155R15 fits 4.00 to 5.50-inch rims. 560-15 appears on 4.5-inch rims in some versions and 4.50 to 5.50-inch rims in others. 165R15 fits 4.50 to 6.00-inch rims. 590-15 fits 4.00 to 4.50-inch rims where the fitment range is given. All of these tires share a 15-inch rim diameter, but width compatibility is more size-specific.

That matters because a Morgan may still have original wheels, replacement steel wheels, or later aftermarket wheels that keep the same diameter but change width. Before finalizing a tire, measure the wheel or confirm its width through the wheel manufacturer if it is not original. Matching the tire to the proper width range helps preserve the intended tread shape and sidewall profile instead of forcing a tire onto a wheel that is too narrow or too wide for it.

Inner-tube requirements on 1966 Morgan tires depend on the specific size and product. Within 155R15, tube status varies by product: Michelin X is marked TL, Michelin XAS is marked TT, and Michelin XAS-FF is marked TL. The other Morgan sizes shown here do not all carry tube markings in the same way, so the safest approach is to check the sidewall designation of the exact tire you are considering. Tube-type and tubeless versions can exist even within the same nominal size family.

That distinction matters because many vintage wheel designs and restoration practices still use tubes even when a nominally similar tire may also exist in tubeless form. If your Morgan retains original-style wheels, confirm whether the wheel itself is appropriate for tubeless service instead of assuming the tire alone answers the question. Matching tire type, wheel construction, valve hardware, and installation method is more important than relying on size code alone.

Because all 1966 Morgan sizes in this range use a 15-inch rim diameter, original Morgan wheels can often be candidates for more than one tire size. That is true for the shared 155R15 and 560-15 choices and also for the Plus 4-only 165R15 and 590-15 sizes. The limitation is wheel width, not wheel diameter. A tire that fits a 15-inch rim still has to fall within the wheel-width range appropriate to that specific size.

In practical terms, a 15-inch wheel that works well with 155R15 may not automatically be right for 165R15 or 590-15 without confirming width. That is especially relevant on a Plus 4, where the model spans both broader and narrower rim-width ranges depending on the tire chosen. If the wheels are original and you want to move from bias-ply to radial or from one Plus 4-specific size to another, verify width before treating them as interchangeable.

A 1966 Morgan should be stored in a cool, dry space away from direct sunlight, electric motors, battery chargers, welders, and other ozone-producing equipment that can age rubber. Keep the tires clean, maintain proper inflation, and avoid parking for very long periods on damp ground or oil-stained concrete. Bias-ply tires such as 560-15 and 590-15 are more prone to temporary flat-spotting during long static storage, while older-style sidewalls of any construction can suffer from neglect if the car sits for extended periods.

If the Morgan will be parked for months, moving it periodically or supporting it in a way that reduces constant loading can help preserve tire shape. A breathable cover and a stable indoor temperature are more valuable than heavy cosmetic dressings or tire shine products. Storage habits matter just as much as miles on a collector car, especially with a light sports car that may spend more time parked than driven.

Tires on a 1966 Morgan should be judged more by age and condition than by mileage. Collector cars often accumulate very few miles, yet rubber still hardens and ages with time. A practical rule is to evaluate the tires carefully once they reach about five to seven years old and to treat around ten years as a point where replacement deserves serious consideration, even if tread depth still appears healthy. The DOT date code on the tire is the usual reference for age.

That approach is especially important on a Morgan because the car’s low weight can hide aging tires that still look usable at a glance. Sidewall cracking, a hardened tread surface, persistent vibration, or loss of pressure are better warning signs than mileage alone. If the car has sat unused for long periods, age-related inspection matters even more than odometer readings when deciding whether the tires should stay in service.

Tires on a 1966 Morgan should be inspected before every drive, with a more thorough check before any longer outing. Look for visible cracking, cuts, bulges, irregular tread wear, and signs that the tire has been run underinflated. Pressure should be checked cold, and any tire that has begun losing air more quickly than usual deserves closer attention. If your setup uses tube-type tires or tubes inside vintage-style fitments, the valve stems and sealing condition deserve inspection as well.

That pre-drive habit is particularly valuable on lightly used sports cars, because time between drives can allow problems to go unnoticed. A short trip around town and a full day’s drive place very different demands on an older car and its tires. Building tire inspection into the same routine as checking fluids, lights, and fasteners is one of the simplest ways to keep a 1966 Morgan ready for reliable use.

