1964 Amphicar Tires

The 1964 Amphicar uses two primary tire sizes: 640-13 and 650-13. Both are vintage numeric bias-ply sizes for 13-inch rims, and the Amphicar Base can be associated with either one rather than a single universal size across every car still on the road today.

That means the smartest first step is checking the tires and wheels currently on the vehicle before choosing a replacement. Because both sizes are close in type and rim diameter, it is easy to assume they are interchangeable, but wheel width, overall presentation, and clearance still deserve attention before selecting the next set.

The 1964 Amphicar uses a 13-inch rim diameter with both of its primary tire sizes, 640-13 and 650-13. The tire size code ends in 13, and the tire specifications for both sizes align with that same wheel diameter.

Rim diameter is only part of the fitment picture, so the wheel’s actual width should also be verified before choosing a tire. Product options in these sizes are associated with different rim-width ranges, and that becomes especially important if the car has replacement wheels or if a radial equivalent is being considered instead of a bias-ply tire.

On a 1964 Amphicar, 640-13 is a numeric bias-ply tire size. The 6.40 portion refers to the tire’s nominal section width in inches, while 13 identifies the wheel diameter. It is an older sizing system commonly seen on small and mid-century collector vehicles.

Understanding that format helps when comparing 640-13 with the alternate 650-13 size or with modern radial equivalents such as 175R13 and P175/75R13. The numbers do not translate one-for-one across sizing systems, so the better approach is to confirm wheel width, current tire size, and the kind of appearance or road use expected from the car.

For the 1964 Amphicar, 640-13 is a bias-ply tire size. It belongs to the vintage numeric bias-ply system and reflects the original-style construction family associated with this vehicle, rather than a modern radial format.

That distinction matters because a bias-ply tire preserves the traditional look and construction style, while radial alternatives are a separate choice that should be evaluated carefully. Anyone considering a change should compare wheel width, tire dimensions, and clearance rather than assuming that a radial equivalent will behave or present exactly like the original-style 640-13.

Radial equivalents for 640-13 include 175R13 as an 80-series metric radial, P175/75R13 as a P-metric 75-series radial, P185/70R13 as a P-metric 70-series radial, and 650R13 as a bias-look radial. These give several ways to stay within a similar fitment family while moving to radial construction.

Each equivalent approaches the original size a little differently, whether through metric sizing, P-metric sizing, or a more traditional bias-look radial presentation. A recommended rim-width range of 4 to 6 inches is associated with these alternatives, and the wheel setup, tire clearance, and intended use should all be reviewed before making the change.

That choice depends on how the 1964 Amphicar is used and how closely the owner wants to stay with a period-style presentation. The primary fitments are bias-ply sizes, 640-13 and 650-13, while radial alternatives exist in equivalent forms such as 175R13, P175/75R13, P185/70R13, and 650R13.

Bias-ply tires make the most sense when traditional construction and vintage appearance are the priority. Radial equivalents can be considered for a different road-use experience, but the decision should include a close look at wheel width, the vehicle’s current setup, and whether maintaining the original-style stance matters more than moving to a different tire construction.

Start with the basics: confirm that 650-13 is the size currently used on the car and that the wheel is a 13-inch rim with suitable width for the tire being considered. From there, the main selection points are bias-ply construction, brand, tire series, whitewall treatment, and the tire’s load specification.

This size offers more variety than 640-13, including Coker Classic and US Royal options with both wide whitewall and narrow whitewall styling. That gives room to balance appearance with fitment details, so the better choice depends on whether the car is being restored for a more traditional look or simply maintained with the right vintage-style proportions.

The available sidewall styles for 1964 Amphicar tires include wide whitewall and narrow whitewall treatments. The 640-13 offering uses a wide whitewall, while the 650-13 size adds both wide whitewall and narrow whitewall options across more than one brand and tire series.

Sidewall choice has a strong effect on how the car sits visually, especially on a compact 1960s collector vehicle like the Amphicar. A wider whitewall tends to emphasize a more traditional presentation, while a narrower whitewall gives a subtler period-style look. Matching that appearance to the car’s restoration direction usually matters as much as the tire brand itself.

Tires for the 1964 Amphicar are available from BFGoodrich, Coker Classic, and US Royal. BFGoodrich appears in 640-13, while the 650-13 size adds Coker Classic and US Royal choices in period-style bias-ply series and different whitewall widths.

Brand choice should be treated as one part of the decision rather than the whole decision. The more useful comparison is how each tire aligns with the size already on the vehicle, the desired sidewall look, the wheel-width range, and the overall restoration direction. That approach keeps the selection focused on fitment and presentation instead of brand name alone.

For a period-style 1964 Amphicar, the starting point is staying with one of the original-type bias-ply sizes used on the car, either 640-13 or 650-13, depending on the wheel and tire setup already in place. Choosing within that size then comes down to whitewall width, brand, and tire series.

A restoration-oriented buyer will usually want the tire’s proportions and sidewall presentation to suit the car’s mid-1960s character. If exact originality matters beyond that, vehicle-specific historical references and marque expertise become important. For many owners, though, the right period-style result comes from matching the correct size family and an appropriate whitewall treatment.

Tire construction changes the visual character of a restored 1964 Amphicar more than many buyers expect. The primary fitments are bias-ply, and that construction supports the vintage look associated with the car’s original era. A modern radial can alter the presentation even when it stays close to the original size family.

That does not make a radial wrong, but it does make the choice more about priorities. Owners chasing a traditional restoration appearance usually stay with bias-ply construction, while those leaning toward regular road use may explore radial equivalents. The key is recognizing that construction affects both the look of the tire and the overall personality of the car.

Yes, modifications can affect tire fitment on a 1964 Amphicar even when the tire size seems correct on paper. Aftermarket wheels, changes in wheel width, altered suspension height, body repairs, or non-original brake components can all influence how a 640-13 or 650-13 tire sits and clears the car.

That is why a modified Amphicar should be measured rather than assumed. Tire-to-fender clearance, steering travel, and the wheel’s actual dimensions all matter, especially when moving from one primary size to the other or when considering a radial equivalent. A careful check before purchase helps avoid rubbing, stance issues, and unnecessary fitment surprises.

Before driving a 1964 Amphicar on new tires, inspect wheel condition, verify the wheel diameter and width, and confirm that the tire size matches the car’s actual setup. It also makes sense to check valve stems, mounting condition, inflation pressure, and whether there is adequate clearance at the fenders and steering components.

A collector vehicle deserves a broader pre-drive inspection as well. Look over the existing suspension, steering, and brake condition so the new tires are not masking another issue. After the first short drive, recheck pressure and look for any signs of rubbing or unusual wear so the tire and vehicle can settle in safely together.

Tires in 640-13 and 650-13 sizes on a collector 1964 Amphicar should be maintained with regular pressure checks, visual inspection, and clean, dry storage conditions. Even when tread wear is low, collector-car tires can age from time, sunlight, ozone exposure, and long periods of sitting rather than from steady mileage.

Routine inspections should look for sidewall cracking, flat-spotting, bulges, cuts, and slow air loss. Moving the car occasionally, keeping it away from prolonged heat and direct sun, and checking the tires before longer drives can help preserve both appearance and safety. Any tire showing age-related deterioration deserves closer evaluation before road use.