1966 Amphicar Tire Fitment Guide

1966 Amphicar vehicles use two tire sizes: 640-13 and 650-13. Both are bias-ply sizes for 13-inch wheels, and both apply to the Amphicar model. The 640-13 fits 4.00- to 4.50-inch rim widths, while the 650-13 fits 4.50- to 5.00-inch rim widths, so wheel width is part of the fitment decision even though both sizes share the same rim diameter.

That overlap at 4.50 inches is useful, but it does not mean every 13-inch wheel should automatically use either size. Owners should confirm the actual wheel width on the car, then compare the installed size with the desired restoration look. If your Amphicar already has an established wheel and tire combination that clears properly, use that as a baseline before changing to the other size.

On a 1966 Amphicar, 640-13 is a numeric bias-ply tire size. The 6.40 portion refers to the nominal section width in inches, and the 13 refers to the wheel diameter in inches. The dash-format size is typical of mid-century American and European bias-ply fitments, and in this case it mounts on a 13-inch wheel with an approved rim-width range of 4.00 to 4.50 inches.

For a buyer, that means 640-13 is not just a style label or brand code; it is the actual fitment language you should match to the car and wheel. On the 1966 Amphicar, this size is also tied to a wide whitewall presentation and an S-rated product option. If your priority is keeping a compact, period-style bias-ply look, 640-13 is the size to evaluate first.

On a 1966 Amphicar, 650-13 is also a numeric bias-ply tire size. The 6.50 portion indicates a nominal section width of 6.50 inches, and the 13 indicates a 13-inch wheel diameter. This size fits wider wheels than 640-13, with an approved rim-width range of 4.50 to 5.00 inches, which makes wheel measurement important before switching sizes.

The practical appeal of 650-13 is that it gives Amphicar owners more whitewall choices, including both wide and narrow whitewall versions from more than one brand. That can matter if your car is being restored to a particular visual theme or if you want a whitewall width that better suits the car's stance and trim. It still remains a bias-ply fitment, so the driving character stays in the traditional vintage category.

For a 1966 Amphicar, the choice between 640-13 and 650-13 starts with wheel width and the look you want, since both are 13-inch bias-ply tires. The 640-13 fits 4.00- to 4.50-inch rims and is available as a wide whitewall BFGoodrich option. The 650-13 fits 4.50- to 5.00-inch rims and comes in both wide and narrow whitewall styles from Coker Classic and US Royal.

If your goal is preserving a compact, traditional visual balance, 640-13 may be the more natural starting point. If your Amphicar is already on a wider 13-inch wheel or you want more flexibility in whitewall appearance, 650-13 opens up more choices. Since both sizes are bias-ply, this is less a bias-versus-radial decision and more a matter of matching the tire to the wheel and the car's finished presentation.

1966 Amphicar tires are available with both wide whitewall and narrow whitewall sidewall styles, depending on size. The 640-13 is offered as a wide whitewall, while the 650-13 is available in both wide whitewall and narrow whitewall forms. That gives the Amphicar owner a useful range of period-style visual options within the correct general era of bias-ply construction.

Wide whitewalls usually create the more formal mid-century look, while narrow whitewalls can feel slightly later and cleaner in appearance. On a novelty collector car like the Amphicar, sidewall style has a noticeable effect on the finished personality of the vehicle. If show authenticity matters, compare your choice against period photos, surviving original cars, and marque-club guidance before settling on a whitewall width.

Three brands cover 1966 Amphicar fitments: BFGoodrich, Coker Classic, and US Royal. BFGoodrich appears in the 640-13 size, while Coker Classic and US Royal both appear in the 650-13 size. All of these options are bias-ply tires, which keeps the available choices in line with the vintage construction style expected for a mid-1960s collector car.

Brand choice on a 1966 Amphicar is partly about appearance and partly about which size you need. If your car requires 640-13, the choice is straightforward, but 650-13 gives you room to compare whitewall width and brand presentation. Since Amphicars often attract owners who care about the car's distinctive personality as much as its mechanical function, the branding and sidewall look can matter almost as much as the size itself.