For a 1966 Morgan 4-4 Series, bias-ply construction would have been the historically expected original-type tire format in period, even as radial adoption was becoming more common in European cars during the decade. The shared Morgan fitments here are 560-15 in bias-ply form and 155R15 in radial form, both on 15-inch rims. That means a restorer usually treats 560-15 as the more conventionally original-style direction, while 155R15 reflects the era’s transition toward radial construction rather than an obviously modern oversized change.

Exact factory fitment can still vary by market, delivery region, and how a specific car was equipped when new, so event-level authenticity should be checked against period manuals, photographs, and Morgan club resources. For most restoration work, getting the size family, construction type, and sidewall presentation right matters more than chasing an unsupported original brand claim. Start with the model, then verify whether your restoration goal is factory-correct, period-accessorized, or simply visually sympathetic.

Correct tire fitment matters a great deal when a 1966 Morgan is judged for authenticity. Size, construction type, and sidewall appearance all affect whether the car reads as properly restored for its era. A radial tire on a car being judged to strict factory-original standards may be questioned if the expected presentation is bias-ply, and an eye-catching whitewall can look out of place if the restoration target calls for a more understated British sports-car appearance.

The right answer depends on the kind of event and the standard being applied. A local show may reward presentation and overall finish, while marque judging is usually much more sensitive to details such as tire profile, sidewall treatment, and construction type. If showing is part of your plan, choose the tire after deciding which standard you are restoring toward, and use club guidance to confirm what that standard actually expects.

For a 1966 Morgan in 155R15, Michelin X and Michelin XAS differ in both service type and speed marking. Michelin X appears as 155R15 82T TL, making it a tubeless radial with a T speed rating and a 118 mph ceiling. Michelin XAS appears as 155HR15 82H TT, making it a tube-type radial with an H speed rating and a 130 mph ceiling. Both fit 15-inch rims, and the XAS also carries a 4.00 to 5.50-inch rim-width range.

That means the decision is not just about brand or tread heritage, but also about how the tire will be installed and what service character you want from the car. A buyer keeping original-style wheels may prefer to think carefully about tube compatibility before choosing between them. If your Morgan is driven regularly at sustained road speeds, the speed-category difference is also worth noting even when the car itself is seldom pushed anywhere near those limits.

1966 Morgan tires can be appropriate for highway driving when they are the correct size, properly installed, in sound condition, and used within their construction and speed limits. Among the radial options, Michelin X carries a T rating with a 118 mph ceiling, while Michelin XAS and XAS-FF carry H ratings with a 130 mph ceiling. The 590H15 Avon Turbospeed also carries an H rating with a 130 mph ceiling. Bias-ply and radial tires both remain viable on a vintage Morgan, but they deliver different road manners and should be chosen with the car’s intended use in mind.

On a mid-1960s Morgan, tire speed capability is only one part of the picture. Brake condition, steering precision, suspension health, wheel integrity, and alignment often matter just as much on real roads as the speed symbol on the sidewall. A well-sorted car on fresh, correctly fitted tires is far safer than one on old rubber chosen only for looks, so condition and setup deserve as much attention as the size code itself.

Inflation pressure for 1966 Morgan tires should not be guessed across different sizes. The tires themselves show distinct load-and-pressure figures: 155R15 appears with 1045 pounds at 44 psi in one version, 560-15 with 970 pounds at 32 psi, 165R15 with 1168 pounds at 35 psi or 1170 pounds at 36 psi depending on the tire, and 590-15 with 1050 pounds at 32 psi or 1,018 pounds on the Avon version. Those figures describe tire capacity at stated pressures, not automatically the ideal vehicle operating pressure.

For actual service use, begin with the pressure guidance appropriate to the car and then make sure the tire you selected supports that use within its rated range. Reproduction and specialty tires can differ from period originals, so the owner’s manual and the tire manufacturer’s service recommendations should be read together rather than treating one tire’s pressure figure as universal. Never transfer a pressure number from a 560-15 or 165R15 directly onto another Morgan size.

Before a longer drive in a 1966 Morgan, inspect all four tires and the spare for cracking, cuts, bulges, uneven wear, and proper cold inflation. Confirm that the valve stems are sound, and if your tire setup uses tubes, make sure there are no signs of slow leakage or disturbed hardware. A quick wheel-nut check, a look at tread depth, and a glance for any sidewall damage from previous curb contact are sensible steps before the car leaves the garage.

That tire check should be part of a broader pre-drive routine on a vintage sports car. Brakes, fluid levels, steering response, lights, and the general condition of the suspension all deserve attention before a long outing. Morgan owners often focus on what is visible, but the most useful habit is consistency: the same careful inspection before every meaningful drive will catch far more problems than a last-minute walkaround done only before major trips.