1928 Willys-Knight Tire Fitment Guide

1928 Willys-Knight vehicles use six sizes across three model families. The 56 Series uses 29X5.50 and 550-19, the 66A Series uses 30X5.77 and 30x5, and the 70A Series uses 31X6.00 and 600-19. All six are bias-ply sizes, but they are not shared across the full 1928 Willys-Knight range. Among the sizes with current product listings, both 550-19 and 600-19 mount on 19-inch rims, and 550-19 carries a listed rim-width range of 2.50 to 3.00 inches.

The practical takeaway is that year and make are only the starting point for a 1928 Willys-Knight. You need the actual series identification before you can narrow the tire correctly, because a 56 Series owner and a 70A Series owner may both see a 19-inch wheel application yet still require different tire sizes. If your car has already been restored or altered, compare the sidewall markings on the tire and the wheel diameter on the car before choosing a replacement.

On a 1928 Willys-Knight, 550-19 is a numeric bias-ply tire size. The 5.50 portion refers to nominal section width in inches, written without the decimal in the modern shorthand, and the 19 refers to the wheel diameter in inches. For 1928 Willys-Knight applications, that size belongs to the 56 Series. Available versions include BFGoodrich bias-ply tires in both Blackwall and Wide Whitewall styles.

That matters because a numeric size like 550-19 is easier for many modern buyers to recognize than earlier diameter-by-section markings such as 29X5.50. If your 56 Series uses a 19-inch wheel setup, 550-19 is the size with current listed choices and gives you an appearance decision between blackwall and wide whitewall. It should still be confirmed against the wheel and the car’s existing markings rather than assumed from year alone.

On a 1928 Willys-Knight, 29X5.50 is an antique diameter-by-section size. The first number gives the tire’s overall diameter in inches, while the second gives nominal section width in inches. That is different from a later numeric bias-ply size such as 550-19, where the final number identifies wheel diameter. Within the 1928 Willys-Knight range, 29X5.50 is tied specifically to the 56 Series.

Understanding that format helps avoid mixing unlike sizing systems when working on an early car. An owner who sees 29X5.50 on the vehicle should treat it as a series-specific early fitment, not as a direct synonym for every other 1928 Willys-Knight tire option. Antique markings like this usually matter most when the goal is to keep the car visually and mechanically close to period practice, so it is worth checking the actual tire and wheel before moving to replacement planning.

No, 1928 Willys-Knight models do not all use the same tire size. The 56 Series uses 29X5.50 and 550-19, the 66A Series uses 30X5.77 and 30x5, and the 70A Series uses 31X6.00 and 600-19. Each pair is specific to its own series, which reflects how late-1920s manufacturers matched tire dimensions to chassis scale and intended load. Even where two sizes may look similar at a glance, they should not be treated as universal across the full Willys-Knight lineup.

That series-by-series split means model identification is the first fitment step. A buyer who only knows the car is a 1928 Willys-Knight can still end up in the wrong size family without confirming the actual series plate, body identification, or the markings on the existing tires and wheels. Once the model is pinned down, the rest of the decision becomes much simpler because all listed choices for this year and make remain within the bias-ply, period-style category.

1928 Willys-Knight tire offerings include both Blackwall and Wide Whitewall styles, although the available styles depend on size. In 550-19 for the 56 Series, BFGoodrich offers both a Blackwall and a 3.25-inch Wide Whitewall. In 600-19 for the 70A Series, the available listed option is a Lester Wide Whitewall. Those sidewall differences change the look of the car even when the underlying construction remains bias-ply.

For a late-1920s American luxury-oriented car such as a Willys-Knight, wide whitewalls are often the visual choice owners gravitate toward for formal restoration presentation, while blackwalls can suit a more restrained or utility-oriented appearance. The key is matching the sidewall style to the character you want the finished car to project, after you have already confirmed the correct series and size. Sidewall style should follow fitment, not replace it.

Two brands appear in current 1928 Willys-Knight tire offerings: BFGoodrich and Lester. BFGoodrich appears in 550-19 for the 56 Series, with both Blackwall and Wide Whitewall bias-ply choices. Lester appears in 600-19 for the 70A Series as a Wide Whitewall bias-ply option. The listed products stay within the period-appropriate bias-ply construction that a 1928 Willys-Knight owner would expect for an era-correct presentation.

Brand choice on an early collector car usually comes after the more important decisions of identifying the correct model and confirming the correct size family. Once you are in the right size, the brand can influence the final look through sidewall treatment and the overall restoration character of the tire. Because each listed brand here appears in a specific size rather than across the whole 1928 Willys-Knight range, brand availability follows model fitment instead of the other way around.