1966 Amphicar tires use 13-inch rims, but the approved wheel-width range depends on tire size. The 640-13 fits rims from 4.00 to 4.50 inches wide, while the 650-13 fits rims from 4.50 to 5.00 inches wide. That means the two sizes overlap at 4.50 inches, but otherwise each has its own wheel-width window that should be respected.

This is one of the most important setup checks before replacing tires on an Amphicar. A wheel that is too narrow or too wide for the chosen tire can affect the tire's shape, footprint, and overall appearance. Measure the wheel rather than guessing from memory, especially on a specialty car that may have changed hands several times or may have had wheels swapped during restoration.

Tube requirements for 1966 Amphicar tires should be confirmed by the specific tire marking and the wheel being used. The available size information here does not show a uniform tube-type or tubeless designation across every Amphicar tire option, so it is wise to verify the sidewall marking on the exact tire you choose and inspect the wheel's condition and design before final assembly.

That matters even more on an older specialty vehicle, because original wheels, restored wheels, and replacement wheels may not all be prepared the same way. Tube decisions should never be made by size alone. If your wheel condition, valve-stem arrangement, or tire marking raises questions, treat the tire manufacturer and a knowledgeable vintage tire installer as the final authority before mounting.

Original-style 1966 Amphicar wheels can potentially be used with both 640-13 and 650-13 because both sizes mount on 13-inch rims. The key limitation is wheel width: 640-13 fits 4.00 to 4.50 inches, while 650-13 fits 4.50 to 5.00 inches. A 4.50-inch wheel sits in the overlap zone, but narrower or wider wheels naturally narrow the choice.

That makes wheel measurement more important than assumption. If your Amphicar still has its original wheels, measure them and inspect them for age, corrosion, and previous repairs before deciding to switch sizes. A size change that looks minor on paper can still create a mismatch if the wheel falls outside the approved range, and that is especially worth checking on a specialty collector vehicle.

A 1966 Amphicar should be stored in a cool, dry, dark space away from direct sunlight, electric motors, battery chargers, welders, and other ozone-producing equipment that can age rubber. Bias-ply tires are especially prone to temporary flat-spotting after long static periods, so proper inflation and occasional movement help. Clean, dry floors and protection from standing moisture are also important for a vehicle that already lives in a moisture-conscious collector environment.

If the Amphicar will sit for months, move it periodically or support it in a way that reduces prolonged stress on one contact patch. Owners who keep the car for seasonal use should also check inflation before and after storage rather than assuming the tires held steady. A little attention during storage goes a long way toward preserving ride quality, sidewall appearance, and long-term service life.

On a 1966 Amphicar, tire life should be judged more by age and condition than by mileage. Collector vehicles often accumulate very few miles, yet the rubber still hardens and ages over time. A good rule is to begin careful evaluation around five to seven years of age and to give serious replacement consideration as tires approach ten years, using the date code and the tire's physical condition as your guide.

That approach is especially important for an Amphicar because a low-mileage, garage-kept car can still wear old tires that look better than they really are. Sidewall cracking, stiffness, vibration, and visible aging matter more than tread depth alone on a collector car. When in doubt, age out the tire before you trust it for touring, event driving, or any trip where roadside trouble would be especially inconvenient.

Tires on a 1966 Amphicar should be inspected before every drive and again before any longer outing. Look for sidewall cracking, cuts, bulges, irregular tread wear, air loss, and signs that the car has been sitting on low pressure. Since many collector cars spend more time parked than driven, problems often appear during storage rather than on the road.

A longer pre-drive check should also include valve stems, the spare, and wheel condition. If your Amphicar uses a tube-type setup, tube and stem condition become part of the inspection routine as well. Regular inspection is one of the easiest ways to catch age-related issues early, and it is far more practical than waiting for a problem to show up on a car that may only be driven occasionally.

