1957 Opel Kapitan Tires

The 1957 Opel Kapitan is associated with two tire sizes: 640-13 in bias-ply construction and 175R13 in radial construction. Both use a 13-inch rim, so the size question is really tied to the car's current wheel and tire setup as much as the number printed on the sidewall.

A Kapitan kept in traditional form will often be evaluated around the 640-13 bias-ply size, while a car already running radial-type fitment may point toward 175R13. Checking the exact wheels on the car is important before choosing, especially if the car has been updated, restored, or fitted with replacement wheels at some point in its life.

The tire sizes associated with the 1957 Opel Kapitan both use a 13-inch rim diameter. That is true for the 640-13 bias-ply size and the 175R13 radial size, so wheel diameter remains consistent even though the tire construction and sizing format differ.

Diameter is only part of the fitment picture. Before selecting a tire, it is worth confirming the actual wheel width on the car and making sure the wheels match the construction type being considered. That matters most when moving away from an older bias-ply setup or when the car has replacement steel wheels or aftermarket wheels installed.

The 1957 Opel Kapitan Base uses the same tire-size family covered here, with both 640-13 bias-ply and 175R13 radial associated with the model. There is no separate sub-model-only tire size changing the basic fitment path for the Base.

That makes the selection process more about construction and presentation than trim-level differences. A buyer can focus on whether the car should keep a period-style bias-ply look, move to a radial equivalent path, or stay with a radial setup already on the vehicle, while still confirming the actual wheel dimensions before making a final choice.

For the 1957 Opel Kapitan, 640-13 is a numeric bias-ply tire size. It uses the older sizing system common to mid-century cars, with the code centered on nominal section width and rim diameter rather than the later metric radial format.

That matters because a bias-ply tire affects both the look of the car and the kind of wheel compatibility checks needed if a radial alternative is being considered. Keeping 640-13 supports a more traditional presentation, while changing construction calls for a closer review of wheel width, clearance, and the vehicle's overall setup before making the switch.

Radial equivalents for 640-13 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. Each of those serves as an alternative size path rather than another primary bias-ply fitment.

The practical difference is in sizing convention and overall presentation. The 650R13 keeps a more traditional visual character, while the metric and P-metric options follow more modern radial formats. A 4-6 inch recommended rim-width range is relevant to these equivalents, and the final choice should still be checked against wheel dimensions and available clearance on the car.

Start by confirming the wheel diameter and actual wheel width, then compare the radial option being considered against the car's current tire and wheel setup. On a 1957 Opel Kapitan, that means treating the 640-13 bias-ply size and its radial equivalents as related options that still need a proper fitment check.

Steering clearance, fender clearance, suspension condition, and the car's ride height all matter before changing construction. It also helps to inspect whether the Kapitan already has replacement wheels, since a car modified years ago may no longer match its earlier tire setup. A careful conversion avoids assuming that the right rim diameter alone settles the fitment question.

The first consideration is whether the car should stay with its traditional bias-ply fitment. A 640-13 tire preserves the vintage numeric sizing format and, in available Kapitan product choices, can also bring a strong period-style look through the BFGoodrich Silvertown Classic Bias Ply line and its 2.25 inch whitewall treatment.

Beyond appearance, compare wheel-width compatibility and how the car will actually be used. A lightly driven restoration may call for a different choice than a car seeing regular road miles, even within the same size. It is also worth checking the current wheels and any older restoration work so the tire selected matches the vehicle's present-day setup rather than assumptions about it.

For the applicable products in the 1957 Opel Kapitan fitment range, the visible sidewall style is a wide whitewall on the 640-13 bias-ply offering. That gives the car a distinctly mid-century presentation and makes sidewall appearance an important part of the buying decision, not just a cosmetic afterthought.

A wide whitewall can dramatically change the finished look of a restored or preserved Kapitan, especially on a car where trim, paint, and wheel covers are part of the overall visual theme. Buyers focused on authenticity should still compare the tire's appearance with period photos, marque knowledge, or restoration goals instead of assuming every whitewall treatment is right for every car.

The available product selection for this fitment includes BFGoodrich in the 640-13 bias-ply size. That product appears in the Silvertown Classic Bias Ply series, giving the Kapitan a recognizable vintage-style option in the traditional numeric size associated with the car.

Brand is only one part of the decision. It still makes sense to compare the tire's construction, sidewall style, and rim-width specification with the wheels on the car and the kind of driving planned. On a collector vehicle like the Kapitan, the right brand choice is the one that supports the intended look and fits the actual wheel setup correctly.

A period-style 1957 Opel Kapitan usually points first toward the 640-13 bias-ply size, because it preserves the vintage numeric sizing format and traditional construction associated with the car. In the available product range, that size also carries a strong visual cue through a wide whitewall bias-ply offering.

That does not automatically make every 640-13 tire the right restoration choice for every Kapitan. If exact originality matters, compare the tire's sidewall treatment and overall look with marque references, period photography, or restoration documentation. For many owners, the goal is not strict originality but a convincing era-appropriate appearance that still suits how the car will be driven.

Tire construction changes more than ride feel on a restored 1957 Opel Kapitan; it also changes the visual character of the car. A 640-13 bias-ply tire keeps the older sizing language and traditional stance cues, while a 175R13 or other radial equivalent can give the car a more modern tire presentation.

That visual difference matters on a car from the late 1950s, where wheel openings, trim, and sidewall style all contribute to the finished look. Owners trying to preserve a mid-century impression often start with the bias-ply size, while others may prefer a radial path that softens the vintage look only slightly, especially if a bias-look radial is under consideration.

Yes, modifications can change tire fitment on a 1957 Opel Kapitan even when the tire size itself appears correct. Replacement wheels, changes in wheel width, altered ride height, suspension work, or body repairs can all affect how a 640-13 or 175R13 tire sits in the car's wheel openings.

A modified Kapitan should be checked as it exists today, not only by original specifications. Looking at steering clearance, fender clearance, and wheel dimensions can prevent surprises after installation. That becomes especially important when moving between bias-ply and radial construction, since the construction change may interact with wheel choice and suspension condition in ways a simple size comparison will not reveal.

Before putting a 1957 Opel Kapitan back on the road with new tires, inspect the wheels, lug hardware, valve stems, and overall brake and suspension condition. Tire pressure should be set correctly for the chosen tire, and the car should be checked for obvious rubbing points or alignment issues before regular driving begins.

Collector cars also deserve a close look for old damage or deferred maintenance that may not show up during storage. Side-to-side clearance at the front wheels, smooth steering movement, and even ride height are all worth checking early. A short local test drive followed by a second inspection can catch settling, interference, or air-loss issues before longer trips.

640-13 tires on a collector 1957 Opel Kapitan should be maintained with regular pressure checks, periodic visual inspection, and careful storage habits. Even on a low-mile car, age, heat, sunlight, and long periods of inactivity can affect tire condition as much as road use does.

Look for sidewall cracking, bulges, cuts, flat spotting, uneven tread wear, and any slow loss of air before each driving season and before longer outings. Storage away from prolonged sun, moisture, and ozone-producing equipment helps preserve the tires. On a lightly used Kapitan, maintenance is as much about watching condition over time as it is about counting miles.