For a 1928 Willys-Knight 56 Series, both BFGoodrich 550-19 tires share the same basic fitment: bias-ply construction, a 19-inch rim diameter, a listed rim-width range of 2.50 to 3.00 inches, and a listed load capacity of 1040 pounds at 32 psi. The visible difference is sidewall treatment, with one tire in Blackwall and the other in a 3.25-inch Wide Whitewall. The listed weights also differ slightly, at 21 pounds for the Blackwall and 23 pounds for the Wide Whitewall.

That means the choice is mostly about presentation rather than changing to a different size or wheel fitment. A blackwall gives a simpler, more understated look, while the 3.25-inch whitewall creates a more formal late-1920s appearance that many restorers prefer on upscale cars. Since both remain in the same size and construction family, the visual effect on the finished car is the main deciding factor once fitment has been confirmed.

Rim-width guidance is listed for 1928 Willys-Knight in 550-19, where the BFGoodrich bias-ply tires call for a 2.50- to 3.00-inch rim width on a 19-inch wheel. The 600-19 listing confirms a 19-inch rim diameter, although no rim-width range is shown alongside that product here. The remaining Willys-Knight sizes in antique notation are model-specific bias-ply fitments, but no additional rim-width figures accompany them in the available listings.

For an owner, that means the safest approach is to confirm the wheel actually on the car before choosing a replacement tire, especially on a vehicle that may have changed hands or been restored over many decades. On a 56 Series running 550-19, the published 2.50- to 3.00-inch range gives a clear benchmark. On the other sizes, measuring the wheel and comparing it against the chosen tire’s published specifications is the right next step.

Original 1928 Willys-Knight wheels should only be used with the tire sizes intended for the specific series. The 56 Series, 66A Series, and 70A Series each have their own size pair, and only two of those sizes with current product listings, 550-19 and 600-19, clearly share a 19-inch rim diameter. That does not make all 1928 Willys-Knight wheels interchangeable across the lineup, especially because the other sizes are expressed in earlier diameter-by-section form and belong to different model families.

The practical point is to think in terms of your exact car, not the whole make. A 19-inch wheel on one Willys-Knight series does not automatically mean another series used the same wheel width, tire profile, or intended load range. If the car still carries original-style wheels, verify the wheel diameter and compare it with the tire size called for on that series before assuming a swap is acceptable.

A stored 1928 Willys-Knight should be kept away from direct sunlight, electric motors, battery chargers, furnaces, and other ozone-producing equipment that can age sidewalls over time. The storage area should stay clean and dry, and the car should not sit for long periods on underinflated tires. Because 1928 Willys-Knight tires are bias-ply in these fitments, they are more prone to temporary flat-spotting after prolonged static storage than a later radial collector tire would be.

Owners who store a Willys-Knight for months at a time usually benefit from rolling the car periodically or taking weight off the tires with stands placed correctly under the chassis, depending on the restoration and storage setup. The goal is to reduce concentrated stress in one contact patch while protecting the tire from heat, ozone, and moisture. A little storage discipline goes a long way on prewar-style tire construction.

On a 1928 Willys-Knight, tire age usually matters more than tread mileage because collector cars are often driven sparingly. A sensible rule is to begin evaluating tires closely once they are about five to seven years old and to treat roughly ten years as the point where replacement deserves serious consideration, even if the tread still looks usable. The DOT date code on the tire helps establish age, and sidewall cracking, hardening, or repeated pressure loss can justify replacement sooner.

That age-based approach is especially important on a car that may spend long periods parked between outings. A Willys-Knight used only for shows, tours, or occasional fair-weather driving can still age its tires significantly while barely wearing the tread. If the car has older tires of uncertain age, establishing a date baseline before the next driving season is one of the most useful maintenance steps you can take.

Tires on a 1928 Willys-Knight should be inspected before every drive, with a more thorough inspection before any extended tour or event. Look for sidewall cracking, cuts, bulges, embedded debris, uneven wear, and any sign that the tire is losing pressure between outings. Because these are period-style bias-ply fitments, the inspection should also include a visual check of the tread profile after the car has been sitting to make sure any temporary flat-spotting works out normally as the tire rolls.

A short pre-drive walkaround can prevent problems that are easy to miss on a low-use collector car. If the car carries a side-mounted or rear-mounted spare, inspect that tire too rather than assuming it is ready for service. On a vehicle of this age, tire condition is only one part of readiness, but it is one of the few checks you can do quickly before every trip and still gain real safety margin.