A 1966 Amphicar Amphicar would have originally been associated with bias-ply tire construction, which was still standard for a specialty car of this period. The two fitment sizes tied to the model are 640-13 and 650-13, both on 13-inch wheels. No single original-equipment brand should be assumed without car-specific history, but the construction type and general sizing format are consistent with what buyers expect on a mid-1960s Amphicar.

For restoration work, the safest approach is to treat bias-ply construction and the correct size family as the baseline, then verify the exact size against surviving originals, period photos, and marque-club knowledge. Amphicars are unusual enough that individual cars may have long ownership histories and changes over time. If a concours standard matters, confirm the expected sidewall style and exact size before finalizing the restoration.

Correct tire fitment does matter when showing a 1966 Amphicar, especially because unusual collector vehicles tend to attract close attention from judges and knowledgeable enthusiasts. Size, construction type, and sidewall style all affect whether the car presents as authentically period-correct. A mismatch such as an incorrect size family or a sidewall treatment that does not suit the era can stand out quickly on a compact convertible with a lot of visible tire.

That does not mean every event uses the same judging standard, but it does mean tires should be chosen as part of the restoration, not as an afterthought. Compare your intended tire against period imagery and event rules, then ask an Amphicar specialist or marque club what is expected for the level of judging you care about. The more unusual the vehicle, the more visible those small details become.

On the 1966 Amphicar, the practical difference between wide whitewall and narrow whitewall tires is visual presentation rather than a change in tire construction, since the available options remain bias-ply. The 640-13 is offered as a wide whitewall, while the 650-13 gives you both wide whitewall and narrow whitewall choices. That means the whitewall decision is tied partly to the size you need and partly to the look you want the car to carry.

Wide whitewalls usually emphasize a fuller, more formal mid-century appearance, while narrow whitewalls create a subtler period look. Because the Amphicar is such a character-rich vehicle, that sidewall decision can noticeably influence how finished and authentic the car appears. Owners pursuing a show-field restoration should compare those choices against original photography and accepted Amphicar presentation standards before making the final call.

1966 Amphicar tires can be suitable for highway use when they are the correct size, properly mounted, correctly inflated, and in sound age-related condition. The available 640-13 option includes an S speed rating, which carries a 112 mph ceiling, while the 650-13 choices should be judged by the exact tire marking on the product selected. In real use, a vehicle of this era is usually limited more by its vintage chassis, braking, and overall mechanical character than by headline tire speed capability.

Highway safety on an Amphicar comes down to realistic use rather than theoretical maximums. A well-maintained car on fresh, properly chosen tires can be enjoyable on secondary roads and moderate touring, but age, balance, pressure, and road feel all matter on a vintage bias-ply setup. Before any sustained road trip, make sure the tires are age-appropriate, pressure-checked, and free from visible damage or long-storage deterioration.

Inflation pressure on a 1966 Amphicar should be set according to the car's factory recommendation and the exact tire you are using, not by transferring one number casually from another application. The available 640-13 carries a load figure of 1045 pounds at 32 psi, while the available 650-13 products carry 1150 pounds at 32 psi. Those figures show the tire's rated load-and-pressure relationship, but they are not a substitute for the vehicle maker's intended operating pressure.

The smart approach is to start with the owner's manual or factory literature for the car, then confirm that your chosen reproduction tire is being used within its rated range. Pressure affects handling feel, footprint, and wear, especially on a lightweight vintage vehicle with bias-ply construction. Keep all four tires checked with an accurate gauge and revisit pressures whenever the car has been sitting for an extended period.

Before taking a 1966 Amphicar on a longer drive, inspect each tire for cracking, cuts, bulges, embedded debris, uneven wear, and proper inflation. Check the valve stems, confirm the spare is usable, and make sure the wheels themselves are clean and sound. Since Amphicars are often used intermittently, storage-related aging can be just as important as miles driven.

Tires are only one part of the pre-drive routine on a specialty vehicle of this age. You should also confirm basic mechanical readiness such as steering feel, brakes, fluids, and overall roadworthiness before heading out. A careful inspection is especially worthwhile on an Amphicar because the car's novelty and collector value encourage occasional use, and occasional-use cars are the ones most likely to hide age-related issues.