1961 Borgward Isabella Tires

The 1961 Borgward Isabella does not use one universal tire size across every sub-model. Base and TS models use either 590-13 in bias-ply form or 165R13 in radial form, while the SW uses either 640-13 in bias-ply form or 175R13 in radial form. All of these fitments use a 13-inch rim diameter.

The first step is confirming whether the car is a Base, SW, or TS, because that determines which size family applies. After that, check whether the car is staying with an original-style bias-ply setup or already uses the radial fitment, and make sure the wheel width still matches the tire being considered.

The 1961 Borgward Isabella uses 13-inch rims across its covered tire sizes. That rim diameter stays consistent whether the car is fitted with 165R13, 590-13, 175R13, or 640-13, so the main fitment differences are in tire size family and construction rather than wheel diameter.

Even with the same 13-inch diameter, wheel width still matters when moving between bias-ply and radial options. A car that has been changed to different wheels over the years should have those wheels measured before ordering tires, especially if the Isabella is an SW using the larger 640-13 or 175R13 size family.

No. The 1961 Borgward Isabella Base and TS share the same tire-size family, using 590-13 as a bias-ply fitment or 165R13 as a radial fitment. The SW uses a larger family instead, with 640-13 in bias-ply form or 175R13 in radial form.

That difference matters because a tire that suits a Base or TS should not automatically be treated as correct for an SW. Owners should verify the sub-model first, then compare the existing wheels and current tire setup, especially if the car has been restored, modified, or converted from one construction type to another.

590-13 is the bias-ply tire size used on the 1961 Borgward Isabella Base and TS. It is a vintage numeric bias-ply format rather than a radial designation, and it represents the traditional construction choice within that smaller Isabella size family.

A buyer looking at 590-13 is usually deciding between keeping a period-style bias-ply appearance or moving to one of the established radial alternatives for that fitment family. That choice should include a wheel-width check, since the available 590-13 bias-ply tire and the radial equivalents do not necessarily share the same wheel requirements.

For 590-13, radial equivalents include 165R13 as an 80-series metric radial, P165/75R13 as a 75-series P-metric radial, and P175/70R13 as a 70-series P-metric radial. For 640-13, the available radial equivalents are 175R13, P175/75R13, P185/70R13, and 650R13 as a bias-look radial.

These sizes are useful alternatives, but they should be treated as comparison points rather than automatic substitutions. Rim-width guidance is 4-5 inches for the 590-13 equivalent group and 4-6 inches for the 640-13 group, and the finished setup should still be checked for wheel compatibility, clearance, and overall suitability to the sub-model.

Start by matching the radial size to the correct Isabella sub-model and original bias-ply size family. Base and TS conversions center on the 590-13 to 165R13 group, while SW conversions center on the 640-13 to 175R13 group, with additional P-metric alternatives and one 650R13 bias-look radial option for the larger bias-ply size.

The practical checks are wheel diameter, actual wheel width, and tire clearance through steering and suspension travel. A car that has older replacement wheels, suspension changes, or body alterations should be inspected carefully, because a radial equivalent may be appropriate in size family but still need verification before it is put into road use.

The most important choice is confirming the correct size family for the sub-model. Base and TS use 590-13 or 165R13, while the SW uses 640-13 or 175R13, so the right decision starts with identifying the car correctly and deciding whether the goal is bias-ply authenticity in appearance or radial construction for a different driving feel.

Once the fitment family is settled, compare construction type, sidewall style, tire series, and wheel-width compatibility. A wide whitewall BFGoodrich bias-ply creates a very different presentation from a blackwall Michelin or Dunlop radial, so the best choice depends on how the Isabella is used and how closely the owner wants to preserve a period-style look.

The available sidewall styles for the 1961 Borgward Isabella are blackwall and wide whitewall. The radial options in 165R13 are blackwall Michelin and Dunlop designs, while the bias-ply choices in 590-13 and 640-13 are BFGoodrich Silvertown Classic Bias Ply tires with wide whitewall sidewalls.

That sidewall difference can shape the entire appearance of the car. Blackwalls usually suit a more understated European presentation, while wide whitewalls create a stronger vintage styling statement, so the sidewall choice should match both the correct tire size and the visual direction of the restoration or driver-level setup.

Michelin, Dunlop, and BFGoodrich all offer applicable tires for the 1961 Borgward Isabella across its covered sizes. Michelin and Dunlop appear in the 165R13 radial fitment, while BFGoodrich covers the 590-13 and 640-13 bias-ply fitments through the Silvertown Classic Bias Ply line.

Brand choice should be considered alongside size, construction, and appearance rather than on brand name alone. A Michelin or Dunlop radial serves a different purpose from a BFGoodrich wide whitewall bias-ply, so owners should compare the tire's role on the car first and use the brand as one part of the final decision.

A period-style 1961 Borgward Isabella usually starts with the correct sub-model size family and the original-style bias-ply construction. That means 590-13 for Base and TS models or 640-13 for the SW, both available as BFGoodrich Silvertown Classic Bias Ply tires with wide whitewall sidewalls.

That approach preserves the vintage sizing format and visual character more closely than a modern radial conversion. Owners pursuing exact historical authenticity should still compare the tire appearance against marque references, photographs, or restoration documentation, since period-style fitment and exact factory delivery details are not always the same thing.

Tire construction changes more than road feel on a restored 1961 Borgward Isabella; it also changes how the car sits visually. The bias-ply choices use vintage numeric sizing with wide whitewalls, while the radial offerings use Euro-metric blackwall sizing that gives the car a more later-service or road-use oriented presentation.

That makes construction part of the restoration decision, not just a driving decision. A buyer who wants a stronger traditional look will usually focus on the bias-ply path, while someone prioritizing a radial setup should think carefully about whether the blackwall appearance still suits the finished style of the car.

Yes. Even though the 1961 Borgward Isabella uses 13-inch tire fitments, aftermarket wheels, altered wheel widths, suspension changes, or body modifications can affect whether the intended tire size works properly on the car. That matters even more because the Isabella already has different size families for Base and TS versus the larger SW.

A modified car should be checked for actual wheel width, steering clearance, and available fender room before moving into either a radial equivalent or an original-style bias-ply tire. Small vintage cars do not leave much room for assumptions, so current hardware on the vehicle matters as much as the nominal tire size.

Before road use, inspect the wheels for correct diameter and width, confirm that the tires match the sub-model, and make sure each tire seats properly and clears the body and suspension. It is also smart to check the spare-wheel area and verify that old wheels have no visible damage, corrosion, or distortion.

Beyond installation, look at basic roadworthiness items such as tire pressure, valve condition, and any signs of rubbing during full steering lock or suspension movement. A short local test drive followed by a second inspection can catch issues early, especially on a collector car that may have spent long periods parked.

Collector-car tire maintenance starts with regular visual inspections, even when the 1961 Borgward Isabella is driven sparingly. Check for sidewall cracking, bulges, cuts, uneven tread wear, and slow air loss, and keep inflation consistent so the tire maintains its intended shape and load support during use.

Storage conditions matter almost as much as mileage on an older vehicle. Keeping the Isabella away from prolonged sunlight, heat, moisture, and ozone sources helps protect both bias-ply and radial tires, and periodic inspection is worthwhile because a lightly used collector car can age its tires out long before it wears them out.