A 1928 Willys-Knight 56 Series would have been fitted in the bias-ply era, and the size family associated with that model is 29X5.50 and 550-19. Those sizes match the period practice of using bias-ply construction and early sizing systems during the late 1920s. No original-equipment brand should be assumed from that alone, because original fitment could vary by market, dealer practice, or period supply conditions even within the same make and year.

For restoration work, the important point is getting the size family and construction type right before worrying about smaller appearance details. If your goal is strict authenticity, compare your car’s surviving evidence with factory literature, period photography, and Willys-Knight marque resources. That is especially helpful on prewar cars, where body style, export delivery, and restoration history can all influence what is considered correct for a specific example.

Correct tire fitment does matter when showing a 1928 Willys-Knight, especially in events that judge authenticity rather than only presentation. Judges and knowledgeable enthusiasts typically notice whether the tire size belongs to the right series, whether the construction is era-appropriate bias-ply, and whether the sidewall style suits the period character of the car. A visibly incorrect size family or a style that clashes with the restoration can distract from an otherwise careful car.

That does not mean every event uses the same standard, but it does mean tire choice is part of the overall restoration story. On a late-1920s car, the tires frame the stance and visual proportion of the body in a way modern enthusiasts immediately notice. If the car is being prepared for judged competition, consult the event rules and marque specialists early so the tire choice supports the class expectations instead of working against them.

On a 1928 Willys-Knight, antique-format sizes such as 29X5.50, 30X5.77, 30x5, and 31X6.00 express overall tire diameter and section width, while numeric sizes such as 550-19 and 600-19 express nominal section width and wheel diameter. Both belong to the bias-ply world of the late 1920s, but they represent two different naming conventions a restorer may encounter when comparing period references and replacement options. They are not interchangeable labels simply because they appear on cars from the same year.

That distinction matters during restoration because the sizing language often shapes how a car sits and how accurately it reflects period practice. A buyer researching a Willys-Knight should treat each notation as part of the car’s original fitment identity, not just as a cosmetic variation in how the tire is described. If the car carries surviving wheel or tire markings, use those as a guide and then confirm against marque knowledge before finalizing the replacement.

1928 Willys-Knight tires can be appropriate for highway use when they are the correct size, in sound condition, and used within the operating limits of their construction, but the listed products here do not include published speed ratings. Because every 1928 Willys-Knight size in this group is bias-ply, the driving feel and tracking behavior will remain different from a modern radial-equipped vehicle. On a car of this age, the vehicle’s brakes, steering condition, suspension wear, and overall mechanical state are often at least as important to road safety as the tire itself.

That means highway use should be approached with the whole car in mind rather than focusing on the tire alone. A properly sorted Willys-Knight driven at sensible speeds can be enjoyable on secondary roads and moderate highway stretches, but long-distance or higher-speed touring demands extra attention to chassis condition and tire age. If the car has sat for years, a thorough inspection before regular road use is more important than any single feature on the sidewall.

Inflation pressure on a 1928 Willys-Knight should follow the tire manufacturer’s published limits for the exact size and the vehicle maker’s original recommendation where available. Among the listed tires here, 550-19 carries a stated load figure of 1040 pounds at 32 psi, and that number applies to that size and product family rather than to every 1928 Willys-Knight tire. No pressure figure should be transferred from 550-19 to the antique-format sizes or to 600-19 simply because they belong to the same make and year.

The best practical approach is to start by identifying the exact tire size on the car, then compare the tire maker’s rating with the factory guidance for the specific series. Pressure tuning on a collector car can affect ride, steering effort, and tread wear noticeably, so using the wrong figure from another size can create avoidable problems. Keep a pressure log if the car is driven infrequently, since slow pressure loss is common on long-stored classics.

Before a longer drive in a 1928 Willys-Knight, inspect each tire for cracking, cuts, bulges, uneven wear, and correct inflation, and check that the spare is usable as well. On the listed 550-19 products, confirm that the tire still sits correctly on its 19-inch wheel and that the wheel condition remains sound. Because a Willys-Knight is a late-1920s automobile, the tire check should happen alongside a broader review of brakes, steering play, wheel bearings, fluid levels, and lighting before any extended outing.

That broader pre-drive habit matters more on an older touring car than on a modern daily driver. Tires can look presentable at a glance yet still be too old, too dry, or too low on pressure for confidence over a full day’s driving. Taking ten extra minutes in the garage often reveals problems while they are still small, which is far better than discovering them on the shoulder miles from home.